Experience enhances texture saliency by reducing behavioural and cortical responses to irrelevant texture features

Abstract

It is well known that experience increases saliency of attended orientation in texture segmentation. We asked whether experience modulates the saliency of unattended orientation when conflicting with that being explicitly attended. Observers viewed a texture bar, either parallel or orthogonal to its elements, which segmented from background on the bases of a fixed orientation contrast. Two groups of subjects were asked to discriminate the orientation of either the global bar or local elements. Psychophysical data show that in the first block of trials both global and local orientation discrimination are impaired by the conflicting implicit orientation in orthogonal bar. However, experience improves discrimination more for orthogonal bar which becomes, in the last sessions, as salient as the parallel one. The novel finding is that experience has the effect of reducing VEPs amplitude, but only when conflicting orientation is interfering with the task as in orthogonal bar. Our behavioural and neurophysiological data, besides confirming that experience increases saliency of explicitly attended orientation, they provide a novel evidence that implicitly perceived orientation (either to global or local orientation) is inhibited by experience when it interferes with orientation that subjects are explicitly required to attend.