A study was conducted by Dan Kahan of Yale University and three colleagues
involving a demographically representative sample of 1111 American
adults recruited by Polimetrix/YouGov, an online survey research
firm. Preliminary questions were used to categorize the participants
along two dimensions:
- Liberalism v. Conservatism: They rated themselves as very liberal to very conservative on a 5-point scale, and strong Democrat to strong Republican on a 7-point scale. These scales were combined, and the participants were divided at the midpoint into liberal Democrats and conservative Republicans.
- Numeracy: Participants' numeracy was measured using nine real world mathematical problems. They received a numeracy score of 0 to 9.
Each participant
was then asked to answer one of the four judgment of contingency
problems shown in Table 2 of Part 1. These are labeled by the
correct answer to the problem:
- Rash increases: The rash got worse when the skin cream was used.
- Rash decreases: The rash got better when the skin cream was used.
- Crime increases: There was more crime with the ban on concealed weapons.
- Crime decreases: The ban on concealed weapons reduced crime.
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| Table 3 |
The top graph presents the results for the skin cream questions. On the vertical
dimension, the higher the line, the more people answered the question
correctly. Horizontally, as you go from left to right, numeracy
increases. The four groups all show almost the same results. As you
would expect with content-neutral problems, as numeracy increases,
more people answer correctly.
The bottom graph shows the results for the gun control questions. There is a tendency
for scores to improve with numeracy, but the results are not uniform.
The most striking trend is evidence of confirmatory bias.
Participants are more likely to give the correct answer in the two
conditions where it is consistent with their political views—the
liberals when crime decreases and the conservatives when crime
increases. When the correct conclusion is inconsistent with the
participant's partisan ideology, the lines are almost flat, which
means that the high numeracy people are not successfully
correcting their biases. The numerate liberals claim that gun
control is effective, even when the evidence shows it is not. The
numerate conservatives claim that concealed weapons discourage crime,
even when the evidence shows they do not. These labels may help to
make the graph more clear.
 |
| Table 4 |
What is going on in
the minds of these participants? It's likely that participants in
all four groups initially engage in System 1 thinking. They look at
the data and immediately believe what their political ideology leads
them to expect. For the two groups in which the data are consistent
with their prior beliefs, this is no problem. If they use System 2
to do the math, they will become more confident of the correct
conclusion. But the two groups in which the data are inconsistent
with their prior beliefs are faced with a conflict if they engage in
System 2 thought. The results suggest that either they don't bother,
or if they do, they manage to reinterpret the data in a way that
confirms their expectations.
These
data support the identity-protective cognition thesis
rather than the science-comprehension thesis.
It seems unlikely that additional math and science training would
help these folks to draw the correct conclusion when that conclusion
conflicts with their ideology. One commentator referred to these results as “the most depressing discovery about the brain, ever.”
(Journalists have a depressing tendency to refer to the results of
psychological research as discoveries about “the brain,” falsely implying that they are physiologically determined. I would say these
results demonstrate the effectiveness of political socialization.)
They are consistent with findings showing that giving people information which corrects common misconceptions sometimes backfires
and causes them to believe them more strongly. It also supplements
Kahan's previous finding that the most scientifically literate Americans are not more
convinced that climate change is a serious threat, but are more
ideologically polarized than those who are less scientifically
literate.
Despite the fact
that the authors proposed that such results would raise doubts about
the possibility of rational self-government, they do not recommend that we curtail participatory democracy and turn over our more
important decisions to Big Brother. Kahan sees the problem as a
failure of scientific communication. He proposes that scientific
issues be reframed so as to reaffirm the ideological beliefs of those
who might otherwise be skeptical. For example, in another article he suggests that global warming be reframed as a technical problem to be
address by corporations rather than a political problem to be
addressed by government:
They [conservatives] would probably look at the evidence more
favorably, however, if made aware that possible responses to climate
change include nuclear power and geoengineering. . . Similarily,
[liberals] are less likely to reflexively dismiss the safety of
nanotechnology if they are made aware of the part that nanotechnology
might play in environmental protection, and not just its usefulness
in the manufacture of consumer goods.
Here is a video of
Kahan discussing the results of his global warming studies and his
suggestions for improving scientific communication.
Kahan seems to be
suggesting that our ideological disagreements can be solved through
clever marketing, but this seems an unlikely solution. For example,
any serious attempt to curtail climate change through either nuclear
power or geoengineering would encounter strong and well-founded
objections from important members of the scientific community, and
consensus would quickly disappear.
Before we throw up
our hands in despair, Kahan's results need to be replicated with a
broader range of issues. However, to be fair, global warming is such
an important issue that failure to reach consensus on a solution will
make all the other issues which we think we care about seem like the
equivalent of rearranging the deck chairs on the Titanic.
However, there are
some research findings that seem to offer greater hope of overcoming
ideological polarization. I will discuss them in future posts. But
first, for those that are interested, an appendix about the differences between liberals and conservatives.
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