An Electrophysiological Investigation of Early Evoked Responses to Visual Onsets During the Attentional Blink

Bianca Hart (2010). An Electrophysiological Investigation of Early Evoked Responses to Visual Onsets During the Attentional Blink Honours Thesis, School of Psychology, The University of Queensland.

       
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Author Bianca Hart
Thesis Title An Electrophysiological Investigation of Early Evoked Responses to Visual Onsets During the Attentional Blink
School, Centre or Institute School of Psychology
Institution The University of Queensland
Publication date 2010
Thesis type Honours Thesis
Supervisor Mattingley, Jason
Total pages 79
Abstract/Summary Mechanisms of attention serve to prioritise stimuli that are currently relevant for ongoing behaviour and biological needs. Conscious perception is thus limited by the extent to which attention selects sensory input for further processing. When observers monitor a rapid sequence of visual stimuli at fixation, their ability to detect a second target stimulus is often impaired if it appears within 500ms of an earlier target event, a phenomenon termed the attentional blink (AB). The aim of the current study was to examine the neural correlates of this decrement in target detection during rapid serial visual presentation. Thirty-one participants monitored an RSVP stream at fixation while neural event-related potentials were measured using a 64-channel electroencephalographic system. The task involved twoalternative, forced-choice judgments on an initial target stimulus (T1) and a subsequent target (T2), with the latter occurring at one of three temporal lags (100, 200, and 700ms). On 50% of T2 displays a small, task-irrelevant grating was presented in the upper-right quadrant, the purpose of which was to elicit a visual response from the left primary visual cortex (the C1 component). Participants showed a reliable AB at the 200ms lag relative to the 100 and 700ms lags. This was mirrored by a significant change in the mean amplitude of the N200 component for the 200ms lag. In contrast, there was no lag-specific change in the early C1 component. These results suggest that the AB reflects a neural bottleneck in information processing that arises only after early sensory registration within the primary visual cortex.

 
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Created: Tue, 05 Apr 2011, 11:46:22 EST by Lucy O'Brien on behalf of School of Psychology