Abstract:
When people evaluate claims they often rely on what comedian Stephen
Colbert calls truthiness, judging claims using subjective feelings of truth, rather
than drawing on facts. Over seven experiments I examined how nonprobative
photos can manufacture truthiness in just a few seconds. I found that a quick
exposure to a photo that relates to, but does not provide any probative evidence
about the accuracy of claims can systematically bias people to conclude claims are
true. In Experiments 1A and 1B, people saw familiar and unfamiliar celebrity
names and, for each, quickly responded "true" or "false" to the claim "This
famous person is alive" or (between subjects) "This famous person is dead." Within
subjects, some names appeared with a photo of the celebrity engaged in his/her
profession whereas other names appeared alone. For unfamiliar celebrity names,
photos increased the likelihood that subjects judged the claim to be true.
Moreover, the same photos inflated the truth of "Alive" and "Dead" claims,
suggesting that photos did not produce an "alive bias," but a "truth bias."
Experiment 2 showed that photos and verbal information similarly inflated
truthiness, suggesting that the effect is not peculiar to photographs per se.
Experiment 3 demonstrated that nonprobative photos can also enhance the
truthiness of general knowledge claims (Giraffes are the only mammals that cannot jump).
In Experiments 4-6 I examined boundary conditions for truthiness. I found that
the semantic relationship between the photo and claim mattered. Experiment 4
showed that in a within-subject design, related photos produced truthiness, but
unrelated photos acted just like the no photo condition. But unrelated photos were
not always benign, Experiment 5 showed that their effects depended on
experimental context. In a mixed design, related photos produced truthiness and
unrelated photos produced falsiness.
Although the effect of related photos was robust across materials and variation
in experimental context, when I used a fully between-subjects design in
Experiment 6, the effect of photos (related and unrelated) was eliminated. These
effects add to a growing literature on how nonprobative information can
influence people’s decisions and suggest that nonprobative photographs do more
than simply decorate, they can rapidly manufacture feelings of truth. As with
many effects in the cognitive psychology literature, the photo-truthiness effect
depends on the way in which people process and interpret photos when evaluating
the truth of claims.
