Desirability biases perceptual decisions in the aversive domain

Perceptual judgments are often influenced by goals and preferences, resulting in biased judgments that deviate from objective reality. When presented with ambiguous images, observers are biased to report seeing images associated with rewards. However, it remains unclear whether this is driven by a bias toward stimuli that are desirable or stimuli that are motivationally salient. As rewards are both desirable and motivationally salient, these effects are not easily dissociated in a reward context. This study investigates the effects of desirability and motivational salience on perceptual judgments in an aversive context involving financial losses. Across two experiments conducted between 2023 and 2024, participants completed a visual categorization task where ambiguous stimuli were associated with a large financial loss. Participants' perceptual judgments were biased away from stimuli associated with the loss, indicating a desirability bias. Drift diffusion model analyses revealed that this bias was due to a shift in the starting point of evidence accumulation, such that participants required more evidence to commit to a response associated with an undesirable outcome. The bias in starting point correlated with individual differences in punishment sensitivity but not reward sensitivity, highlighting how individual traits shape motivational effects on perceptual decisions. Results replicated across an in-lab sample and a larger online sample. Altogether, our study provides robust evidence of a desirability bias in perceptual decisions involving financial losses, identifying both the computational mechanisms and trait-level differences that influence how people decide what they see when faced with the prospect of undesirable outcomes. (PsycInfo Database Record (c) 2025 APA, all rights reserved).