Non-probative photos (or words) inflate truthiness

When people evaluate claims, they often rely on what comedian Stephen Colbert calls 'truthiness,' or subjective feelings of truth. In four experiments, we examined the impact of nonprobative information on truthiness. In Experiments 1A and 1B, people saw familiar and unfamiliar celebrity names and, for each, quickly responded 'true' or 'false' to the (between-subjects) claim 'This famous person is alive' or 'This famous person is dead.' Within subjects, some of the names appeared with a photo of the celebrity engaged in his or her profession, whereas other names appeared alone. For unfamiliar celebrity names, photos increased the likelihood that the subjects would judge the claim to be true. Moreover, the same photos inflated the subjective truth of both the 'alive' and 'dead' claims, suggesting that photos did not produce an 'alive bias' but rather 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 (e.g., Giraffes are the only mammals that cannot jump). These effects add to a growing literature on how nonprobative information can inflate subjective feelings of truth.