Nonprobative photos inflate the truthiness and falsiness of claims

Newman, E. J. (2013). Nonprobative Photos Inflate the Truthiness and Falsiness of Claims. Open Access Te Herenga Waka-Victoria University of Wellington. Thesis. https://doi.org/10.26686/wgtn.17003764.v1

Abstract de l'autrice

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.

Chapter 1

In this thesis I use the term “truthiness” to refer to a category of phenomena in which the addition of nonprobative information causes people to shift rapidly towards believing a claim (see also the illusory truth effect; Begg, Anas, & Farinacci, 1992).

Overview

If photos help boost cognitive availability of related thoughts and images, or help people trawl for and selectively interpret information in line with their hypothesis about unfamiliar celebrities, then photos should increase the truthiness of claims about those celebrities, regardless of whether the claim is that the celebrity is alive or dead (cf. Unkelbach, 2007).

Chapter 2

Experiment 1A and 1B

Design:

• VI1: photograph: yes, no
• VI2: familiarity: familiar, unfamiliar (i.e. est-ce que la personne est "connue" ou non)
• VI3: claim: alive, dead
• VD: C score (déviation à dire "true")

Résultant en un 2x2x2 mixed design, avec photograph et familiarity within subjects et le claim between subjects.

Résultats:

• Elle a réalisé une mixed repeated measures (photograph) x 2 (familiarity) x 2 (claim) ANOVA
• Effet de la photo:
  • Experiment 1A, F(1, 90) = 4.87, p = .03, η_p² = .05;
  • Experiment 1B, F(1, 46) = 10.53, p < .01, η_p² = .19)

Bias for claims about familiar and unfamiliar names (in Experiments 1a-1b) presented with or without a photograph and collapsed across dead/alive factor. Negative value of c is a bias to say true. In Experiments 1a-2, photos (or words) affected bias for unfamiliar names. Error bars show 95% within-subject confidence intervals for the photo/no-photo effect at each level of familiarity/difficulty (see Masson & Loftus, 2003)

Discussion Newman remarque que les gens ont tendance à trouver vraies les "Alive" claims plus souvent que les "Dead" claims.

A ce moment, Newman se demande si c'est un biais de truthiness ou d'aliveness (i.e. le fait qu'on voit la photo fait penser que la personne est en vie).

Photos might promote truthiness because they provide a rich semantic context that facilitates the generation of thoughts and images relating to the claim. But these results also fit with the idea that feelings of truthiness arose because photos are inherently credible or that over time people have come to associate photos with the conclusion that something is real and true (cf. Unkelbach, 2007).