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Attention without awareness

Bahrami, B.; (2009) Attention without awareness. Doctoral thesis , UCL (University College London).

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Judging by introspection and intuition, most of us would agree that the we become conscious of events in the external physical world when we pay attention to them and things we notice (i.e., become conscious of) are the ones that attract our attention. A long tradition of investigations in psychology and neuroscience also confirm that attention and awareness go hand in hand. Recently, however, the validity of this intuition has been questioned. This thesis addresses the hypothesis that attention and awareness might be disentangled at behavioural and neurobiological levels. Two main questions were: (1) does allocation / withdrawal of attention to / from unconscious stimuli affect the contents of subconscious processing and if so, could one demonstrate such modulations at the perceptual levels of processing? (2) What are the neural substrates of attentional selection of unconscious perception? In order to address these questions I adopted the framework of Load Theory combined with a recently developed technique called Continuous Flash Suppression (which combines binocular rivalry with dichoptic masking allowing for prolonged periods of unconscious exposure to visual stimuli). In 7 behavioural experiments I demonstrated (1) orientation-specific adaptation to unconscious gratings (rendered invisible by CFS); (2) such subconscious orientation processing was modulated by attentional load in a concurrent orthogonal foveal task as well as by sustained spatial attention. Finally, using functional magnetic resonance imaging (fMRI) I showed that human primary visual cortex (Vl) response to invisible stimuli was also modulated by attentional load. My findings join a-number of recent works in challenging the traditional view that attention and awareness are one and the same as well as the idea that attention acts as the gate-keeper to awareness. They also support the suggestion that neither the availability of attentional capacity for stimulus processing nor allocation of spatial attention can be a sufficient condition for awareness.

Type: Thesis (Doctoral)
Title: Attention without awareness
Language: English
Additional information: Permission for digitisation not received
UCL classification: UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Div of Psychology and Lang Sciences > Institute of Cognitive Neuroscience
URI: https://discovery.ucl.ac.uk/id/eprint/17248
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