Why is there no negativity bias in evaluative conditioning? A cognitive-ecological answer.

Evaluative conditioning (EC) is the change of a conditioned stimulus's evaluation due to its pairing with an unconditioned stimulus (US). While learning typically shows negativity biases, we found no such biases in a reanalysis of meta-analytic EC data. We provide and test a cognitive-ecological answer for this lack of negativity bias. We assume that negativity effects follow from ecological differences in evaluative information's distributions (i.e., differential frequency). Accordingly, no negativity bias emerges because positive and negative information is equally frequent in most EC experiments. However, if negative (or positive) information is rare, we predict a negativity (positivity) bias. We tested this prediction in five preregistered experiments (three laboratory-based,