Valence, Not Utility, Underlies Reward-Driven Prioritization in Human Vision

Objects associated with reward draw attention and evoke enhanced activity in visual cortex. What is the underlying mechanism? One possibility is that reward's impact on vision is mediated by unique circuitry that modulates sensory processing, selectively increasing the salience of reward-associated stimuli. Alternatively, effects of reward may be part of a more general mechanism that prioritizes the processing of any beneficial object, importantly including stimuli that are associated with the evasion of loss. Here, we test these competing hypotheses by having male and female humans detect naturalistic objects associated with monetary reward, the evasion of equivalent loss, or neither of these. If vision is economically normative, processing of objects associated with reward and evasion of loss should be prioritized relative to neutral stimuli. Results from fMRI and behavioral experiments show that this is not the case: whereas objects associated with reward were better detected and represented in ventral visual cortex, detection and representation of stimuli associated with the evasion of loss were degraded. Representations in parietal cortex reveal a notable exception to this pattern, showing enhanced encoding of both reward- and loss-associated stimuli. Experience-driven visual prioritization can thus be economically irrational, driven by valence rather than objective utility.

SIGNIFICANCE STATEMENT Normative economic models propose that gain should have the same value as evasion of equivalent loss. Is human vision rational in this way? Objects associated with reward draw attention and are well represented in visual cortex. This is thought to have evolutionary origins, highlighting objects likely to provide benefit in the future. But benefit can be conferred not only through gain, but also through evasion of loss. Here we demonstrate that the visual system prioritizes real-world objects presented in images of natural scenes only when these objects have been associated with reward, not when they have provided the opportunity to evade financial loss. Visual selection is thus non-normative and economically irrational, driven by valence rather than objective utility.