The effects of sleep deprivation on visual perception and metacognition

Bigica, Marco 2022. The effects of sleep deprivation on visual perception and metacognition. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Sleep serves fundamental functions for the human brain and lack of sleep leads to impairments in cognitive and behavioural tasks. Yet, the mechanisms that underlie such impairments as well as the extent of cognitive domains affected by sleep deprivation (SD) are still not completely understood. To address these gaps, this thesis aims to investigate the effects of SD on two important but previously overlooked cognitive functions: visual perception and metacognition - the ability to self-monitor performance. Investigation of visual perception focuses on the perceptual processing hierarchy. In Chapter 3, I explore the effects of SD on low-level visual functions (e.g. orientation sensitivity), using four psychophysical tasks assessed before and after a night of SD. I find differential effects of SD on performance between tasks, revealing selective impact of sleep loss on low-level perceptual functions. Chapter 4 investigates the high-level perceptual ability to categorise objects (faces vs scenes). Using functional Magnetic Resonance Imaging (fMRI), I observe that brain activity in regions specialized in face and scene processing is altered by SD, in parallel to a reduction in categorisation performance. Another aim of this thesis is to assess the impact of SD on metacognitive ability. This is investigated in Chapter 5 using confidence ratings in perceptual judgements to measure the correspondence between response confidence and response accuracy. Results show that after SD individuals become less able to discriminate accurate from inaccurate temporal perceptual judgements, reflecting poorer self-monitoring capacity after sleep loss. Chapter 6 brings together results of this thesis and provides suggestions to tackle novel questions in future research. Overall, this thesis shows novel and detrimental effects of sleep loss at different levels of the perceptual processing hierarchy as well as on metacognition, extending our comprehension of the range of cognitive deficits caused by sleep deprivation.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Psychology
Date of First Compliant Deposit:	13 July 2023
Last Modified:	13 Jul 2023 10:36
URI:	https://orca.cardiff.ac.uk/id/eprint/161005

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