Abstract
Temporal context or adaptation, the preceding seconds to minutes of stimulus history, profoundly affects visual perception. Despite the robustness and ubiquity of these effects, their functional role in perception and cortical processing in many cases remains unclear. In contrast, the effects of spatial context and their role in perception are better understood: spatial contextual effects highlight features that differ from those in surrounding regions, determining salience and giving rise to ‘pop-out’. Similarities in the perceptual and neural effects of spatial and temporal context raise the possibility that they may serve similar functions. We therefore tested the possibility that adaptation serves to enhance the salience of features differing from their temporal context. We measured the effects of prolonged (40 s) adaptation to a counterphase grating on performance in a classical search task. Subjects searched for a target whose orientation was offset by 10 - 90° relative to distracters. Distracters were oriented either parallel or orthogonal to the adapter. We find that adaptation reduces both reaction times and the number of saccades made to find targets with small orientation offsets, suggesting that adaptation can enhance the salience of such targets. By extending existing models of salience to include the effects of adaptation, we illustrate how stimulus-specific adaptation and center-surround antagonism in early visual pathways could give rise to such effects. Our results provide evidence of a beneficial effect of adaptation on perception, and suggest a new view of the role of adaptation in perception and cortical processing.
Meeting abstract presented at VSS 2012