An Exploration of the Effects of Low Target Prevalence on Attention to Subsequent Visual Events

Bailey, Georgina (2026) An Exploration of the Effects of Low Target Prevalence on Attention to Subsequent Visual Events. Doctoral thesis, Liverpool Hope University.

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Abstract

The thesis investigates how target prevalence in a primary visual task affects attentional engagement in a temporally proximate secondary task through behavioural and electrophysiological studies. Research shows that low prevalence targets are routinely missed across professional domains from medical screening to airport security. While the Low Prevalence Effect (LPE) is well-documented within individual tasks, how prevalence-induced expectations influence sequential tasks remains unclear. Four behavioural experiments employed a sequential paradigm consisting of letter discrimination and dot-probe detection tasks. Target prevalence, distractor confusability, feedback, and dot-probe eccentricity were manipulated to examine attentional resource distribution. Results demonstrated that low prevalence targets significantly impaired subsequent dot-probe performance through slower response times, decreased accuracy, reduced sensitivity, and more conservative response bias. Effects persisted despite the predictable dot-probe task, were partially moderated but not eliminated by feedback, and scaled linearly with prevalence imbalance. Interestingly, dot-probe eccentricity did not affect performance, suggesting effects were not due to spatial attention adjustments. A fifth experiment using electroencephalography (EEG) examined the neural underpinnings of these effects. Event-related potential (ERP) data revealed that low prevalence targets elicited larger P3a amplitudes, reflecting increased attentional capture, with P3a amplitude correlating with performance decrements. High prevalence targets elicited larger P3b amplitudes, indicating sustained working memory engagement. Early attentional processing (P1) predicted P3a responses for rare but not frequent targets, demonstrating a cascade of attentional modulation from early processing stages to subsequent orienting responses. Together these findings indicate that unexpected events temporarily capture attention through automatic mechanisms, depleting resources available for subsequent tasks. These results are consistent with attention-orienting mechanisms underlying expectancy violations, whereby prevalence imbalance affects sequential judgements through both automatic attentional capture and sustained working memory demands. Results have implications for professional visual search contexts where targets are rare but consequential, suggesting that prevalence-induced resource depletion may impact sequential judgements beyond the immediate task.

Item Type:	Thesis (Doctoral)
Additional Information and Comments:	Copyright © The Author 2026. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
Faculty / Department:	Faculty of Human and Digital Sciences > School of Psychology
Depositing User:	Matthew Adams
Date Deposited:	14 Sep 2026 08:22
Last Modified:	14 Sep 2026 08:22
URI:	https://hira.hope.ac.uk/id/eprint/4972

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