Attentional blink

Attentional blink (AB) is a phenomenon that reflects the temporal costs in the allocating selective attention. The AB is typically measured by using rapid serial visual presentation (RSVP) tasks, where participants often fail to detect a second salient target occurring in succession if it is presented between 180-450 ms after the first one. Also, the AB has been observed using two backward-masked targets and auditory stimuli. The term attentional blink was first used in 1992, although the phenomenon was probably known before.

The precise adaptive significance behind the attentional blink is unknown, but it is thought to be a product of a two-stage visual processing system attempting to allocate episodic context to targets. In this two-stage system, all stimuli are processed to some extent by an initial parallel stage, and only salient ones are selected for in-depth processing, in order to make optimum use of limited resources at a late serial stage.

One curious aspect of attentional blink is that it usually includes "lag 1 sparing", meaning that targets presented very close together in time (at "lag 1" or consecutively in the RSVP stream) are not affected by the attentional blink, even though items presented at slightly greater lags are significantly impaired. In attentional blink, participants in experiments have trouble reporting multiple targets that are in succession to one another, and will only report one accurately when these targets are presented to them 200ms to 500ms apart according to a study by Visser et. al (2015) . These targets are denoted as T1, T2, etc. The phenomena lag-1 sparing refers to the performance of T2 as opposed to what precedes it, T1. T2 performance was originally hypothesized to be reported far less often and less accurately by participants than T1, because the attention of the participant would still be on T1 while T2 was presented immediately afterwards. Visser also thought that the participants would be too focussed on finding the first target that they would miss the second target completely. However, participants actually did better identifying T2 than they were at identifying T1 when the targets were separated by one or two distractors, denoted also as lags.

A possible explanation for lag-1 sparing is that this phenomena is heavily interconnected with attentional blink, but does not operate on the same cognitive mechanisms and requires different stimuli to occur. Specifically, for lag-1 sparing to occur, it needs visual input as practice targets. These targets can be numbers or letters presented in rapid succession. When the first target, T1, is presented, it creates an attentional window because of its novelty, meaning that it attracts and holds more attention by the participant. The novelty that wears off between T1 and T2 creates a “boost” in attention and opens a metaphorical window for faster cognition. Participants now know what and how to look for targets, so they find targets more quickly. This attentional widow remains open long enough for T2 to be presented and processed at a much higher rate because of shared characteristics to T1. Targets are normally presented in less than .5 of a second from each other. Lag-1 sparing also occurred regardless of how information was visually presented. Of two RSVP streams— where T1 location was known in the first stream and unknown in the second stream, lag-1 sparing occurred whether T2 was in the same stream as T1, or in a different stream than T1.

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