City Research Online

Abstract

Visual Working Memory (visual WM) is an ability to encode and temporarily maintain visual information. There is some evidence that early perceptual processes make an important contribution to successful WM performance. However, perceptual contributions to WM are not yet fully understood.

In vision, signals originating from three classes of photoreceptors in the retina (L, M and S-cones) are combined into three distinct mechanisms, which form the fundamentals of visual perception. These mechanisms are the two opponent chromatic mechanisms (L – M and S – (L + M) and an achromatic, luminance mechanism (L + M). Vision science has been long concerned with properties of these mechanisms and how they contribute to the perception of the world. Despite this, there was little interest to date in how these mechanisms contribute to creating memory representations, i.e. after the visual stimulus has disappeared from the visual field. In a series of experiments presented in this thesis, a differential contribution of three post-receptoral mechanisms to visual WM was investigated. It was hypothesised that luminance signals will prove to be more efficient in their contribution to WM encoding, maintenance and retrieval than opponent chromatic signals. This was investigated using a variety of methodologies, from psychophysical measurements and behavioural responses to recordings of neural activity using electroencephalography (EEG).

Results of the experiments have shown that indeed, remembering abstract shapes designed to excite the luminance mechanism contributed to better WM performance comparing to remembering shapes designed to excite the opponent chromatic mechanisms. EEG recordings have shown that this luminance benefit starts already during WM encoding, although later WM stages are likely to benefit as well. The findings demonstrate that luminance signals provide an advantage over opponent chromatic mechanisms in working memory processing.

Publication Type:	Thesis (Doctoral)
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
Departments:	Doctoral Theses School of Health & Psychological Sciences > Psychology School of Health & Psychological Sciences > School of Health & Psychological Sciences Doctoral Theses

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