Space-based and feature-based attentional selection in perception and working memory

McCants, Cody Walker (2019) Space-based and feature-based attentional selection in perception and working memory. Doctoral thesis, Birkbeck, University of London.

Abstract

In order to manage the high amount of sensory input we experience, attention processes enable the selective prioritization of goal-relevant information over irrelevant distractions. Two fundamental ways in which this is accomplished is by focusing attention at particular locations in the environment (spatial attention) or by focusing on specific forms of information (feature-based attention). Despite many decades of research examining these mechanisms, however, they have been seldom directly compared particularly in relation to their underlying neural mechanisms. In this thesis, the neural correlates of spatial and feature-based attentional selection for perception and working memory maintenance processes are contrasted. Event-related potential (ERP) components from electroencephalography (EEG) recordings are used as markers of such processes. The N2pc component is used to measure lateralised attentional selection to targets defined by one or a combination of spatial locations and features in perceptual tasks, whilst the CDA component is used to measure the active maintenance of target objects/locations in working memory tasks. In total, this thesis contains three lines of investigation. The first line compares these ERP components for attentional selection to targets defined by spatial locations and features and reveals that in many contexts, spatial attention is processed similarly to featural attention with a few notable exceptions (Chapter 2). The second line of enquiry examines how spatial configural information affects feature-based attentional selection when it is a critical component for successful goal-directed search, revealing that such information can guide attentional selection for some feature dimensions (Chapter 3). Finally, the third line of enquiry compares how spatial and feature-based attention influences visual perceptual and post-perceptual working memory processes (Chapters 4 and 5). This investigation lead to the observations that spatial attentional templates are quicker to guide attention when there is no SOA between the cue and target display onset, and that the two types of attention have similar working memory capacity limitations These findings culminate to provide one of the first direct comparisons of the neural correlates of attention to spatially or featurally-defined information, thereby expanding the current understanding of how spatial/feature-based attention operates. By measuring real-time event-related responses during these task contexts, the present thesis highlights the independent nature of spatial and feature-based attention and their qualitative similarities, but also how they interact upon one another under some circumstances. The findings aid the literature by shedding light on the argument perceptual and post-perceptual processes involved in spatial attention are qualitatively different from featural attention processes.

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