Neural representations of intermodal attention

• Main Author: Vibell, Jonas F.
• Published: University of Oxford 2006
• Subjects: 612.8
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491737

The research presented in this thesis was c.onducted to investigate the processing stages and mechanisms underlying attentional orienting to spatial locations and sensory modalities in vision and touch. All experiments involved the presentation of visual and tactile stimuli at bilateral locations while attention was being oriented to spatial locations or sensory modalities under different task loads. The simultaneous recording of ERPs enabled the detection of millisecond differences in visual and tactile potentials. Chapter 3 compared attention to sensory modalities and spatial locations using an oddball paradigm where the analyzed stimuli were identical between conditions. Results showed many similarities between both types of attention, but suggested that early differences might exist under higher perceptual task load. Chapter 4 consisted of behavioral experiments developing a temporal order judgment (Tal) paradigm for simultaneous ERP recordings. This enabled looking at brain activations from attention orienting using a new type of paradigm emphasizing perceptu,al temporal judgments. Chapters 5 & 6 used TOls to investigate attention to sensory modalities and spatial locations under a high perceptual load. Chapter 5 investigated the influences of attention to sensory modalities on early visual potentials. It was designed to evaluate the mechanisms of early attentional modulations and to examine the veracity of Titchener's (1908) law of prior-entry, which claims that attention makes stimuli .come into consciousness earlier. Results showed that attention to sensory modalities speeds-up early visual potentials thereby confirming the law of prior entry and suggesting that attention can operate by different types of mechanisms in perceptual processing- by speeding-up latencies and by enhancing amplitudes. These results were confirmed by the experiment in chapter six using spatial attention. All in all, this thesis adds to the available empirical and theoretical research related to the flexibility in the stages and mechanisms of attentional modulation in the brain.