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Grading the 2015 version of Pew study of public attitudes toward science

So everybody knows that the Pew Research Center released a cool study yesterday on public attitudes toward science & on differences between public & scientists (or at least AAAS members; it’s worth noting that AAAS membership isn't limited to scientists per se).

It was a follow up to Pew’s classic 2009 study of the same -- & it makes just as huge and valuable a contribution to scholarly understanding as that one, in my view.

Lots of people have said lots of things already & will say even more. But here are a few thoughts:

1. Pew does great work in measuring US public attitudes toward science & scientists.  They ask questions that it is sensible to believe measure general public regard for the enterprise of science, and keep track over time.

When one adds their findings to those collected by the National Science Foundation and the National Opinion Research Center at the University of Chicago, which conducts General Social Survey, source of most of the NSF's annual "Science Indicator" measures, one can really form a good view of how the US public feels about science.  

People should ignore all the bogus studies that administer strange questions to M turk workers -- there are tons of those & they always report really weird, sensational findings.  

Who needs data? It's obvious!2.  This report, like the 2009 one, shows that Americans basically love science.  By overwhelming margins, they report admiration for scientists and positive appraisals of what scientists do.  This is consistent with what the NSF Science Indicators, which are released every year, show too.

3.  Still, there is almost this weird reluctance in the Center's press release and commentary to accept or clearly articulate this conclusion!

It's common wisdom that public disputes over science stem from a “creeping anti-science” sensibility in American society.

Scholars who actually study public attitudes toward science, however, know that that view is unsupported by any convincing, valid data.  Indeed, the Pew and NSF Indicator reports show that there is overwhelming trust-- across all demographic, political, and other types of cultural groups (religious & nonreligious, e.g.).  

The 2009 Report helped to try to correct the “common wisdom” in this regard.

But the 2015 Report seems committed to avoiding any confrontation with this view. Instead, by employing a strategy of silence, inapt juxtaposition, and emphasis of irrelevant data, the Center commentary seems committed to consoling those who hold this fundamentally mistaken understanding of the sources of public conflict over science.

mmmmmmm... science ....It's almost as if Pew feels disappointed to pop the balloon of self-reinforcing popular misunderstanding on this issue with the needle of its own data.

4. Consider the "gap" between scientists & public on evolution.  

Yes, it's there.

But it is well established that public opinion responses to the question “do you believe in human evolution” have zero connection to what people know about either evolutionary science or science in general. 

It's also perfectly clear that this "gap" in public and scientific understandings has nothing to do with public respect for scientists.  

The 2009 Pew Report made that clear, actually, reporting data showing that those who said they "disbelieved in" evolution as well as those who said they "did" both had highly positive views of science's contribution to society.

The Report and Alan Leshner’s commentary for the 2009 Report both emphasized that there was no meaningful differences in that regard between people who said science sometimes conflicts w/ their religious views & those who said it doesn't.

Nothing at all has changed--nothing. But is there anything comparable in this yr's report? Nope!

Leshner himself did write a very thoughtful commentary in Science. 

He's still championing respect for and respectful dialogue with diverse memers of the public: good for him; he's a real science-of-science-communication honey badger!

But even he seemed to think that getting his message across required indulging the "creeping anti-science" meme, warning that "the public's perceptions of scientific expertise and trustworthiness" risk being "compromised whenever information confronts people's personal, personal, or religious views"-- conclusions that actually seem completely contrary to the data presented in both 2009 and 2015.

5. Same w/ the “gap” on climate change.  

It's clear that climate change opinions don't measure either science comprehension, knowledge of climate science in particular, or respect for or attitudes toward science.  

In 2009, Pew wanted people to see, too, that public conflict over climate change did not originate in any disagreement about the value of science or trustworthiness of scientists. It emphasized that both climate-change "believing" & "disblieving" members of the public had the same positive views in this regard.

Not so in the 2015 report, where the "gap" on climate change is repeatedly used to qualify the finding that the public has high regard for science. (Interesting that only 87% of AAAS members indicated they "believe in" AGW; I'm sure they understand the evidence for AGW and even use the evidence "at work.")

What makes this all the more strange is that the 2015 Report recognizes that the public's disagreement over AGW mirrors a public disagreement over what scientific consensus is on this issue (a phenomenon that can be attributed to ideologically biased assessments of evidence on both issues).  

In other words accepters and nonacepters alike believe "science is on their side" -- much the way that nations at war believe that God is....

For sure, the debate is alarming and contrary to enlightened democratic decisionmaking.  

But if anyone thinks the source of the debate is lack of science comprehension on the part of the public or lack of public confidence and trust in science, they are themselves ignoring all the best evidence we have on these issues!

Pew's job is to help remedy this widespread form of science-of-science-communication illiteracy.

6. The data reported on public attitudes on GM foods is super disappointing.  

Social scientists know that surveying the public on issues that it has never heard of generates absolutely meaningless results.

GM food risks are in that category. 


American consumers’ knowledge and awareness of GM foods are low. More than half (54%) say they know very little or nothing at all about genetically modified foods, and one in four (25%) say they have never heard of them.

Before introducing the idea of GM foods, the survey participants were asked simply ”What information would you like to see on food labels that is not already on there?” In response, most said that no additional information was needed on food labels. Only 7% of respondents raised GM food labeling on their own. . . .

Only about a quarter (26%) of Americans realize that current regulations do not require GM products to be labeled.

Hallman, W., Cuite, C. & Morin, X. Public Perceptions of Labeling Genetically Modified Foods. Rutgers School of Environ. Sci. Working Paper 2013-2001. 

Americans don't fear GM foods; they eat them.

No meaningful inferences whatsoever can be drawn from the "gap" in attitudes between members of public & scientists on this issue.  

Very un-Pew-like to play to common misunderstandings about this by treating the “gap” between public and scientists on GM as supporting any meaningful inferences about anything.

6.  Also very out of character is Pew's calling attention to minute changes in the overwhelming levels of support for science reflected in particular items:

I'm sure they were just trying to throw a bone to all those who "just know" -- b/c it's so obvious-- that we are living in the "age of denial." But if the latter seize on these changes as meaningful, they'll only be making fools of themselves. 

For perspective, here are comparable data, collected over time, from NSF Indicators (click on them for larger displays).  

That anyone can see in these sort of data evidence for a "creeping anti-science" sensibility in the general US population or any segment of it is astonishing -- something that itself merits investigation by public opinion researchers, like the excellent ones who work for Pew!

But the bottom line is, the job of those researchers isn't to feed these sorts of persistent public misimpressions; it's to correct them!

* * *

How would I grade the Pew Study, then?

“A” for scholarly content.”

“C -” for contribution to informed public understanding.

Overall: “B.”


Science of Science Communication 2.0, Session 3.1: Science comprehension: who knows what about what—and how?

Okay, this is "session 3" post for virtual "Science of Science Communication 2.0."  The real space version got snowed out!  

But the discussion I was hoping for (based on these readings) was mainly one on how group affinities contribute to transmission of scientific knowledge.  

"Cultural cognition" is normally associated with idea that such affinities distort such transmission.  

But my hunch is that cultural cognition is in fact integral to citizens' reliable apprehension of what is known to science; that the sorts of pathologies that we see in which people with different cultural identities use their reason to form and persist in opposing views on risks and related facts is a consequence of a polluted science communication environment that disables the normally reliable reasoning strategies people use (including observation of what others who know what's what about what are doing and saying) to figure out what is known...

But I admit to being uncertain about this!  Indeed, I readily admit to being uncertain about everything, including the things I am most confident that I think I understand; certainly I am committed (I hope able) to revise anything I blelieve on the basis of any valid evidence I encounter.

But here I am not even as confident as I'd like to be about the state of the evidence on my conjecture -- that cultural cognition is not a bias, but is integral to the normal process by which diverse people usually converge on the best evidence.  And so I was & remain eager for reflections by others!

Below are the questions I posed to motivate student reading & orient discussion for this session.  Next session, in which we'll be doing "double time" to make up for lost class, will feature trust in/of science...

  1. What is the relationship between the sort of critical reasoning proficiency featured by Baron’s “actively open-minded thinking” and Dewey’s understanding of “scientific thinking”?

  3. Is critical reasoning proficiency essential for science comprehension on the part of a non-scientist, either in her capacity as personal decisionmaker, member of civil society, or democratic citizen?

  5. Are conflicts over policy-relevant science plausibly attributable to deficits in critical reasoning proficiency?

  7. Does the effective use of scientific knowledge by non-scientists—in the various capacities in which their decisions should (by their own lights) be informed by it—depend on their being able to comprehend what it is that science knows?

  9. Is it possible for citizens to reliably recognize who knows what is known by science without being able to comprehend what it is those individuals know?  If so, how? Does their ability to do that depend on their possessing the sort of reasoning proficiency emphasized by either Baron or Dewey? If not, what does it depend on?

  11. How does Popper’s understanding of the transmission of scientific knowledge relate to Miller’s, Dewey’s, and Baron’s?

  13. Do group affinities—ones founded on common outlooks and values—promote transmission of scientific knowledge or inhibit it?  In either case, how?

There is pervasive cultural consensus on the value of childhood vaccines in the U.S.; so why do people *think* that being anti-vaccine reflects any particular cultural predisposition?

A reporter who was covering the current measles outbreak asked me a question about the connection between vaccine hesitancy—the reluctance of parents to get their kids vaccinated—and the contribution cultural or political predispositions make to vaccine risk perceptions. 

In the background of the question were a couple of facts that this reporter gets but that a lot other reporters and people generally don’t: first, that parents in the US along with rest of the general public in this country are overwhelmingly pro-vaccine; and second, that the people who belong to the small segment of the population that is anti-vaccine are big time outliers in all the social groups—cultural, political, religious and so forth—that make up our basic inventory of “who” people are.

Someone didn't get the memo ... click to see whoOn the first point, briefly: Despite the media din to the contrary, the US has enjoyed impressively high childhood  vaccine rates—over 90%, the public health target, for all the recommended universal vaccinations, including MMR—for going on 15 yrs.  The percentage of parents not getting their kids vaccinated has remained below 1% that entire time.

Fortunately, the Wakefield affair, which did have a significant impact on vaccine behavior in the UK (maybe other countries, too, but the truth is, many European countries have lower vaccine rates than they should have had for a long time), didn’t have a comparable effect in the US.

Vac rate trends? Ask the CDC...On the second: As documented in various places including the CCP  Vaccine Risk Perceptions and Ad Hoc Risk Communication study, there is no meaningful correlation between vaccine risk perceptions and the sorts of characteristics that usually indicate membership in one or another cultural group.  

The correlation between such risk perceptions and political outlooks, e.g., is close to nil.

What's the correlation between vaccine risk perceptions and political outlooks? Click & see for self

Likewise, contrary to the empirically uninformed, illiberal, counterproductive "anti-science trope," the cultural groups whose members are divided on climate change and evolution are in fact in overwhelming agreement that vaccine benefits outweigh their risks. 

Still, the reporter wanted to know, given all this, how come it appears to him and others that there is a correlation between anti-vaccine, or concerned about vaccine risks, and a cultural style that is, I guess, left-leaning in politics, anti-industry or –capitalist, highly “naturalist” etc.

What's the relationship between non-acceptance of global warming or human evolution and belief that vaccines are unsafe? Click for answerVery reasonable question.

What’s more, I don’t have an answer that I’m particularly confident in! 

I do have some conjectures, and so I thought I’d share them here & ask others what they thought.

Also, at about the time I was writing this email, Chris Mooney was addressing this same question in thoughtful essay that I encourage others to read—I think my views are pretty close to his!

My thoughts on this question:

I'm really not sure what to say, but my hunch is that there is a huge sampling bias risk here when we try to draw on own experience to figure out vaccine risk perceptions.  

It's clearly the case -- just no arguing w/ it, really! -- that the vast majority of people in US, including parents, are not hostile to but in fact very favorable disposed to childhood vaccinations.  This is true across all the sorts of cultural groups that normally come to mind when we think of risk issues like climate change etc. where there really are very deep & strong cultural divisions.

Yet some people are clearly anti-vaccine. If we see them, what are we to make of them?  

It's hardly a surprise that they will have integrated their views into their cultural understandings generally.  That is, there will be coherence, for them, in their positions on vaccines and their ones on various other issues.  

So if they happen, say, to be the kind of person who has an egalitarian, collectivist style & is anxious about environmental issues & suspicious of corporations and the like, then their positions on vaccines will likely be of a piece with that.

But then if we were to say to ourselves, -- "a ha! Being anti-vaccine coheres with being that sort of person!," we'd be making a mistake.  At a minimum, we'd be making a mistake b/c we'd be neglecting to consider all the people who share that person's cultural style -- and indeed hold the standard collection of risk perceptions that go along with it -- but who don't have anxieties about vaccines!  Those people would outnumber the anti-vaccine mom or moms we are talking about -- by orders of magnitude.

We'd also be at risk of making another mistake.  

That particular anti-vaccine group of moms you ran into -- they might not even be representative of all the other anti-vaccine folks.  Indeed, if you met them at whole foods (I have no idea if this applies to you, but you'll get the idea), then likely your sense of what the anti-vaccine people are like is undercounting all the anti-vaccine people who don't shop there.  They don't shop there b/c doing so would be contrary to their cultural style.  They might be very conservative -- maybe they are religious fundamentalists of one sort or another.  Those might be people you never happen to run into!  As a result, the people who are like that who are anti-vaccine will be missing from your mental census.

Of course, so will all the people "like that" who are not anti-vaccine.  They will, just as in the case of the moms at whole foods, outnumber the anti-vaccine members of their groups by orders of magnitude.  But possibly b/c they are more likely to encounter anti-vaccine types in the community in which they interact w/ people most of the time, they might also have a misimpression that anti-vaccine people actually are more likely to hold values like theirs!

Now one more really really important thing:  I actually am pretty convinced that most of the parents whose kids miss vaccinations are not part of any movement.  

The "movement" is there, but it is small & gets way more attention than it deserves precisely b/c it is loud, in people's faces, and really good at provoking hysterical denunciations of them.  

But more importantly, there's every reason to believe that most of the parents whose kids are not getting vaccinated don't belong to any movement at all.  These are parents who are just nervous, not agitated.

They aren't loud and obnoxious.

They aren't demonstrating or getting in anyone's face.  

 They are not wearing buttons saying "vaccines give kids autism! McCarthy for President   in '68 '16!"

And for that reason it's actually hard to find them--which is very unfortunate b/c almost certainly they could be reassured by a good public health professional trained to give them sensible, evidence-informed risk counseling.

The best work being done on vaccine hesitancy is the research to develop a screening instrument for new parents to identify which ones are likely to end up w/ kids who miss vaccination.  With that sort of instrument in hand, ongoing empirical research to develop an effective risk counseling protocol targeted at these very parents could be carried out much more effectively too.

Rather than propagating the misimpression that a “growing crisis of public confidence” among “a large and growing number” of “otherwise mainstream parents” has generated an “erosion in immunization rates”  in the U.S. (these are in fact demonstrably false claims), those who truly want to make universal vaccination in this country even more effective should be calling for more resources for the scientists doing this excellent and vital research.

It's fine to criticize the small cadre of attention seekers who are spreading misinformation about vaccines. They are a bunch of idiots & a menace etc.  

But engaging in relentless, self-important, attention-grabbing displays of denunciation in return is itself dangerous for the vaccine science communication envirionment, and distracts us from what's really needed: the development of valid, reliable methods that practioners can use to identify the much larger group of parents who are merely anxious and supply them with tailored risk counseling that would give them the same sense of relief & happiness that everyone else gets from knowing that their kids won't get the horrible disease that were our grandparents’, great grandparents’, great-great grandparents’ et al’s biggest nightmare.


Weekend update: Are GM foods toxic for the science communication environment? Vice versa? (video lecture & slides)

The National Academy of Sciences Public Interfaces of the Life Sciences program has posted videos from its recent Public Engagement with Gentically Modified Organisms symposium.  It was a really great event with lots of interesting presentation and even more fascinating discussion and debate among the participants.

I gave a presentation on the first day: "Are GM foods toxic for the science communication environment? Vice versa?" (slides here).  Also was on a panel the last day with science communication genius Rick Borchelt,  director of the Office for Communications and Public Affairs Department of Energy; and with Helene Dillard, from UC Davis, and Molly Jahn, from the University of Wisconsin-Madison, both of whom offered harrowing insights into the contentious atmosphere surrounding academic research on GMOs and the difficulties that poses for scientists who want to participate in public deliberations on the subject.

Strongly recommend you watch all the videos if you didn't get a chance to attend or watch live (or even if you did and the alternative is to, say, grade fall semester exams!)

Event highlight: Scheufele demonstrates "performative risk communication" by eating bowl of Frankenberry (he did get sick, but only b/c the cereal had been sitting around since 1973)


Should we care about the public's *climate science* literacy? What is "ordinary climate science intelligence" *for*?

A friend of mine posed this very appropriate, very basic,  very important question/challenge to me after reading the Measurement Problem:

One thing i was left wondering after reading the paper was "should we care about people's OCSI ["Ordinary Climate Science Intelligence"] scores"? does "climate science comprehension" matter for anything meaningful? should we invest (any) resources in trying to increase people's science comprehension in this arena? and if so, WHY? does it, for example, correlate with people's ability to meaningfully/productively engage in the sorts of collective decision-making and planning processes happening in southeast florida? or do you simply see it as a valid end, not a means to anything on the "confronting climate change" front? i'm not sure what your take is on this, exactly, as it seems at some points that you do advocate communicators learn how to do exactly this (improve comprehension), perhaps by looking to science teachers who have figured out effective strategies in other contexts (evolution); but at other points (i think) you say that climate sci comprehension has nothing/little to do with the cultural polarization that seems to inhibit any large-scale collective response to the issue (which, as you say, should come as little surprise). or perhaps both of these statements are true to your thinking, but then it's less clear why (for what purpose) you advocate the former (coming back to the question of, "what is climate science comprehension FOR in a culturally polarized world?"). 

My answer:

OSCI items & responsive curves-- click it! On Ordinary Climate Science Intelligence (OCSI) assessment scores: I think the scores are useful for exploring questions and testing hypotheses about why there is public conflict over climate change.

E.g., is the source of public conflict on this issue attributable to differences in comprehension of either the rudimentary mechanisms of this climage change? 

Or perhaps to their “unfamiliarity” with the evidence that climate scientists have compiled on the causes and consequences of it?

OCSI can help to answer those questions: because it shows that members of groups polarized over the existence of climate change and the contribution humans are making to it have comparable understandings (and misunderstandings) about those matters, it gives us less reason to credit those explanations than we’d have otherwise.

Indeed, OCSI helps us to see, too, that survey items that assess public “acceptance” of human-caused climate change simply aren’t measuring anything having to do with knowledge of climate science at all.  They have no correlation whatsoever to scores on a rudimentary climate literacy test and instead cohere with—behave exactly like other observable indicators of—their cultural identities.

As I explain in The Measurement Problem, OCSI was meant essentially to be a model of an assessment test, one designed to examine whether it is possible, with appropriately worded items, to disentangle (unconfound) cultural identity & knowledge when measuring how much people know about climate change.

But if we want to measure people's understandings of climate science, then I am sure it would be possible to do better than OCSI!

Your question, I take it, is actually more basic: given what we can see from OCSI, why should even want to measure how much people understand about climate science? Why should we care?

There's no answer, of course, that doesn’t presuppose some sort of normative goal.

The goal of most people who collecte data on the issues we are interested in is simply to "move the needle" of public opinion on "belief in" human-caused climate change.  For them, I guess the results of the paper suggest that they should "not care" whether anyone comprehends anything meaningful about climate change. Because what they “believe” about human-caused climate change turns out not to have anything to do with what they know.

Indeed, the paper shows that, if the goal is simply the instrumental one of generating public engagement with the issue of climate change, advocates should stop obssessively measuring and minutely analyzing the percentage of the public who say they believe in (accept) human-caused climate change

Again, what people say about that is measures only of their cultural identities—who they are.  Their response to “do you believe in human-caused climate change” questions not only don’t measure what they know.  They don’t even measure whether they are worried and concerned about climate change!

The consistently wrong answers most believes & skeptics give about the extent and nature of the dangers posed by climate change (e.g., that it will cause increases in skin cancer, or prevent plant photosynthesis) strongly suggest that believers and skeptics alike (in the general public at least) are very alarmed, as an emotional or affective matter, about the risks human-caused climate change poses.

What those who are trying to mobilize public opinion in this way should be trying to figure out is why their style of advocacy doesn’t tap into this reservoir of concern but instead reliably, predictably, inevitably triggers the identity-protective response that is reflected in the “No, I don’t, you asshole!” answer that 1/2 the US public gives when asked (over & over & over in polls that aren't advancing anyone's understanding of anything at this point) “do you believe in human-caused climate change?” 

But there are bunch of other goals one could have—I’d say, should have—besides the navel-gazing one of “needle moving.” All of them support developing an even better instrument for assessing what ordinary  people know about the science of climate change.

One is to help ordinary members of the public recognize information important to the decisions that they will make as citizens in self-governing communities the welfare of which will be affected by actions they take in relation to a changing climate.

Another would be to create communication materials that make it possible for the relatively small portion of the population who is genuinely curious about what we know about a changing climate to satisfy that interest.

Another would be to educate young people who might, if they are taught well and made excited by what they learn, become either climate scientists or adults who are genuinely curious about what we know and who, in any event, will become people who need to make decisions informed by the best evidence in their own private lives (as, say, property owners or business people; or farmers) or as citizens whose communities will be affected by climate change.

For all of those goals and related ones, then there will be value in having not an "OCSI" but a variety of them suited for the goal at hand.  

As I said in the paper, e.g., I think it is silly to measure whether citizens  know that the North Pole ice cap melting won't cause flooding; it's enough for them to know that melting ice sheets are creating a risk for people as a result of climate change.

They know that!

But if one's goal is to educate young people, "North Pole" might be a pretty good item -- which is to say, it might actually be contributing to measurement of the latent comprehension capacity that educators should be trying to instill.  So there are values in having OCSIs for these purposes that are actually tied to the sort of knowledge and comprehension capacities that it makes sense for those transmitting scientific information to focus on in the context in which they are operating.

The reason it would be nice to have on OCSI for the "curious consumer of science," too, is so that those who are part of the (truly amazing!) profession that is committed to serving him or her can figure out whether their efforts are working as well as they want.  

For all of these actors, there will be domain-specific “OCSIs” better than the experimental one featured in The Measurement Problem.  But I hope that the experimental OCSI can help those developing these practical, real-world OCSIs to see that they can and must “disentangle” identity and knowledge in constructing them. 

Well, those are my thoughts.  What do you think?


Science of Science Communication 2.0, Session 2.1: What is science literacy? And what is it for?

So yesterday was session 2 of the "real space" version of Science Science Communication course ver 2.0.  The topic was public "science literacy" or "comprehension" & whether the NSF Indicators and other standardized assessments are "measuring what counts."  The list of assigned readings are here.

Rather than summarize or sound off (again; I've done 738 posts on this topic since topic since this blog started in 1973), I thought I'd just post some questions & let you-- the 14 billion students who enrolled students in the "virtual" version of course (most of whom registered via Tamar Wilner's site) -- say what you think (& of course, ask and answer different questions if you like).

  1. How important is general scientific knowledge for a general member of the public? Does he or she have to understand particular bodies of science or be able to comprehend scientific evidence to be able reliably to identify and use of scientific knowledge in his or her personal life? In his or her role as a democratic citizen?

  2. Is the NSF science indicators battery a valid assessment of science literacy? What is the battery measuring exactly? And how reliably?

  3. What does Miller’s “civic science literacy” (CSL) measure? Are the elements of knowledge or the dispositions it measures essential for individuals to be able to recognize and use valid scientific knowledge in their lives?  What sort of evidence is there on that question?

  4. Is administering a public “science literacy” test to scientists a useful way to validate such a test?

  5. How does Miller’s CSL  relate to Dewey’s position that “scientific method” just “is thinking”? What might a measure of scientific literacy—or however one might characterize it—look like?  




What does & doesn't count as valid evidence of "ideologically motivated reasoning" & "symmetry" of the same

A friend wrote to me posing a question, implicit in which are a bunch of issues about what counts as valid evidence of motivated reasoning & the symmetry of it across the left-right "spectrum" -- or cultural worldview spectra.  

I've addressed many of these issues, most more than once, in various posts.

 Indeed, I have on many occasions noted that almost everything I say is something I've said before, including that I've already noted on many occasions that everything I have to say is something I seem already to have said before. I think this is just sort of normal actually, when one is engaged in a sort "rolling conversation" w/ a fuzzy set of participants whose aim is reciprocal exchange of ideas for mutual enlightenment, & I should just stop talking about this.

That's the first time I've said that, but I'm sure not the last....  

But in any case, I thought I'd share this particular exchange. Maybe it will be clearer or more accessible than some of the others or simply increase the likelihood that someone who can get value from my views (very possibly by being able to see more clearly why he or she thinks I've made an error!) will find & get value out of these reflections on the nature of what sorts of study designs support inferences on "ideologically motivated reasoning" and asymmetry.

My friend:

I want to say that your research has found that more numerate people are more biased on both ends of the political spectrum, but my recollection is that what you find is actually that more numerate people do not believe more in the reality of climate change.  My question is: Have you looked at the interaction – e.g., done a median split on numeracy and then compared the polarization graphs between the numerate and innumerate?


I don't think what you've asked me to show you can support the inference that any particular form of reasoning proficiency ("science literacy," "numeracy," "cognitive reflection" etc.)  magnifies ideologically motivated reasoning "symmetrically" (let's say) with respect to ideology. 

But I'll show you what you asked to see first, before explaining why.

A. "Looking at" the magnification of polarization conditional on science comprehension

There are a variety of ways to graphically display what you are asking for--a view, essentially, of the differential in polarization at different levels of reasoning proficiency.

I think what I've done below -- splitting the "ideology" predictor & doing a lowess for each 1/2 of the sample separately in relationship to science comprehension -- is the best, or better in any case than splitting both continuous measures and giving you two pairs of %'s (for left-leaning & right-leaning at "below" & "above" avg); this way you get the information benefit of the continuous science-comprehension measure.


These are the same data from your slide 7.

With the lowess, one can see pretty readily that the gap between "left-" & "right-leaning" respondents gets progressively larger from -1 SD (16th percentile) to +1 SD (84th) on OSI_2.0 & then pretty much levels out.

(As you know, "OSI_2.0" is a 1-dimensional science-comprehension measure that consists of "science literacy," numeracy & cognitive reflection items. It was formed using a 2PL Item response theory model. For details, see 'Ordinary Science Intelligence': A Science Comprehension Measure for Use in the Study of Science Communication, with Notes on 'Belief in' Evolution and Climate Change.). 

B. But what are we looking at? 

So if one is trying to get the practical point across, this justifies saying things like, "polarization tends to increase, not abate, as individual with opposing political or cultural outlooks become more proficient in making sense of scientific information" etc.

But one can't on this basis infer that motivated reasoning is being magnified conditional on reasoning proficiency-- or as you put it, that "more numerate people are more biased on both ends of the political spectrum."

The question-- is human-caused climate change occurring?-- is a factual one that presumably has a correct answer. Thus, one "side" -- "liberals" or "conservatives" -- is presumably becoming more likely to get the correct answer as reasoning proficiency increases.

It is thus possible that motivated reasoning is increasing conditional on reasoning proficiency for the side that is becoming more likely to get the "wrong answer" but dissipating conditional on reasoning proficiency for the side that is becoming more likely to get the right answer!

That inference isn't logically compelled, of course.  If one is predisposed to believe something that happens to be true, then motivated reasoning will increase the likelihood of "getting the right answer."

But in that case, your getting the right answer won't prove you are smart; it will show only that you were lucky, at least on that particular issue.

The point, though, is that the evidence we are looking at above is equally consistent with the inference that motivated reasoning is being magnified by enhanced reasoning proficiency and the inference that ideologically motivated reasoning is "asymmetric" with respect to ideology. 

C. Observing what we really are trying to figure out

There is, I think, only one way to determine whether greater polarization conditional on greater reasoning proficiency is being caused by an ideologically symmetric (more or less) magnification of motivated reasoning: by looking at how people reason independently of whether they are getting the right answer.

What we need to see is how biased or unbiased the reasoning of those on both "sides" is as each side's members display greater reasoning proficiency.

I'll show you results from two studies that bear on this.

1. Motivated system 2 reasoning 

In the first (Kahan 2013), subjects evaluated "evidence" of the validity of the cognitive reflection test as a measure of "reflective & open-minded" reasoning. The experimental manipulation was the representation that those who score higher are more likely or instead less likely to accept evidence of human-caused global warming.

One might like to use a valid test of reflective reasoning (particularly an objective, performance based one like CRT, say, as opposed to the self-reporting ones like "need for cognition" that a fair number of researchers persist in using despite their dubious validity) to test the oft-asserted claim that "right-leaning" individuals are more "dogmatic" and "closed minded" etc. than "left-leaning" ones.

But if one is moved to selectively credit or discredit evidence of the validity of an open-mindedness test based on whether it supports the conclusion that those who share one's own ideology are "more open-minded and reflective" than are one's ideological opposites, one's own ideologically motivated reasoning will prevent one from being able to carry out such a test.

Indeed, if both "left-leaning" and "right-leaning" individuals display this effect, then we can conclude that both side are disposed to be unreflective & closed-minded in their thinking on this very issue.

That's what we see, of course:

If you can't make this out, click for enlarged version (and then by all means book an appointment with an optometrist!)

How likely subjects were to credit the evidence that the CRT was "valid" in this study was conditional on the interaction of experimental treatment and ideology: that is, the more conservative one becomes, the more likely one is to conclude the CRT is valid in the "believers score lower" condition and invalid in "skeptics score lower" one; vice versa as people become more liberal.

This inference doesn't depend on the CRT being an "open-mindedness" measure: the design would have worked just as well if the measure whose validity was being assessed was a fictional "open-mindedness" one.

Nevertheless, the effect observed is conditional on the subjects' CRT scores: the higher their score, the more likely they were to display this bias.

Accordingly, we can see that the form of critical-reasoning proficiency measured by CRT is indeed magnifying ideologically biased information processing.

2. Motivated numeracy

In the second study (Kahan et al. 2013), subjects performed a standard "covariance detection" problem.

The problem is diagnostic of a tendency to over-rely on heuristic reasoning of the sort that involves trying to infer causation from examining  the differential between the number of "got better" & "got worse" in only the fictional-study "treatment" condition.  That approach generates the wrong answer.  

As expected, in the control condition of our study (effectiveness of a new skin-rash treatment), there was a very strong correlation between correctly answering the problem and numeracy (indeed, one has to be at about the 90th percentile before there is even a 70% chance of getting it right).

But in the treatment condition of our study -- in which the outcome of a "gun control ban" experiment was manipulated-- subjects higher in numeracy were more likely to get the correct answer only if the data, properly interpreted, supported the position consistent with their own ideology.

So again, we see that critical reasoning is being used opportunistically: evidence is being assessed correctly depending on whether it supports an ideologically congenial outcome.

We see, too, that critical reasoning is magnifying this effect; subjects who are higher in numeracy are reliably summoning their greater proficiency to resist heuristic reasoning only when heuristic reasoning generates an uncongenial answer.

And finally, we are seeing that the effect is symmetric. Or in any case, we see it in both the left and right. (If you want to discuss whether it is "bigger" in the right, I'm happy to go into that; the answer is actually "no"-- although many people perceive that)!

3. Lesson: Manipulate motivating stake, measure "likelihood ratio"

Note that in both of these experiments, the "high proficiency" are "more polarized" than their "low proficiency" counterparts. They are "better," more reliable, in fitting the evidence to their ideological predispositions.

If this is how people process information in the world, then we will see, in an observational study, that those higher in proficiency are more polarized. We'll be able to infer, moreover, that this is the result of the magnification of biased information processing & not a result of one "side" getting the "right answer."

Indeed, the whole point of the experimental design was to unconfounding quality of reasoning from "right answer." This was done, in effect, by manipulating the motivational stake of the subjects to credit one and the same piece of evidence.

In Bayesian terms, we are demonstrating that subjects opportunistically adjust the likelihood ratio in response to an identity-protective motivation unrelated to assessing the truth-value weight of the new information (Kahan 2015).

This is a more general point: studies that purport to show "motivated reasoning" or "biased assimilation" by looking at the equivalent of "posterior probabilities" are almost always invalid. They are consistent with the inference that "one side is biased," or even that "neither side is," because differences in opinion after review of evidence is consistent with different priors or pre-treatment effects (consideration of the evidence in question or its equivalent) before the study. One should manipulate the stake the subjects have in the outcome & assess how that effects the likelihood ratio assigned to one and the same piece of evidence -- conceptually speaking (Kahan 2013).



Weekend update: More on HPV vaccine disaster (Science of Science Communication 2.0, Session 1)

Tamar Wilner has a great "reaction paper" response to the Session 1 materials on the "HPV vaccine disaster."  She asks, provocatively, whether the "media ... manufacture[d] the HPV vaccine controversy" and then answers, moderately, "well, probably not" while flagging difficult issues for science-communication journalists about their role in covering science issues that become connected to cultural controversy.

Read Tamar's post for yourselves-- & comment, if you have anything to add.

I've posted my comment, both below, as a comment, and on the Session 1.1 post, and at Tamar's site.  I'm gonig to close comments here so that the discussion doesn't get too fractured.

Read the rest at Tamar Wilner's site!


National Academy Conference on Science Communication & GMOs

This is where I am today.

Tune in via webcast!


Science of Science Communication 2.0, Session 1.1: The HPV Vaccine Disaster

page 1 of the course materials-- click it!Okay, so here is the first post for the "virtual" Science of Science Communication course 2.0. Actually, I'll be teaching/learning/attending the first "real world" session in about 30 mins.  

Today's readings are in the nature of a "case study" of the introduction of the HPV vaccine in the U.S. & its status today. The material below is in the nature of a "set up" for discussion, which I encourage people to have whereever they want but also in the comments section.  

I'm designating this "Session 1.1" in anticipation that I might myself post something-- in the nature of a "follow up" -- in which case I'll designate "Session 1.2."  Or maybe I'll do something else, who knows.

BTW check out this super cool & generous invitation if you are looking for "virtual" classmates & course materials!!

The introduction of the HPV vaccine in the US-- or the cost of being innocent & ignorant of the science of science communication. . . .

1. Merck’s application for “fast-track” review of female-only shot. It is late 2005. Merck, the manufacturer of the HPV vaccine Gardasil, has applies for “fast-track” FDA approval of a female-only shot.

HPV—the human papilloma virus—is a sexually transmitted pathogen. Exposure is widespread: some 45% of women in their early 20s have been infected. A comparable percentage of men almost certainly have been, too, although there is at this time no effective test for males.

HPV causes genital warts in some but not all infected individuals.

It is also the sole cause of cervical cancer. A diseases that can normally be detected at an early stage by a routine pap smear and thereafter successfully treated, cervical cancer nevertheless claims the lives of 3,000 women per year in the U.S. (many more in undeveloped countries that lack effective public health systems).

Clinical tests show that Gardasil confers immunity against 70% of the strains of HPV that can cause cervical cancer. This evidence furnishes logical reason to believe that widespread immunization would reduce cervical cancer rates, although the vaccine is in fact too new, and experience with it in nations where it is already in use too limited, for that proposition to have been empirically tested.

The role of HPV in causing cervical cancer is the basis for Merck’s application for “fast track” review, which is available only for drugs that furnish an “unmet medical need” for treatment or prevention of a “serious disease.” The link to cervical cancer is also why the “fast track” application is for a female-only shot: genital warts are not considered a “serious disease,” and while HPV might cause oral or anal cancer in men, there is at this time insufficient evidence to be sure.

If put on the “fast track,” Gardasil will likely be approved for use for women within six months. The FDA review process would otherwise be expected to take three additional years. Within that time frame, in fact, the FDA is likely to approve for males and females both Gardasil and Cervarix, an HPV vaccine manufactured by GlaxoSmithKline and already approved for use in Europe.

2. Health risks? Clinical trials suggest no reason to believe Gardasil poses a risk of dangerous side-effects. Some critics question the quality of this evidence, however, noting the recent withdrawal of Merck’s anti-inflammatory Vioxx based on evidence, known but not initially acknowledged by Merck, that showed the drug increased the risk of heart attacks and strokes.

Other critics suggest that widespread HPV immunization could have perverse behavioral consequences. To be effective, immunization should occur during adolescence, before an individual is likely to have become exposed to the disease through sexual activity. Some groups, including social conservative and religious ones, have voiced concern that immunization will generate a sense of false security in teenage girls, who will therefore be more likely to engage in unprotected sex, exposing themselves to a higher risk of pregnancy or other STDs. There is currently no evidence one way or the other on whether HPV immunization of adolescent girls would have any such effects.

3. The proposed legislative initiative. In addition to seeking fast-track approval of Gardasil, Merck is known to be organizing a nationwide lobbying campaign aimed at securing legislation adding the HPV vaccination to the schedule of universal childhood immunizations treated as a condition of public-school enrollment.

As part of this effort, Merck has reached out to women’s health advocacy groups. These groups strongly support making the HPV vaccine available in the U.S. Merck has proposed that these groups play a lead role in the company’s lobbying campaign, which would be funded by Merck. Merck is also understood to be searching for social conservatives to participate in the campaign.

4. Physicians’ views. There is every reason to believe physicians will view the availability of an HPV vaccination as a very positive development. No major U.S. medical association, however, has taken a position on either Merck’s fast-track proposal or on adding the HPV vaccine to states’ school-enrollment immunization schedules.

At least some physicians, however, have voiced criticism of how the vaccine is being introduced. They assert that Merck’s fast-track application and its planned nationwide legislative campaign are economically motivated: Merck’s goal, they have argued (in various fora, including medical journal commentaries), is to establish a dominant position in the market before the FDA approves of GlaxoSmithKline’s rival Cervarix vaccine. Whatever public health benefits might be associated with accelerating the speed with which Gardasil is approved and HPV vaccine added to universal vaccination schedules, these commentators have warned, will be offset by the increased risk of a political backlash.

5. Political controversy? At this point, there is no meaningful dispute over Gardasil. Indeed, only a minute fraction of the U.S. population has ever heard of the vaccine or even HPV for that matter.

Nevertheless, the prospect of controversy has already been anticipated in the national media. A government-mandated STD shot for adolescent girls, these sources predict, is certain to provoke confrontation between women’s rights groups and religious and social conservatives.

Aside from some women’s’ health groups, the only other advocacy group to address the HPV vaccine is the Family Research Council. Committed to protecting religious values in American life, FRC has played a major role in opposing public-school instruction on birth control. The FRC has stated that it does not oppose—indeed, “welcomes”—the introduction of the HPV vaccine, but views state-mandated vaccination as interfering with parental control of their children’s’ health and their sexual behavior.

5. The HBV vaccine. The HPV vaccine would not be the first STD immunization to be placed on states’ school-enrollment vaccination schedules. A decade ago the FDA approved the HBV vaccine for hepatitis-b, a sexually transmitted disease that causes a lethal form of liver cancer. The CDC quickly recommended that the vaccine, which had been approved for both males and females, be added to the list of universal childhood immunizations. Within several years, almost every state had added the HBV vaccine to its mandatory-immunization schedule via regulations issued by state public health officials, the conventional—and politically low-profile process—for updating such provisions. The addition of the HBV vaccine to the state schedules generated no particular controversy, and the nationwide vaccination rate for HBV, like other childhood immunizations, has consistently been well over 90%.

6. “Public acceptance” research. Public health researchers have conducted studies specifically aimed at assessing the public acceptability of an adolescent HPV shot. These studies, which consist of surveys of parents with adolescent children, uniformly report that parents say they are unfamiliar with the HPV vaccine but will have their children immunized if their pediatricians recommends doing so.

Issues. Should the FDA grant Merck’s application for fast-track review? Should Merck withdraw it? Should women’s’ advocacy groups agree to participate in the company’s nationwide legislative campaign? What position, if any, should medical professional associations take? Is the position of social conservative groups like the FRC relevant to these questions?


The "disentanglement research program": a fragment

From something I'm working on -- & closely related to what is described here, of course.

The "disentanglement project": an empirical research program

“Evolution” refers not only to a scientifically grounded account of the natural history of life on earth but also to a symbol in relationship to which people's stances signify membership in one or another cultural group.  The confounding of the former and the latter are at the root of a cluster of related societal problems. One is simply how to measure individual comprehension of evolutionary science and science generally. Another is how to impart collective knowledge on terms that avoid needlessly conditioning its acquisition on an abandonment or denigration of cultural commitments collateral to science.  And a final problem is how to protect the enterprise of acquiring, assessing, and transmitting knowledge from becoming a focal point for cultural status competition corrosive of the reciprocal benefits that science and liberal democratic governance naturally confer on one another.  This paper discuss the “disentanglement project,” an empirical research program aimed at identifying an integrated set of practices for unconfounding the status of evolution as a token of collective knowledge and a symbol of cultural identity within the institutions of the liberal state. 


So you want to meet the 'Pakistani Dr'? Just pay a visit to the Kentucky Farmer

I now realize that a lot of people think that Hameed’s Pakistani Dr—who without apparent self-contradiction “disbelieves” in evolution “at home” but “believes” in it at work—is a mystery the solution to which must have something to do with his living in Pakistan (or at least having grown up and gone to school there before moving to the US to practice medicine (Everhart & Hameed (2013)).

That’s a big mistake! 

Indeed, in my view it gets things exactly backwards: what makes the Pakistani Dr so intriguing, & important, is that he is the solution to mysteries about the psychology of a lot of people born & bred right here in the U.S. of A!

One place where you can find a lot of Pakistani Drs, e.g., is in the South & Midwest, where their occupation of choice is farming.

Public opinion studies consistently find that farmers are deeply skeptical of climate change (e.g., Prokopy et al. 2014).

Which is to say, when you ask them if they believe human fossil-fuel burning is heating up the planet, they say, “Heck no! Don’t give me that Al Gore bull shit!”

But that’s what happens, you see, if you ask them about what they believe “at home.” 

If you ask them what they believe “at work,” where they must make practical decisions based on the best available evidence, then you are likely to get a completely different answer!

Or so a group of researchers recently reported in an amazingly cool study published in the Journal of Agricultural and Applied Economics (Rejesus, Hensley, Mithcell, Coble & Knight 2013).

Analyzing the results of an N = 1380 USDA-conducted survey of farmers in Mississippi, North Carolina, Texas, and Wisconsin, RHMCK reported that less than 50% in each state agreed with the statement, “I believe human activities are causing changes in the earth climate.”

Indeed, only a minority—around a quarter of the respondents in Mississippi, Texas, and Wisconsin; a bit over a third in North Carolina—indicated that they “believe climate change has been scientifically proven” at all.

But when these same respondents answered questions relating to how climate change would affect farmers, only a small minority expressed any doubt whatsoever that the impact would be considerable.

For example,

nearly 60% of producers in Mississippi and Texas, states where scientific proof of climate change is typically not agreed to, believe there will be some change in crop mix resulting from climate change.

Majorities in Mississippi (55%) and North Carolina (56%) also indicated that it was likely that, in response to climate change, farmers in their state would be buying more crop insurance to protect them from the increased variability in yields associated with a higher incidence of extreme weather events.

Of course, you can insure yourself from risks only if the benefits exceed the expected costs of enduring them. A lot of farmers think that farming won't be profitable be in the future-- thanks to climate change.

In North Carolina (57%) and Texas (51%), a majority of the respondents indicated that they thought it was either “likely” or “extremely likely” that climate change would force some farmers out of business.

In none of the states did anything even close to a majority indicate that they thought it was either "unlikely” or “extremely unlikely" that farmers would resort to greater crop rotation, increased insurance coverage, or simply quitting the business altogether in response to climate change.

Obviously, some fraction of the positive responses to these questions came from the minority of farmers in these states who indicated that they do believe climate change is "scientifically proven." 

But it turns out the views of “believers” and “disbelievers” on these matters didn’t vary by much.

  • Likely that farmers will resort to crop diversification as a result of climate change
    Believers: 51% agree 
    Disbelievers: 47% agree

  • Likely that farmers will be driven out of business by climate change:
    Believers: 50% agree
    Nobelievers: 47% agree

  • Likely that farmers will acquire greater crop insurance protection to deal with climate change:
    Believers: 56% agree
    Nonbelievers: 45%, agree

These self-report data, moreover, match  up quite well with behavioral data, which show that climate-skeptical farmers are already adopting practices (like no-till planting, new patterns of crop rotation, adjustments in growing season projections) in anticipation of climate impacts.

Business actors, moreover, are rushing in to profit from the willingness of farmers to pay for services and technologies that will help them weather climate change. Just ask Monsanto, which is perfectly happy to proclaim its belief in climate change, how excited farmers are about its climate-change resistant GM crops, as well as the company’s new business ventures in supplying climate data and climate-change crop insurance.

How to make sense of this?

 The most straightforward answer is the one set forth in the Measurement Problem (Kahan in press): whether people say they “believe” or “disbelieve in” human-caused climate change is not a valid measure of what they know about climate science; rather it is simply an indicator ofidentity on a par with people’s responses to items that solicit their cultural values, their right-left political outlooks, their religiosity or whathaveyou.

Farmers who express their cultural identity by saying they “disbelieve in” human-caused climate change actually do know a lot about it—much more, probably, than the average person who says he or she does “believe in” climate change but who it turns out is highly likely to think that global warming is caused by sulfur emissions and will stifle photosynthesis in plants.

What do "believers" & "nonbelievers" in human-caused climate change know about climate science? Not much! Click & see for self.In the Measurement Problem study, I used a climate-literacy assessment instrument the items of which were carefully calibrated to disentangle or unconfound "identity" and "knowledge."

To me, the RHMCK results suggest that one can unconfounded "identity" and "knowledge" in an equivalent way with items that, unlike the cultural-identity-eliciting "do you believe in climate change" item, effectively assessed what farmers understood the evidence of climate change to signify for their vocation.

Cool, okay.

But the much more difficult question is—what exactly is going on in the heads of those farmers who clearly comprehend the evidence but who say they “don’t believe in” climate change?

This is exactly what the Pakistani Dr has been trying, so patiently, to help us figure out!

If he hadn't been so persistent in trying to pierce through the dense armor of my incomprehension, I would have had nothing more to say than what I just did—viz., that what a farmer in Mississippi, Texas, North Carolina, or Wisconsin says he “believes” about climate change measures something entirely different from what he “knows” about it.

But now, thanks to what the Dr has taught me, I have a hunch that the “climate change” that that farmer doesn’t “believe in” & the "climate change” he does “believe in” are, as the Dr would say, "entirely different things!"

“Climate change,” certainly, can be defined with reference solely to a state of affairs, or the evidence for it.

But as an object of belief or knowledge, climate change can’t be defined that way.

It’s just plain weird, really, to imagine that if we could somehow take a person, unscrew the lid of his mind, turn him upside down, and shake him a bit, a bunch of discrete “beliefs” would fall onto the ground in front of us. 

What we believe or know—the objects of those intentional states—don’t have any existence independently of what we do with them.  The kinds of things we do, moreover, are multiple and diverse—and correspond to the multiple and diverse roles our integrated identities comprise.

The Pakistani Dr is an oncologist and a proud member of a science-trained profession.  His belief in evolution enables him to be those things.

He is also a devout Muslim.  His disbelief of evolution enables him to be that—when being that is what he is doing.

There’s no conflict!, he keeps insisting. The evolution he “accepts” and the evolution he “rejects” are entirely different things—because the things he is doing with those intentional states are entirely different, and, fortunately for him, perfectly compatible with each other in the life he leads.

This is Scott Travis, the Kentucky farmer. Click to have a conversation. He can teach you something.Well, for the Kentucky (Mississippi/Texas/North Carolina/Wisconsin/Indiana  etc.) farmer, there are two climate changes: the one he rejects to protect his standing in a particular cultural community engaged in an ugly status competition with another whose members’ “belief in” climate change serves the same function; and the one the Kentucky farmer accepts in the course of using his reason to negotiate the challenges of his vocation.

Sadly, the Kentucky farmer lives in a society that makes reconciling the diverse roles that he occupies—the different things he is enabled to do—by “believing in” one “climate change” and “disbelieving in” another much less straightforward, routine--boring even--than what the Pakistani Dr does when he accepts one evolution and reject another.

This is a big problem.  Not just for the Kentucky farmer but for all those who live in the society so many of whose members find what the Kentucky farmer is doing with his reason not only incomprehensible but simply intolerable. 


Everhart, D. & Hameed, S. Muslims and evolution: a study of Pakistani physicians in the United States. Evo Edu Outreach 6, 1-8 (2013).

Kahan, D. Climate Science Communication and the Measurement Problem. Advances in Pol. Psych (in press).

Prokopy, L.S., Morton, L.W., Arbuckle, J.G., Mase, A.S. & Wilke, A. Agricultural stakeholder views on climate change: Implications for conducting research and outreach. Bulletin of the American Meteorological Society  (2014).

Rejesus, R.M., Mutuc-Hensley, M., Mitchell, P.D., Coble, K.H. & Knight, T.O. US Agricultural Producer Perceptions of Climate Change. Journal of Agricultural and Applied Economics 45 (2013).




"Science of Science Communication" course, version 2.0

This semester I will be teaching my "science of science communication" course for 2nd time.  

I got my act together this time, too, and had the course, which is a Psychology Dept graduate offering, cross-listed in the School of Public Health, the School of Forestry and Environmental Studies, plus the Law School.  The value of the "science of science communication," it seems to me, depends entirely on the function it can perform in integrating the production of scientific knowledge & science-informed policymaking, on the one hand, with scientific knowledge of the processes by which people come to know what is known by science, on the other. So obviously, offerings like this shouldn't be "in the course catalog" of only decision-science or communication-science disciplines.... 

Anyway, like last time, I'm going to see if I can offer a "virtual" counterpart of the course via this blog.

I'll post course materials, as they become available, here.  Unfortunately, I can't post the readings themselves, since access to portions of them is restricted to users covered by one or another of Yale University's site licenses or subscriptions to various commercial content providers. But I will post the reading lists & various "open access" materials.

After each "real space" session, though, I'll post some sort of synopsis or argument or whatever as a "starter" for discussion.  People can weigh in based on their access to that, plus whatever else they can get their hands on -- including materials other than those assigned to students enrolled in the course at Yale!

This worked pretty well last time, except I wasn't as conscientious as I should have been in posting "starters."

This time I'll do better!

Below I've posted the "course catalog" description of the course, plus the "manifesto" that introduces the course requirements & topics etc.


The Science of Science Communication, PSYC 601b, FES 862b, HPM 601, LAW 21141. The simple dissemination of valid scientific knowledge does not guarantee it will be recognized by non-experts to whom it is of consequence. The science of science communication is an emerging, multidisciplinary field that investigates the processes that enable ordinary citizens to form beliefs consistent with the best available scientific evidence, the conditions that impede the formation of such beliefs, and the strategies that can be employed to avoid or ameliorate such conditions. This seminar surveys, and makes a modest attempt to systematize, the growing body of work in this area. Special attention is paid to identifying the distinctive communication dynamics of the diverse contexts in which non-experts engage scientific information, including electoral politics, governmental policy making, and personal health decision making.

* * *

1. Overview. The most effective way to communicate the nature of this course is to identify its motivation.  We live in a place and at a time in which we have ready access to information—scientific information—of unprecedented value to our individual and collective welfare. But the proportion of this information that is effectively used—by individuals and by society—is shockingly small. The evidence for this conclusion is reflected in the manifestly awful decisions people make, and outcomes they suffer as a result, in their personal health and financial planning. It is reflected too not only in the failure of governmental institutions to utilize the best available scientific evidence that bears on the safety, security, and prosperity of its members, but in the inability of citizens and their representatives even to agree on what that evidence is or what it signifies for the policy tradeoffs acting on it necessarily entails.

This course is about remedying this state of affairs. Its premise is that the effective transmission of consequential scientific knowledge to deliberating individuals and groups is itself a matter that admits of, and indeed demands, scientific study.  The use of empirical methods is necessary to generate an understanding of the social and psychological dynamics that govern how people (members of the public, but experts too) come to know what is known to science. Such methods are also necessary to comprehend the social and political dynamics that determine whether the best evidence we have on how to communicate science becomes integrated into how we do science and how we make decisions, individual and collective, that are or should be informed by science.

Likely you get this already: but this course is not simply about how scientists can avoid speaking in jargony language when addressing the public or how journalists can communicate technical matters in comprehensible ways without mangling the facts.  Those are only two of many science communication” problems, and as important as they are, they are likely not the ones in most urgent need of study (I myself think science journalists have their craft well in hand, but we’ll get to this in time).  Indeed, in addition to dispelling (assaulting) the fallacy that science communication is not a matter that requires its own science, this course will self-consciously attack the notion that the sort of scientific insight necessary to guide science communication is unitary, or uniform across contexts—as if the same techniques that might help a modestly numerate individual understand the probabilistic elements of a decision to undergo a risky medical procedure were exactly the same ones needed to dispel polarization over climate science! We will try to individuate the separate domains in which a science of science communication is needed, and take stock of what is known, and what isn’t but needs to be, in each.

The primary aim of the course comprises these matters; a secondary aim is to acquire a facility with the empirical methods on which the science of science communication depends.  You will not have to do empirical analyses of any particular sort in this class. But you will have to make sense of many kinds.  No matter what your primary area of study is—even if it is one that doesn’t involve empirical methods—you can do this.  If you don’t yet understand that, then perhaps that is the most important thing you will learn in the course. Accordingly, while we will not approach study of empirical methods in a methodical way, we will always engage critically the sorts of methods that are being used in the studies we examine, and I from time to time will supplement readings with more general ones relating to methods.  Mainly, though, I will try to enable you to see (by seeing yourself and others doing it) that apprehending the significance of empirical work depends on recognizing when and how inferences can be drawn from observation: if you know that, you can learn whatever more is necessary to appreciate how particular empirical methods contribute to insight; if you don’t know that, nothing you understand about methods will furnish you with reliable guidance (just watch how much foolishness empirical methods separated from reflective, grounded inference can involve).


Humans using statistical models are embarrassingly bad at predicting Supreme Court decisions....

Part of Lexy's brain. From Ruger et al. (2004)Demoralizingly (for some people; I don't mind!), computers have defeated us humans in highly discerning contests of intellectual acuity such as chess and Jeopardy.

But what about prediction of Supreme Court decisions?  Can we still at least claim superiority there?

Well, you tell me.

In 2002-03, a group of scholars organized a contest between a computer and a diverse group of human "experts" drawn from private practice and the academy (Ruger, Kim, Martin & Quinn 2004).

Political scientists have actually been toiling for quite a number of years to develop predictive models for the Supreme Court.  The premise of their models is that the Court’s decisionmaking can be explained by “ideological” variables (Edwards & Livermore 2008).

In the contest, the computer competitor, Lexy (let’s call it), was programmed using the field’s state-of-the-art model, which in effect tries to predict the Court's decisions based on a combination of variables relating to the nature of the case and the parties, on the one hand, and the ideological affinity of individual Justices as reflected by covariance in their votes, on the other.

For this reason, the contest could have been seen (often is described) as one that tested the political scientists’ “ideology thesis” against “formal legal reasoning.” 

But in fact, that's a silly characterization, since the informed professional judgment of genuine Supreme Court experts would certainly reflect the significance of "Justice ideology" along with all the other influences on the Court’s decisionmaking (Margolis 1987, 1996; Llewellyn, 1960).

In any case, Lexy trounced those playing the role of “experts” in this contest.  The political scientists' model correctly predicted the outcome in 75% of the decisions, while the experts collectively managed only 59% correct . . . .

The result was widely heralded as a triumph for both  algorithmic decisionmaking procedures over expert judgment & for the political scientists’ “ideology thesis."

But here’s the problem: while Lexy “did significantly better at predicting outcomes than did the experts” (Ruger et al. 2004, p. 1152), Lexy did not perform significantly better than chance!

The Supreme Court’s docket is discretionary: parties who’ve lost in lower courts petition for review, and the Court decides whether to hear their cases.

It rejects the vast majority of review petitions—96% of the ones on the "paid" docket and 99% of those on the “in forma pauperis” docket, in which the petitioner (usually a self-represented prisoner) has requested waiver of the filing fee on grounds of economic hardship.

Not surprisingly, the Court is much more likely to accept for review a case in which it thinks the lower court has reached the wrong result.

Hence, the Court is far more likely to reverse than to affirm the lower court decision. It is not unusual for the Court to reverse in 70% of the cases it hears in a Term (Hofer 2010).  The average Supreme Court decision, in other words, is no coin toss!

Under these circumstances, the way to test the predictive value of a statistical model is to ask how much better someone using the model would have done than someone uniformly picking the most likely outcome--here, reversal-- in all cases (Long 1997, pp. 107-08; Pampel 2000, p. 51).

In the year in which Lexy squared off against the experts, the Court heard only 68 cases.  It reversed in 72% of them. 

Thus, a non-expert who knew nothing more than that the Supreme Court reverses in a substantial majority of its cases, and who simply picked "reverese" in every case, would have correctly predicted 72% of the outcomes.  The margin between her performance and Lexy's 75% -- a grand total of two fewer correct predictions -- doesn't differ significantly (p = 0.58) or practically from zero. 

A practical person, then, wouldn't bother to use Lexy instead of just uniformly predicting "reverse."

None of the “holy cow!” write-ups on Lexy’s triumph—which continue to this day, over a decade after the contest—mentioned that the algorithm used by Lexy had no genuine predictive value.

But to be fair, the researchers didn't mention that either.

They noted that the the Supreme Court had reversed in 72% of its cases only in footnote 82 of their 60-page, 122-footnote paper. And even there they didn't acknowledge that the predictive superiority of their model over the "72% accuracy rate" one would have achieved by simply picking "reverse" in all cases was equivalent—practically and statistically—to chance.  

Instead, they observed that the Court had in some "recent" Terms reversed less than 70% of the granted cases. The previous Terms were in fact the the source of the researchers' "training data"--the cases they used to construct their statistical model. They don't say, but one has to believe that their "model" did a lot better than 75% accuracy when it was "fit" retrospectively to those Terms' cases-- or else the researchers would surely have tinkered with its parameters all the more.  But that the resulting model performed no better than chance (i.e, than someone uniformly picking "reverse," the most likely result in the training data) when applied prospectively to a new sample is a resounding verdict of “useless” for the algorithm the researchers derived by those means.

Sure, the “experts” did even worse, and that is embarrassing: it means they'd have done better by not "thinking" and instead just picking "reverse" in all cases, the strategy a non-expert possessed only of knowledge of the Court's lopsided proclivity to overturn lower court decisions would have selected.

But the "experts'" performance—a testament perhaps to their hubristic overconfidence in their abilities but also largely to the inclusion of many law professors who had no general specialty in Supreme Court decisionmaking —doesn’t detract from the conclusion that the statistical model they were up against was a complete failure.

What’s more, I don’t think there’s anything for Lexy or computers generally to feel embarrassed about in this matter. After all, a computer didn’t program Lexy; a group of humans did.

The only thing being tested in that regard was the adequacy of the “ideology thesis”-prediction model developed by political scientists.

That the researchers who published this study either didn’t get or didn’t care that this model was shown to perform no better than chance makes them the ones who have the most to be embarrassed about.


Edwards, H.T. & Livermore, M.A. Pitfalls of empirical studies that attempt to understand the factors affecting appellate decisionmaking. Duke LJ 58, 1895-1989 (2008).

Hofer R. Supreme Court Reversal Rates: Evaluating the Federal Courts of Appeals, Landslide 2, 10 (2010). 

Llewellyn, K.N. The Common Law Tradition: Deciding Appeals (1960).

Long, J.S. Regression models for categorical and limited dependent variables (Sage Publications, Thousand Oaks, 1997).

Margolis, H. Dealing with risk : why the public and the experts disagree on environmental issues (University of Chicago Press, Chicago, IL, 1996).

Margolis, H. Patterns, Thinking, and Cognition (1987).

Pampel, F.C. Logistic regression : a primer (Sage Publications, Thousand Oaks, Calif., 2000).

Ruger, T.W., Kim, P.T., Martin, A.D. & Quinn, K.M. The Supreme Court Forecasting Project: Legal and Political Science Approaches to Predicting Supreme Court Decisionmaking. Columbia Law Rev 104, 1150-1210 (2004).

Long, J.S. Regression models for categorical and limited dependent variables (Sage Publications, Thousand Oaks, 1997).




"...but that just doesn't happen!..." Or: "Who is the 'Pakistani Dr' now?"--a fragment on the professional judgment of law professors

 From correspondence with a friend & collaborator of preternatural intelligence and critical reflection; in response to her rejection of a "proof," presented in the form of a computer simulation, of the "impossibility" of using "rules of evidence" to conform adversary adjudication to the goal of rational truth seeking:

Extravagance.  "Oh, but this just doesn't happen -- look at the cases!"  Really?  It's in the nature of the phenomenon not to be directly observable. If we are committed to rational truth seeking, we should be trying to figure out how to create observations of influences we wouldn't detect in the normal course but that in fact undermine our conclusions about what we are seeing.  In any case, everything I have ever observed (when I summon the will to observe; like you, like everyone else, I am trained not to) tells me that this is exactly what effective trial advocacy is about.  A trial is not a conveyor belt onto which pieces of evidence are added to be processed down the line by a Bayesian proof aggregator.  It is a violent struggle from the start to impose a narrative template, to which the factfinder can be expected to mold every piece of proof.  The forms of information processing that lawyers anticipate and jockey to grab hold of and point in the desired direction are hostile to accurate factfinding -- deeply hostile to it.  The idea that "trials work just fine, especially with a little fine tuning w/ rules of evidence that anticipate cognitive biases" is a 2nd order form of flawed information processing that occurs in those officially certified to play the role of critical examiners of the system; that they end up saying exactly that, moreover, helps to insulate the flaws even more securely from the truly unbearable realization that we are making people's lives depend on an arbitrary game.  Or in any case, this what I believe "at home"; "at work" I, too, believe the system is perfectly rational.



More on Hameed's "Pakistani Dr" -- "explaining contradictory beliefs" begs the question

Just because I haven't been writing about him all the time in this forum doesn't mean I've stopped thinking about Hameed's "Pakinstani Dr," the paradigm case of "dualism" or "knowing disbelief" or whathaveyou.  On the contrary, longish periods of inactivity in this blog can be explained by the days at a time I spend  in bed (except for a 12-mile run @ about 10:30 or 11:00 pm), unable to overcome the sense of anomie I experience as a result of not having a satisfactory account (just a decent provisional one, of course) of what is going on in his head .... But today I'm up -- in part b/c Ann Richards was biting my nose (she should learn to feed herself; is that too much to ask?) --& engaged in a bit of email correspondence in which I described the state of my thinking about the "knowing disbelief/dualism" issue this way to a colleague: 

I'm pretty obsessed right now w/ trying to comprehend/identify/test the mechanisms that can generate in people's minds coexisting states of belief & nonbelief in evolution or climate change. The paradigm case would be Hameed's Pakistani Dr., who "disbelieves in" evolution "at home" but "believes in" it "at work."

All the explanations that people are inclined to give-- ones involving  "compartmentalization & dissonance avoidance," insincerity,  "misconstrual," "divided selves" etc-- assume that what's in need of explanation is the holding of contradictory beliefs.  I think that's a mistake -- or at least begs the question.

The question is how to individuate  the "factual proposition" (or for simplicity, just "fact") that is the object of the subject's "belief" or knowledge.  

The standard explanations of the Pakistani Dr  all assume that the "fact" is defined exclusively w/ reference to some state of affairs external to or independent of the subject, that is, the individual who "knows" it.  The referent for "human evolution" is "the natural history of human beings as described by evolutionary science."  So if someone "believes" & "disbelieves" in human evolution, they are manifesting opposed or contradictory intentional states toward the fact of human evolution.

My hunch is that the "fact" that is object of knowledge or belief must in addition be defined in relation to the contribution that knowing or believing it makes to some end or goal of the subject.

Individuals have many goals. More than one can be bundled with a fact defined w/ reference to some external state of affairs.

E.g., the Pakistani Dr, an oncologist, can "know" or "believe in" evolution in order to determine the risk his patient will develop breast cancer; he can also "know" or "believe in" it in order to participate in the sense of identity he experiences as a member of a profession that generates knowledge beneficial to humanity ("stem cell research-- brilliant!")

It turns out that the Pakinstani Dr also "disbelieves in" human evolution,  knows it to be false, in order to be a member of a community that subscribes to an alternative account of the natural history of human beings.  

So is there a "contradiction" in his "beliefs"?

Well, luckily for him, the Pakistani Dr's goal or end of being a member of that community is not incompatible with the goal of doing oncology or being a member of the medical profession (things could surely be otherwise--are, sadly, becoming otherwise in Europe, Hameed shows in his most recent paper).  Thus, for the Pakistani Dr there is no contradiction between his "belief in" & "disbelief in" in evolution when the objects of those mental states are defined jointly by reference to "the natural history of human beings as described by evolutionary science" and by the goals that are promoted by believing/disbeliving in that.  

He keeps trying to tell us this: "yes, yes," they both relate to "Darwin's theory," he notes with exasperation, but the "evolution" he "accepts" and the "evolution" he "rejects" are "entirely different things!"  We keep staring back uncomprehendingly...

I think it is important to get straight about this pragmatic-dualist account of the Pakistani Dr's beliefs -- about how it differs from all the ones that assume "contradiction" & try to explain it; about whether it is right; about what to think of the role it plays and can play in socieites that are trying to negotiate "Popper's Revenge..."

Likely someone somewhere has worked all this out already! I keep asking people for directions; they do helpfully point me down one path or another -- & I'm grateful. But no doubt as a result of my own imperfect navigation skills, I still feel very much lost ...

What “bodycams” can and can’t be expected to do. . . plus coolest study of the year

I definitely favor police “bodycams” as a means of promoting  greater police accountability to the public and greater public confidence in their police.

But there’s a pretty straightforward reason why bodycams won’t prove to be a silver bullet in the effort to subdue societal conflict over excessive police force: perceptions of who did what to whom in such disputes are among the class of factual beliefs influenced by cultural cognition.

When it comes to the impact of cultural cognition, there’s nothing special about brute sense impressions.

Indeed, the foundational study of motivated reasoning—of which cultural cognition is one form—involved distortion of visual perception.  Described in Hastorf & Cantril's 1954 paper, “They Saw a Game,” the experiment showed that students from rival colleges formed opposing perceptions of disputed officiating calls featured in a film of a football game between their schools.  The students' stake in experiencing solidarity with their classmates, researchers concluded, had unconsciously influenced what they saw when viewing the film.

Whether the police can be trusted to refrain from abusing their authority turns on a host of disputed facts symbolically identified with membership in important cultural groups.  Accordingly, the stake that individuals have in experiencing and expressing solidarity with those groups can likewise be expected to unconsciously shape what they see when they view filmed depictions of violent police-citizen interactions.

People who remember the divided reactions to the Rodney King video probably have a sense of that—although, in fact, when people are experiencing this sort of cognitive dynamic, they tend to notice its impact only on those with whom they disagree and not on themselves (Robinson,  Keltner, Ward,  & Ross 1995).

But there is also experimental evidence corroborating the impact of cultural cognition on visual perceptions of behavior in police-citizen confrontations.

These include two CCP studies:  They Saw a Protest (Kahan, Hoffman,  Braman,  Evans, &  Rachlinski 2012) which involved a film of police and political protestors who were variously characterized as demonstrating against abortion rights or against the military’s “don’t ask, don’t tell policy”; and Whose Eyes Are You Going to Believe (Kahan, Hoffman & Braman 2009), which involved film shot from inside a police cruiser that deliberately rammed that of a fleeing suspect.

In both instances, the studies found that what the subjects reported observing --protestors blocking access to a building or people shamed into avoiding entry; a driver veering wildly into lanes of oncoming traffic or police "taking out" a motorist for defying their will -- depended on the subjects' cultural identities. 

But the coolest study on motivated reasoning and perceptions of police force was featured in an article that just came out,  Justice is not blind: Visual attention exaggerates effects of group identification on legal punishment (Granot, Balcetis,  Schneider, & Tyler 2014).

Indeed, GBST  is for me the run-away winner in the contest for “coolest study of the year.”

Actually, GBST reported the results of two related  studies. In one, the researchers correlated perceptions of a violent citizen-police encounter with subjects’ moral predispositions toward the police generally.

In the other, the researchers correlated the subjects’ group membership with perceptions of the behavior of two brawling private citizens, who were identified variously as belonging either to the subjects’ group or to a rival one.

The super cool part of the study was that the researchers used an eye-tracking instrument to assess the predicted influence of motivated reasoning on the perceptions of the subjects.

Collected without the subjects’ awareness, the eye-tracking data showed that subjects fixed their attention disproportionately on the actor they were motivated to see as the wrongdoer—e.g., the police officer in the case of subjects predisposed to distrust the police in study 1, or the citizen identified as an “out-group” member in study 2.


Before reading this study, I would have assumed the effect of cultural cogntion was generated in the process of recollection: that people were fitting bits and pieces of recalled images onto narrative templates featuring police force and the like (cf. Penningon & Hastie 1991, 1992)

But GBST's findings suggest the dynamic that generates opposing perceptions in these cases commences much earlier, before the subjects even take in the visual images.  

The identity-protective impressions people form originate in a kind of biased sampling: by training their attention on the actor who they have the greatest stake in identifying as the wrongdoer, people are--without giving it a conscious thought, of course--prospecting in that portion of the visual landscape most likely to contain veins of data that fit their preconceptions.

Sadly, the benefit of gaining this remarkable insight into the workings of motivated cognition comes at the cost of intensified despair over the prospects for resolving societal conflicts over the appropriateness of the use of violent force by the police.

These disputes look like ones that could be resolved if we only had more information about the facts.  Hence the proposal that the police wear bodycams.

But this understanding has things backwards: the cultural conflict that this policy is meant to dispel will in fact shape what people see when they watch the bodycam videos.

Thus, the full value of the bodycam video policy—which I think can be considerable—will actually depend on our dispelling the antagonistic meanings that make police-citizen encounters a focal point for cultural conflict.

But in fact, that’s part of why I support the bodycam policy. 

The policy involves a significant commitment on the part of society to monitor police, and on the part of the police themselves to make their conduct amenable to monitoring.

Accepting that obligation itself conveys a signal, to the citizens who have the most reason to doubt it, that society and the police themselves are dedicated to assuring that the police will use force appropriately—to protect rather than violate the rights of the members of the community they serve.

More than this gesture will be needed, of course, to create the conditions of reciprocal cooperation and trust necessary to vanquish the distorting influence of cultural cognition on perceptions of violent confrontations between police and individual citizens.

But it’s a good start.


Granot, Y., Balcetis, E., Schneider, K. E., & Tyler, T. R. (2014). Justice is not blind: Visual attention exaggerates effects of group identification on legal punishment. Journal of Experimental Psychology: General, 143(6), 2196-2208. doi: 10.1037/a0037893 

Pennington, N., & Hastie, R. (1991). A Cognitive Theory of Juror Decision Making: The Story Model. Cardozo L. Rev., 13, 519-557.

Pennington, N., & Hastie, R. (1992). Explaining the Evidence: Tests of the Story Model for Juror Decision Making. Journal of Personality and Social Psychology, 62(2), 189-206.

Hastorf, A. H., & Cantril, H. (1954). They saw a game: A case study. The Journal of Abnormal and Social Psychology, 49(1), 129-134. doi: 10.1037/h0057880


"Anyone who doesn't agree must be a Marxist!" Plus "bans," "decibans," & Turing & Good on "evidentiary weight"

Maybe this (like the honeybadger) will turn out to be one of those discoveries on my part that everyone else already knows about, thereby revealing my disturbing remoteness from the zeitgeist, but the underscored sentence struck me as sooooooo hilarious I thought I should take the risk and share it, just in case it really is a hidden gem:

Actually, the paper (Good 1994) is not nearly so esoteric as it looks. Good was a brilliant writer, whose goal was to help curious people understand complicated things--as opposed to the sort of terrible writer whose goal is to be understood as brilliant by people he knows won't be able to comprehend what he is saying (which usually is nothing very interesting). 

I came across this paper while looking for accessible accounts of Turing's usage of "bans" and "decibans," a precursor of the Bayes factor, as a useful heuristic for making the concept of "weight of the evidence" tractable (in my case for a paper on the conceit that rules of evidence can be used to correct for foreseeable cognitive biases on the part of factfinders in legal proceedings).

A "ban," essentially, is a likelihood ratio of 10. That is, we would say that a piece of evidence has a weight of "1 ban" when it made some hypothesis 10x more probable (necessarily in relation to some other hypothesis) than we would have had reason to view it without that evidence.

Turing, in working on decryption at Blatchley Park in WW II, selected the ban as a unit to guide the mechanized search for solutions to codes generated by the German "Enigma" machine. Actually, Turing advocated using "decibans," which are 1/10 of ban, to assess the probative value of potential matches between sequences of code and plain text that poured out of the "bombe" decoders, electronic proto-computers that rifled through the zillions of combinations formed by the interacting Engima rotors, the settings of which determined the encryption "key" for Enigma-encrypted messages. 

Turing judged a deciban-- again, 1/10 of a "ban" or a likelihood ratio of 1.25:1 or 5:4 -- as pretty much the smallest difference in relative likelihood that a human being was likely to be able to perceive (Good 1979).

That's an empirical claim about cognition, of course.  What evidence did Turing have for it?  None, except the vast amount of experience that he and his fellow code-breakers were accumulating as they dedicated themselves to the task of productive deciphering of Enigma messages.  That certainly counts for something --but for how much? See the value of having units some system of "evidentiary weight" units here?

Good -- a 24-yr old, freshly minted Cambridge mathematician -- was part of Turing's team.

After the war, he wrote prolifically on probability theory, and Bayesian statistics in particular, for decades. He had lots of informative things to say about the concept of "evidentiary weight" (Good 1985).  He died in 2009.

Turns out he was really funny too.

Or at least I'd say that this sentence is at least 10 ban's worth of evidence that he was.


Good, I. (1985). Weight of evidence: A brief survey. In J. M. Bernardo, M. H. DeGroot, D. V. Lindley & A. F. M. Smith (Eds.), Bayesian statistics 2: Proceedings of the Second Valencia International Meeting (pp. 249-270). North-Holland: Elsevier.

Good, I. (1994). Causal Tendency, Necessitivity and Sufficientivity: an updated review Patrick Suppes: Scientific Philosopher (pp. 293-315): Springer.

Good, I. J. (1979). Studies in the history of probability and statistics. XXXVII AM Turing's statistical work in World War II. Biometrika, 66(2), 393-396. 



Good circa 1974 (at Va. Tech.)




Why expect people to *know* evolution? A question that deserves a good answer

Below is a thoughtful essay form Prajwal Kulkarni, a reflective physicist who is concerned about the societal controversy over teaching evolutionary science.  In it, he asks a question that I think deserves a good answer: why do we oblige citizens to learn evolution?

I am interested in the societal controversy over evolution, too.

As Praj notes, my main concern is with how to teach evolution effectively in a polluted science communication environment.  In particular, I am concerned that certain students—mainly secondary school ones but college ones too—will be deterred from understanding the modern synthesis by their apprehension that engaging the theory and evidence supporting it will betray their cultural identities.

Great research exists showing that it is possible to disentangle identity from knowledge in the pedagogy of evolution (by recognizing, e.g., the utter pointlessness of extracting professions of "belief" in what is being taught).  Good teachers know how to free curious students from the choice between knowing what’s known by science and being who they are as members of communities with diverse understandings of the meaning of life. 

Science educators ought to do that, I’m convinced, because in a liberal pluralistic society all individuals, regardless of their identity, are entitled to the opportunity to acquire the insights of science as a basic or primary good.  They ought to do it, too, because the state in a liberal pluralistic society is obliged not to condition access to primary goods on free citizens’ acceptance of a partisan moral or political orthodoxy.

But this account takes as a given that it is right to teach students the rudiments of evolutionary science.  Indeed, that it is right to expect them to learn it—just as it is right to expect them to learn to read or do math. 

Students who don’t learn to read or do math, or to reason well, will not only be disadvantaged but disadvantaged through the agency of the state, which certifies their low educational attainment.

Praj is asking, I think, why we make learning the rudiments of evolutionary science bear this consequence.  Why, in particular, when we know that understanding evolution, unlike being able to read and being able to do math, is bundled with identity-threatening cultural significance and, he believes, is not as essential for success in life as either of those or myriad other forms of knowledge.

I do in fact disagree—unequivocally—with Praj’s suggestion that we don’t “need” evolution, as he puts it.

That means, necessarily, that I think there is an answer to his question.

But the one I am inclined to give him is, by my own lights, simply not as good as it should be.  The problem with it, in my view, is not that it is “wrong” or missing some quality of analytical coherence or cogency.

It’s that it doesn’t give him, or at least those whom he speaks for, something they morally deserve: a satisfying account of why in fact it is justified to visit this particular obligation on them; an account that is satisfying, in particular, because it recognizes rather than evades the profound moral difficulty and complexity of the issue at hand.  

For it truly is the case, I believe, that when we oblige people to learn—oblige in the sense of making the consequence of failing to do so a stigma that indisputably and by design constrains their prospects in life—we are coercing them.  Coercing them, moreover, to do something that, even if we succeed in the form of disentanglement I favor in the teaching of evolution, will reasonably be understood by some of them (many fewer, I’m sure, if edcuators and others observe the disentanglement principle, but still some) as incompatible with being who they are.

So I think Praj deserves not only an answer but one of a particular sort.

An aporetic one: a response that, while unequivocal in its conclusion, openly acknowledges the ineradicable complexity of the question and resists effacing the same by resort to bluster and posturing, a style that betrays a regrettable defect of intellectual character.

I am convinced that it is indeed legitimate for the state to oblige citizens to learn evolutionary science. But being able to give an aporetic answer to Praj’s question is, in my view, a condition of the legitimacy of doing so, for only an aporetic response is capable of evincing on our part respect for the freedom and reason of the individual whom we are forcing to bear this restriction on liberty. 

What's the answer, then, to Praj's question? We should all be just as impelled as Praj to know what it is.

 --Dan M. Kahan

Why should everyone learn evolution?

Prajwal Kulkarni

Hello 14 billion readers of Cultural Cognition. I'm honored to be guest-blogging. This site is a big leap from my own blog, which has a paltry 7 billion readers. 

Today I'd like to expand on Dan's post from a few weeks ago: "What I believe about teaching "belief in" evolution and climate change." This passage in particular struck me: 

It makes me sad to think that some curious student might not get the benefit of knowing what is known to science about the natural history of our (and other) species because his or her teacher made the understandable mistake of tying that benefit to a gesture the only meaning of which for that student in that setting would be a renunciation of his or her identity.  

It makes me angry to think that some curious person might be denied the benefit of knowing what's known by science precisely because an "educator" or "science communicator" who does recognize that affirmation of "belief in" evolution signifies identity & not knowledge nevertheless feels that he or she is entitled to exactract this gesture of self-denigration as an appropriate fee for assisting someone else to learn. 

Such a stance is itself a form of sectarianism that is both illiberal and inimical to dissemination of scientific knowledge.

 I strongly agree with Dan on these points. But I'm going to take his last sentence one step further. Not only is it illiberal to insist students profess "belief in" evolution, it may be illiberal to force them to learn it in the first place. It's not obvious--to me at least--why learning evolution is mandatory. To see why, it might help to step back and look at science education more broadly. 

Imagine a world where the theory of evolution was not the lightning rod that it is. Even in that world, we could ask some general questions about science education and public science literacy: Who needs science education? What does it mean to be scientifically literate? Are there different definitions for scientists and non-scientists? 

While I’m not an expert, I have read a fair amount of the research on public understanding of science. Much of what I've read divides children into two groups: future scientists and engineers, and everyone else. Obviously these are not hard boundaries, and academics disagree if and where to draw lines. But it’s widely agreed that these groups are distinct and it’s tricky to balance both of their needs. Science literacy has a different meaning for physicists than for those in sales or marketing. 

So given that the overwhelming majority of students will not pursue careers in science and engineering, why should everyone be forced to learn natural selection if they’ll never use it after high-school? Before answering this question, it might be helpful to first reflect on what we want non-scientists to do with their scientific knowledge. What purposes do public science literacy serve?

You can spend a lifetime reading the scholarship on just this one question. My personal favorite is a 1975 article by astrophysicist Benjamin Shen. Shen outlines three categories of science literacy: practical, civic, and cultural. Science in the first category helps people in their daily lives, and includes topics like nutrition, health, and agriculture. The second would help people make informed civic decisions, while the third is in the same spirit as Shakespeare or Greek mythology.

To Shen’s categories I’ll add my own three-legged stool. Science education should leave non-scientists with some content knowledge (i.e. scientific facts), some understanding of scientific methods, and some sort of appreciation for and engagement with science. But I’m not sure specifically what content, how much process, and how to best cultivate appreciation. As far as I know, the experts aren’t sure either.

We’re now ready to return to evolution. Let’s adopt Shen’s framework, and remember that we’re focusing on non-scientists. I’ll repeat my question: why teach the theory of evolution in the first place? It has very little, if any, practical value. (Quick: when’s the last time you used the theory of evolution to help you decide anything?) It has almost no relevance to public policy. (Quick: when’s the last time the press covered the theory of evolution outside of creationism or intelligent design?) We’re left with the cultural value of evolution, admittedly a powerful justification.

Education is important for more than utilitarian reasons like economic growth. It helps promote civic virtues, patriotism, a sense of national identity, and a common culture (see Chapter 8 here). Science education can align with these goals.

But there are limits to how far we can push this argument, and cultural cohesion does not automatically trump individual rights. The landmark West Virginia v. Barnette, for example, declared that children cannot be forced salute the flag if doing so violates their–or their parents’–conscience. What if learning or believing evolution violates some parents’ conscience? Is there really a compelling state interest that everyone must learn it? If we grant exemptions to the Pledge of Allegiance, then why can't we grant exemptions to certain types of knowledge?

I would think educators and scientists would be open to different ways of teaching biology, especially since cultivating “scientific thinking” is often viewed as much more important than any specific content. It’s almost a truism: facts are less important than understanding the process of science and its ways of thinking. So if it’s scientific thinking we’re really after, why not spend an entire year studying human anatomy? Or maybe substitute evolution for a unit on bioengineering or a more in-depth look at organic chemistry. Unless the theory of evolution and nothing else in science teaches people to “think scientifically”, surely there are many ways to get there. A survey course in biology (what I and most people I know had) is not the only possible approach.

My goal in this post wasn't to convince you that evolution can safely be dropped from the science curriculum. I do hope, however, I've convinced you that there can be legitimate disagreement on whether it should be mandatory for all students. I do hope I've convinced you that there are tradeoffs--between freedom of conscience and public education, between science education for future scientists and non-scientists, and among different educational and pedagogical goals. I do hope I've convinced you that maybe there's much more to biology education than the theory of evolution.


Shen, Benjamin. Science literacy and the public understanding of science. Communication of Scientific Information, 44 – 52 (1975).


We need a CRT 2.0! And IRT should be used to develop it

I really really really like the Cognitive Reflection Test--or "CRT" (Frederick 2005).

The CRT is a compact three-item assessment of the disposition to rely on conscious, effortful, "System 2" reasoing as opposed to rapid, heuristic-driven "System 1" reasoning.  An objective or performance-based measure, CRT has been shown to be vastly superior to self-report measures like "need for cognition" ("agree or disagree-- 'thinking is not my idea of fun'; 'The notion of thinking abstractly is appealing to me' . . .") in predicting vulnerability to the various biases that reflect over-reliance on System 1 information processing  (Toplak, West & Stanovich 2011).

As far as I’m concerned, Shane Frederick deserves a Nobel Prize in economics for inventing this measure every bit as much Daniel Kahneman deserved his for systematizing knowledge of the sorts of reasoning deficits that CRT predicts.

Nevertheless, CRT is just not as useful for the study of cognition as it ought to be. 

The problem is not that the correct answers to its three items are too likely to be known at this point by M Turk workers—whose scores exceed those of MIT undergraduates (Chandler, Mueller & Paolacci 2014).

This is what CRT score distribution looks like when test is administered to normal people (i.e., not M Turk workers, ivy league college students, people who fill out surveys at on-line sites that solicit study subjects who want to learn their CRT scores, etc)Rather the problem is that CRT is just too darn hard when used to study legitimate study subjects.

The mean score when it is administered to a general population sample is about 0.65 correct responses (Kahan 2013; Weller, Dieckmann, Tusler, Mertz, Burns & Peters 2012; Campitelli & Labollita, 2010).

The median score is 0.

Accordingly, if we want to study how individual differences in System 1 vs. System 2 reasoning styles  interact with other dynamics—like motivated reasoning—or respond to interventions designed to improve engagement with technical information, then for half the population CRT necessarily gives us zero information.

Unless one makes the exceedingly implausible assumption that there's no variance to measure among this huge swath of people, this is a severe limitation on the value of the measure.

I've addressed this previously on this blog but I had occasion to underscore and elaborate on this point recently in correspondence with a friend who does outstanding work in the study of cognition and who (with good reason) is a big fan of CRT.

Here are some of the points I made:

I don’t doubt that CRT measures the disposition to use System 2 information processing more faithfully than, say, Numeracy [a scale that assesses proficiency in quantitative reasoning]. 

But the fact remains that Numeracy outperforms CRT in predicting exactly what CRT is supposed to predict—namely vulnerability to heuristic biases (Weller et al. 2012; Liberali 2012). Numeracy is getting a bigger piece of the latent disposition that CRT measures—and that's strong evidence of the need for a better CRT.

Or consider the Ordinary Science Intelligence assessment, “OSI_2.0,” the most recent version of a scale I've been working on to measure a disposition to recognize and give appropriate effect to scientific information relevant to ordinary, everyday decisions (Kahan 2014).  

Cognitive reflection is among the combination of reasoning proficiencies that this (unidimensional) disposition comprises.

But for sure, I didn't construct OSI_2.0 to be "CRT_2.0.”  I created it to help me & others do a better job in investigating how to asses the relationship between science comprehension and dynamics that constrain the effectiveness of public science communication.

With Item Response Theory, one can assess scale reliability continuously along the range of the underlying latent disposition (DeMars 2010).  Doing so for OSI_2.0, it can be seen that what CRT contributes to OSI_2.0’s measurement precision is concentrated at the very upper end of the range of the "ordinary science intelligence" aptitude:


This feature of CRT can be shown to make CRT less effective at what it is supposed to do—viz., predict individual differences in the disposition to resist over-reliance on heuristic processing.

The covariance problem is considered diagnostic of that sort of disposition (Stanovich 2009, 2011). Those vulnerable to over-reliance on heuristic processing tend to make snap judgments based on the relative magnitudes of the numbers in “cell A” and either “cell B” or “cell C” in a 2x2 contingency table or equivalent. Because they don't go to the trouble of comparing the ratio of A to B with the ratio of C to D, people draw faulty inferences about the significance of the information presented (Arkes & Harkness 1983).

As it should, CRT predicts resistance to this bias (Toplak, West & Stanovich 2011).

But not as well as OSI_2.0.


These are scatter plots of performance on the covariance problem (N = 400 or so) in relation to OSI_2.0 & CRT, respectively, w/ lowess regression plots superimposed.

The crook in  profile of the OSI_2.0 plot compared to the flat, boring profile of CRT shows that the former has superior discrimination (that is, identifies in a more fine-grained way how differences in reasoning ability affect the probability of getting the right answer).

Relatedly, the interspersing of the color-coded observations on the OSI_2.0 scatter plot shows how CRT is dividing people into groups that are both under- & over-inclusive w/r/t to proficiencies that OSI_2.0 is sorting out more reliably.

Or more concretely still, if I had only CRT, then I'd predict that  there is only a 40% probability that someone who is +1 on OSI_2.0-- just short of "1" on CRT -- would get the covariance problem correct, when in fact the probability such a person will get the right answer is about  60%. 

Similarly, if I used CRT to predict how someone at +1.5 on OSI_2.0 is likely to do on the problem, I'd predict about a 50% probability of him or her selecting the correct response -- when in fact the probability of a correct response for that person is closer to 75%.

Essentially, I'm going to be as satisfied with CRT as I am in OSI_2.0 only if  my interest is to predict performance of those who score either 2 or 3 on CRT -- the 90th percentile or above in a general population sample. 

But as can be seen from the OSI_2.0 scatter plot, it’s simply not the case that there’s no variance in people’s vulnerability to this particular heuristic bias in the rest of the population.  A measure that can't enable examination of how so substantial a fraction of the population thinks should really disappoint cognitive psychologists, assuming their goal is to study critical reasoning in human beings generally.

click on me-- your CRT score will instantly jump 2 points!Now, it's absolutely no surprise that OSI_2.0 dominates CRT in this regard: the CRT items are all members of  the OSI_2.0 scale, which comprises 18 items the covariance structure of which is consistent with measurement of a unidimensional latent disposition.  So of course it is going to be a more discerning measure of whatever it is CRT is itself measuring -- even if CRT_2.0 isn't faithfully measuring only that, as CRT presumably is. 

But that’s the point: we need a “better” CRT—one that is as tightly focused as the current version on the construct the scale is supposed to measure but that gets at least as big a piece of the underlying disposition as OSI_2.0, Numeracy or other scales that outperform CRT in predicting resistance to heuristic biases.

For that, "CRT 2.0" is going to need not only more items but items that add information to the scale in the middle and lower levels of the disposition that CRT is assessing.  IRT is much more suited for identifying such items than are the methods that those working on CRT scale development now seem to be employing.

I could certainly understand why a researcher might not want a scale with as many as 18 items. 

But again IRT can help here: use it to develop a longer, comprehensive battery of such items, ones that cover a large portion of the range of the relevant disposition.  Then administer an "adaptive testing" battery that uses strategically selected subsets of items to zero in on any individual test-taker’s location on the range of the measured “cognitive reflection” disposition (DeMars 2010).  Presumably, no one would need to answer From Mueller, Chandler, & Paolacci, Soc'y for P&SP, 1/28/12more than half dozen in order to enable a very precise measure of his or her proficiency -- assuming one has a good set of items in the adaptive testing battery.

Anyway, I just think it is obvious that researchers here can and should do better--and not just b/c MTurk workers have all learned at this point that the ball costs 5 cents!


Arkes, H.R. & Harkness, A.R. Estimates of Contingency Between Two Dichotomous Variables. J. Experimental Psychol. 112, 117-135 (1983).

Campitelli, G. & Gerrans, P. Does the cognitive reflection test measure cognitive reflection? A mathematical modeling approach. Memory & Cognition, 1-14 (2013).

Chandler, J., Mueller, P. & Paolacci, G. Nonnaïveté among Amazon Mechanical Turk workers: Consequences and solutions for behavioral researchers. Behavior research methods 46, 112-130 (2014).

DeMars, C. Item response theory (Oxford University Press, Oxford ; New York, 2010).

Frederick, S. Cognitive Reflection and Decision Making. Journal of Economic Perspectives 19, 25-42 (2005).

Kahan, D.M. Ideology, Motivated Reasoning, and Cognitive Reflection. Judgment and Decision Making 8, 407-424 (2013). 

Kahan, D.M. "Ordinary Science Intelligence: A Science Comprehension Measure for Use in the Study of Science Communication, with Notes on "Belief in" Evolution and Climate Change. CCP Working Paper No. 112 (2014).

Liberali, J.M., Reyna, V.F., Furlan, S., Stein, L.M. & Pardo, S.T. Individual Differences in Numeracy and Cognitive Reflection, with Implications for Biases and Fallacies in Probability Judgment. Journal of Behavioral Decision Making (2011).

Stanovich, K.E. Rationality and the reflective mind (Oxford University Press, New York, 2011).

Stanovich, K.E. What intelligence tests miss: the psychology of rational thought (Yale University Press, New Haven, 2009).

Toplak, M., West, R. & Stanovich, K. The Cognitive Reflection Test as a predictor of performance on heuristics-and-biases tasks. Memory & Cognition 39, 1275-1289 (2011).

Weller, J.A., Dieckmann, N.F., Tusler, M., Mertz, C., Burns, W.J. & Peters, E. Development and testing of an abbreviated numeracy scale: A Rasch analysis approach.