Unconscious, transient binding by time: Neuropsychological evidence from anti-extinction
Glyn W. Humphreys, M. Jane Riddoch, Gudrun Nys, Dietmar Heinke
Anti-extinction occurs when there is poor report of a single stimulus presented on the contralesional side of space, but better report of the same item when it occurs concurrently with a stimulus on the ipsilesional side (Goodrich & Ward, 1997). We report a series of experiments that examine the factors that lead to anti-extinction in a patient GK, who has bilateral parietal lesions but more impaired identification of left-side stimuli. We show a pattern of anti-extinction when stimuli are briefly presented, which is followed by an extinction effect when stimuli are left for longer in the visual field. In Experiments 1 and 2 we present evidence that the anti-extinction effects are defined by offsets. In Experiments 3 and 4 we report that performance is not strongly affected by whether the same of different tasks are performed on the ipsi- and contralesional stimuli, and the anti-extinction effect also survives trials where eye movements are made to right-side stimuli. Experiment 5 provides evidence that anti-extinction is due to temporal grouping between stimuli, rather than cueing attention to the contralesional side. Experiment 6 demonstrates that anti-extinction dissociates from GK's conscious perception of when contra- and ipsilesional stimuli occur together. We interpret the data as indacting that there is unconscious and transient temporal binding in vision.
Cognitive Neuropsychology, 19(4):361-380, 2002.