The neural basis of attention and perception in the human brain

• Main Author: Watkins, S.
• Published: University College London (University of London) 2011
• Subjects: 612.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.565407

Being able to focus on the task at hand while retaining the ability to respond to salient task-irrelevant stimuli is critical to successful human behaviour. It is vital that animals and people can quickly redirect their attention when faced with novel or potentially threatening stimuli. In this thesis I use a range of fMRI techniques including retinotopic mapping and multivariate analysis to investigate the behavioural and perceptual consequences of task irrelevant stimuli in audition and vision. Initially I describe two fMRI experiments investigating the cortical areas mediating behaviourally defined attentional capture by a task-irrelevant auditory and visual stimulus. I then go on to demonstrate that task irrelevant auditory stimuli can have a profound effect on both visual perception and processing in early visual cortical areas. In particular I demonstrate for the first time that an auditory induced change in visual perception can influence processing in the primary visual cortex. Further more, I demonstrate that auditory timing can alter the perceived direction of visual apparent motion and that such behavioural changes can be decoded from V3 and MT+. Finally I demonstrated that in the situation where an auditory stimulus has no behaviour or perceptual relevance to visual processing early visual areas do not encode information about the auditory stimulus. Taken together these findings indicate that task irrelevant distractors can have a significant effect on behaviour and perception.