Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Neuroscience

Supervisor

Mohsenzadeh, Yalda

2nd Supervisor

Joanisse, Marc F.

Co-Supervisor

3rd Supervisor

Wang, Boyu

Co-Supervisor

Abstract

The attentional blink (AB) phenomenon refers to the failure to report the second target (T2) if it appears 200-500 ms after the first target (T1) in a stream of rapidly presented images. The present study aimed to investigate the neural representations of target processing under conditions where AB does or does not occur. We recorded EEG and behavioral data while participants viewed a rapid sequence of natural object images embedded with two face targets presented at two lag conditions: lag 3 (targets were 252 ms apart) and lag 7 (targets were 588 ms apart). Consistent with AB, our behavioral results showed a lower T2 identification accuracy in lag 3 compared to lag 7. We then used multivariate pattern analysis (MVPA) of EEG data to extract the neural dynamics of target processing over time. Comparing the neural representations of targets in the two lag conditions, we found that T1 processing coincided with T2 processing, resulting in suppressed T1 and T2 late representations in lag 3, where AB happened, but not in lag 7, where there was enough time between the two targets. Our results also indicated that target representations were different between participants with a strong AB effect (blinkers) and those with a weak AB effect (non-blinkers). These findings carry significant implications for theories of attentional blink, highlighting the need for their extension in order to account for naturalistic paradigms and new findings.

Summary for Lay Audience

In this study, we investigated a fascinating phenomenon called the attentional blink (AB), which occurs when people are unable to correctly identify a second target image (T2) in a rapid sequential presentation of images if it appears shortly after the first target image (T1). The objective of this study was to explore and compare how our brain processes targets during AB. To achieve this, we measured brain activity and collected behavioral data from participants while they observed a rapid sequence of object images containing two face targets. T2 was presented either with a short delay (lag 3: T2 is item 3 after T1) or a longer delay (lag 7: T2 is item 7 after T1) after T1.

Consistent with previous findings, we discovered that participants had lower accuracy in identifying T2 when it appeared shortly after T1 (lag 3) compared to when there was more time between them (lag 7). To better understand the underlying neural dynamics of the attentional blink, we employed a technique called multivariate pattern analysis on the brain data. This analysis allowed us to examine how the representations of target processing in the brain evolved over time. By comparing the neural representations of T1 and T2 in the two lag conditions, we observed that T1 processing interfered with T2 processing, leading to diminished late representations of both targets in the lag 3 condition, where AB occurred. In contrast, in the lag 7 condition, where there was a greater temporal gap between the targets, this interference was not observed, and the representations of both targets were relatively preserved. These findings challenge current theories of attentional blink, as they cannot be easily explained by existing models.

Overall, this study provides valuable insights into how our brains process multiple targets in rapid succession, shedding light on the attentional blink phenomenon. Understanding these mechanisms can enhance our understanding of how the human brain perceives the ever-changing visual world around us.

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