Attentional capture effects are modulated by the number of concurrently maintained search goals

Introduction In hybrid visual-memory search, multiple search goals are concurrently maintained in memory and searched for in a visual display. When there are few goals, maintenance can operate in visual working memory, whereas when there are many concurrent search goals, they may be maintained in activated long-term memory. A central question here is how multiple search goals are concurrently maintained in memory and selectively enhanced during search. Two attentional capture effects illustrate goal enhancement in the presence of distraction: contingent capture, when distractors resemble the current trial's target, and set-specific capture, when distractors resemble one of your search goals, but not the current trial's target. Methods In the present study, participants memorized sets of 2, 4, or 16 objects, and searched for them in a continuous rapid serial visual presentation stream. On critical trials, a goal-related distractor appeared 1–2 frames before the target, matching either the same category as that trial's target (contingent capture) or a different target category than that trial's target (set-specific capture). Results Contingent capture was greatest with 16-item sets, whereas set-specific capture was greatest with 2-item sets, and 4-item sets were in between. Discussion These findings indicate that search goal enhancement flexibly adapts to memory load, with implications for models of goal maintenance and attentional control. They also provide the first evidence of set-specific capture with complex objects as search goals.