Academic journal article Attention, Perception and Psychophysics

Temporal Tuning and Attentional Gating: Two Distinct Attentional Mechanisms on the Perception of Rapid Serial Visual Events

Academic journal article Attention, Perception and Psychophysics

Temporal Tuning and Attentional Gating: Two Distinct Attentional Mechanisms on the Perception of Rapid Serial Visual Events

Article excerpt

We examined the relationship between two different attention limitations on the perception of rapid events: the attentional awakening (AA, an inability to successfully process a target when it appears early on in a rapid stream of events) and the attentional blink (AB, an inability to successfully process a second target when it appears shortly after a first target [T1]). In four experiments, we failed to find a relationship between the magnitudes of these phenomena. Furthermore, we found two manipulations that selectively modulated the magnitude of each effect without altering the magnitude of the second effect: Expected range of possible rapid serial visual presentation lengths modulated the AA (but not the AB), suggesting that the AA reflects an attentional setup cost for perceiving a protracted series of rapid events, whereas the number of possible T1 positions in the stream modulated the magnitude of the AB (but not the magnitude of the AA). Our results suggest that, despite the surface similarities between the two phenomena, different mechanisms are responsible for these two attentional limitations: Whereas the AA reflects a starting cost associated with the time required to temporally tune attention to the stimulus stream, the AB reflects a blocking of undesired stimuli, aimed at protecting consolidation of T1 processing.

Much research has examined the scope of our ability to select stimuli from our environment for higher level processing. One common approach to uncovering the mechanisms responsible for our ability to selectively attend to various elements of our environment is to examine instances in which our attentional mechanisms fail or perform suboptimally. By determining why and when we go astray, we are able to shed light on how our attentional system manages to extract relevant information from the detailed and complex environment we inhabit. One such investigation of attentional failures looks into how well one can identify two targets (T1 and T2) presented in a stream of distractors, close in time, and at the same location in space. During these rapid serial visual presentation (RSVP) tasks, it is commonly found that identification of T2 is impaired if it is presented near in time to the first target (Raymond, Shapiro, & Arnell, 1992). This impairment is strongest at around 200 msec after the presentation of T1 and gradually recovers until baseline identification performance is reached around 500 msec after T1 (a schematic of this finding can be seen in Figure 1). This decrease and recovery of identification accuracy is known as the attentional blink (AB).

There exist two classes of theories regarding the mechanisms responsible for the AB. The deficit in processing T2 soon after T1 is thought to result from either (1) a reduction in available processing resources for identifying T2 (bottleneck models) or (2) a perceptual filter that blocks processing of T2 altogether ( filter models). A classic theory of the AB proposed by Chun and Potter (1995) is a two-stage model that argues for limitations in central encoding. Whereas we can perceptually process a vast amount of visual information at any given time, the ensuing representations are short-lived and brittle. In order to protect such representations from decay and from masking by subsequent stimuli, we must protect them by encoding them into short-term memory. The argument is that this transfer from perception to memory (i.e., central encoding) cannot deal with more than one target stimulus at a time (see also Giesbrecht & Di Lollo, 1998; Jolicoeur & Dell'Acqua, 1998). Within this framework, the AB pattern occurs because of a bottleneck in central encoding; if central encoding is busy processing T1, T2's perceptual representation cannot be encoded into memory before it is masked by subsequent stimuli. Recent work by Dux and colleagues (Dux, Asplund, & Marois, 2008, 2009; Dux, Ivanoff, Asplund, & Marois, 2006) has continued to provide evidence in favor of resource depletion accounts of the AB. …

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