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Objects and events in the attentional blink
Sheppard, D.M., DUNCAN, J., Shapiro, K.L. & Hillstrom, A.P.
Psychological Science, 13(5), 410-415
Year of publication:
When two visual targets, T1 and T2, are presented in rapid succession, detection or identification of T2 is almost universally degraded by the requirement to attend to T1 (the "attentional blink" or AB). As described by Shapiro et al. (1994), one interesting exception occurs when T1 is a brief gap in a continuous letter stream, and the task is to discriminate its duration. One hypothesis is that an AB is only triggered by attention to a patterned object. Eliminating this, we show that duration judgments produce no AB whether the judged duration concerns a short gap in the letter stream (Experiment 1), or a letter presented for slightly longer than others (Experiment 2). Experiment 3 goes on to show that when identification of an identical ëlonger letter T1í is required, the AB is re-established. Direct perceptual judgments of letter streams with gaps embedded show that while brief gaps result in the percept of a single, briefly hesitating stream, longer gaps result in the percept of two separate streams with a separating pause. Correspondingly, an AB is produced in Experiment 4 when participants are required to judge the duration of longer T1 gaps. We propose that, like spatially separated objects, temporal events are parsed into discrete, hierarchically-organized events;. An AB is triggered only when a new attended event is defined, either when a long pause creates a new perceived stream (Experiment 4), or when attention shifts from stream to letter levels (Experiment 3).