Spontaneous allocation of visual attention: dominant role of uniqueness.

Common sense suggests that unique or abruptly changing (transient) elements in a visual scene often draw attention involuntarily. Visual search studies paint a seemingly different picture, however Unique items usually draw attention involuntarily only when observers seek a unique target. One type of transient--abrupt onsets--draws attention involuntarily, but only when the observer is seeking an onset (Folk, Remington, & Johnston, 1992). One way of reconciling common-sense with these findings is to suppose that when people view a scene with no specific goal or task, they adopt a default set, which might prioritize novelty and/or transients. In two experiments, 336 subjects saw a single display of six items for 900 msec, expecting to have to describe it (Experiment 1) or make an aesthetic judgment about it (Experiment 2). One item in the display was either uniquely flashing (surrounded by static items) or uniquely static (surrounded by flashing items). In both studies, the unique item, even if static, was more often reported than the non-unique item, with flashing items enjoying an additional advantage.