Seeing the action: neuropsychological evidence for action-based effects on object selection.

Previous studies have shown that selection for perceptual report is often limited to one object at a time, with elements being selected together if they belong to part of the same perceptual group. Here we used the neuropsychological phenomenon of extinction in human patients with parietal lesions to show that selection is influenced also by action relations between objects. Performance was better for objects that were positioned spatially so that they could be used together, relative to objects that were positioned inappropriately for their combined use. The action relation was critical, as performance for pictures did not improve if the items were only verbally associated. We found the opposite result with words. Effects of action relations emerged even on trials where only one object could be reported, showing implicit coding of 'action' units for selection. The effects of verbal associations may instead reflect priming between lexical entries.