Brain Mechanisms of Subjective Visual Awareness and Visual Attention

Abstract

Our psychological processes are sometimes accompanied by a sense of awareness, a property which is still poorly understood. The experiments presented in this dissertation contribute to our emerging understanding of the behavioral and brain basis of visual awareness, with a special focus on its relationship with visual attention. First, in a series of a behavioral experiments, the functional relationship between attention and awareness is considered. The results show that attention is less well controlled in the absence of awareness, contradicting the notion that awareness is an ‘epiphenomenon’ - a property that accompanies mental processes but does not interact with them. Then, a series of brain imaging and brain stimulation studies investigate the role of the temporoparietal junction (TPJ) in awareness. These studies show that temporary disruption of the TPJ with transcranial magnetic stimulation (TMS) interferes with visual awareness, and that the involvement of the TPJ in visual awareness cannot be accounted for as an artifact of visual attention. These studies also investigate how the involvement of the TPJ in awareness relates to its involvement in a range of other cognitive processes, and how these processes are supported by a network of other brain regions throughout the parietal and frontal cortex.