Abstract
When certain distractors (old items) appear before others (new items) during an inefficient visual search task, observers exclude the old items from the search if the target always appears as a new item (preview benefit). This effect is said to occur because of inhibitory visual marking (VM) for old objects in addition to attentional capture (AC) to new objects (Watson & Humphreys, 1997). However, another view claims that the preview benefit simply reflects AC (Donk & Theeuwes, 2001). To address the question of whether VM plays any role in addition to AC, we compared search performances for the target always appearing as a new item (“AC+VM”), for the target equally appearing as a new or old item (“AC”), and for the target among simultaneously presented items in a halved set size (“Half”). VM should not occur in the AC condition because there is no benefit in inhibiting old items. Furthermore, to standardize stimulus shape, we used letter stimuli made of parts of a digital symbol “8” (Yantis & Jonides, 1994) and orthogonally manipulated the shape changes in old distractors and the configuration of search items. No difference in slope was found among the conditions irrespective of changes in old items when items were arranged circularly, negating contribution from VM. In contrast, when items were presented at random positions within an invisible 7 x 7 matrix, the AC+VM condition’s slope was shallower than the AC condition’s, favoring the involvement of VM, and these slopes were higher than the Half condition’s irrespective of changes in old items. These findings suggest that 1) the effect of VM depends on the configuration of search items and 2) with complex displays, prioritizing selection for new objects is more effective if coupled with deprioritized selection for old objects.
Meeting abstract presented at VSS 2015