Itsy bitsy spider?: Valence and self-relevance predict size estimation

Abstract

The current study explored the role of valence and self-relevance in size estimation of neutral and aversive animals. In Experiment 1, participants who were highly fearful of spiders and participants with low fear of spiders rated the size and unpleasantness of spiders and other neutral animals (birds and butterflies). We found that although individuals with both high and low fear of spiders rated spiders as highly unpleasant, only the highly fearful participants rated spiders as larger than butterflies. Experiment 2 included additional pictures of wasps (not self-relevant, but unpleasant) and beetles. The results of this experiment replicated those of Experiment 1 and showed a similar bias in size estimation for beetles, but not for wasps. Mediation analysis revealed that in the high-fear group both relevance and valence influenced perceived size, whereas in the low-fear group only valence affected perceived size. These findings suggest that the effect of highly relevant stimuli on size perception is both direct and mediated by valence.

Keywords: Individual differences; Phobia; Self-relevance; Size estimation; Spiders.

Fig. 1

Stimuli and procedure—Experiment 1. (A) Stimuli pictures—all stimuli were presented in the same physical size of 228 × 197 pixels. (B) An example of a typical trial. The same pictures of a fly and lamb appeared in every trial with the stimulus to-be-rated appearing in a random position underneath. (C) Visual analog scale (VAS): the left side of the line equals 0%, representing small conceptual size (closer to a fly) or low unpleasantness rating; the right side of the line equals 100%, representing large conceptual size (closer to a lamb) or high unpleasantness. Note, the pictures presented here are for illustration purposes. Pictures of spiders were taken from the IAPS (International Affective Picture System; Lang, Bradley, & Cuthbert, 2008) while pictures of the other animals were taken from “google images”. These pictures were labeled for reuse under “usage rights”.

Fig. 2

Results—Experiment 1. (A) Size (0 = the size of a fly, 100 = the size of a lamb), and (B) unpleasantness (0 = “not at all”, 100 = “very unpleasant”) estimations by group and condition.

Fig. 3

Stimuli and procedure—Experiment 2. (A) Stimuli pictures included wasps and beetles (depicted here), and also spiders and butterflies from Experiment 1. (B) An example of a typical trial. The same pictures of a fly and a rabbit appeared in every trial with the stimulus to be rated appearing in a random position underneath.

Fig. 4

Results—Experiment 2. (A) Size (0 = the size of a fly, 100 = the size of a rabbit), and (B) unpleasantness (0 = “not at all”, 100 = “very unpleasant”) estimations by group and condition.

Fig. 5

Mediation model for the relationship between relevance, valance (unpleasantness) and spider size in the high-fear group. B = direct effect; B′ = indirect effect.