When visual marking meets the attentional blink: More evidence for top-down, limited-capacity inhibition.

Abstract

An attentional blink (AB) paradigm was used to investigate the attentional resources necessary for visual marking. The results showed that distractors presented inside the AB cannot easily be ignored despite participants anticipating a future target display. This supports the hypothesis that attentional resources are required for visual marking. In addition, probe dots were better detected on blinked distractors than on successfully ignored distractors, but only when the task required new items to be prioritized. In a final experiment, a stronger negative carry-over effect on search occurred for targets identical to distractors presented outside rather than inside the AB. This suggests that at least part of the inhibitory processes involved in visual marking are nonspatial. The study of visual selective attention focuses on our visual system’s ability to prioritize certain visual events over others. In brief, efficient prioritization depends on the spatial and temporal properties of, as well as the task constraints surrounding, the visual event. In the present study, we considered the interactions between these spatial and temporal factors. Visual selective attention has a strong spatial component. Typically, visual objects relevant to our behavior ( targets) occupy limited spatial regions in a cluttered visual field filled with numerous irrelevant objects (distractors) that are simultaneously present. Sometimes selection of a target is quite effortless. For instance, Treisman and Gelade (1980) found that observers were very efficient in searching for a blue T in a display filled with brown Ts and green Xs. In this single-feature search task it is as if the unique feature (color) of the target guides selection. Typically, therefore, the number of distractors (the display size) has little or no effect on search reaction times (RTs), creating flat slopes for the Display Size RT search functions. In other tasks, selection may be more effortful. For example, Treisman and Gelade found that search for a green T among brown Ts and green Xs was much less efficient than a single-feature search. In this conjunction search, visual attention cannot be guided by the target because the target is defined only by a combination of features it shares with both distractor types. Instead, it is as if attention has to be shifted around the display in an effortful way until the target is found. Typically, therefore, conjunction-search RTs are dependent on the number of items simultaneously present, resulting in a relatively steep search slope (see Wolfe, 1994, and Wolfe, Cave, & Franzel, 1989; for variations; but see Duncan & Humphreys, 1989, for a different explanation).