Abstract
Does sleep-dependent improvement on a visual search task depend on distractor inhibition or target enhancement? We investigated this question by testing two groups of subjects in three sessions across two days. Group N (Night first) was tested at 9PM on Day 1, and 9AM and 9PM on Day 2. Group D (Day first) was tested at 9AM and 9PM on Day 1, and 9AM on Day 2. Subjects detected targets that appeared alone, or embedded in a field of distractors, followed by a mask. Performance was measured as the exposure duration that led to 80% correct in a staircase procedure. We found that learning was demonstrated only after a night of sleep in both groups. Deterioration in performance occurred only in Group D across the first two daytime sessions, but not in Group N during the last two daytime sessions that followed a night of sleep. In some conditions, sleep-dependent improvement occurred for both the distractor present and distractor absent trials, while some conditions produced distractor-specific learning only. Our results suggest that improvement on these visual search tasks depends on inter-session sleep; that sleep may be a protective factor that prevents post-sleep deterioration; and that depending on the condition, sleep-dependent learning can modulate both target enhancement and distractor inhibition.
NIH RO1 EY12925, F32 EY015564