McCarthy, Marie Majella; (1996) Cross modal aspects of attention in normal individuals and those with multiple sclerosis. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Cross modal aspects of attention were investigated in normal individuals and in those with multiple sclerosis. For clarity, the thesis is divided into two sections. In the normative section two main issues are addressed: (1) Are the mechanisms responsible for the control of attention in vision and audition functionally independent. (2) Is attention covertly oriented in the auditory modality in the same manner as in the visual modality. A modification of Posner's cue validity paradigm (Posner, 1978; 1980) was employed. Five experiments were conducted with normal subjects which systematically varied the following factors: the modality of presentation of the cue and of the target (visual or auditory); the congruence of the cue (valid or invalid); the nature of the cue type (spatial or semantic) and the predictive value of the cue (low or high predictability). Manual reaction time was the dependant variable in all of the experiments. The results provided preliminary evidence in favour of the hypothesis that there may be functionally independent mechanisms for the control of attention in vision and audition. It was also demonstrated that the auditory modality was capable of covert shifts of attention but this effect was fragile and sensitive both to the nature and predictability of the cue. In the clinical section two further issues are addressed: (1) What is the nature of impaired and intact attentional abilities in patients with multiple sclerosis (MS). (2) Do MS patients show the same cueing effect within the cross modal paradigm as normal subjects. The Test of Everyday Attention (Robertson et al., 1994) was employed to investigate patients' global attentional abilities. Contrary to what was expected, all of the MS patients showed preserved ability on measures of sustained attention, while their performance on measures of divided attention was impaired. While the pattern of their performance on the cross modal paradigm did not directly mirror that of normal subjects, an interesting benefit in favour of cross modal trials by comparison to within modality trials was reported. The findings again supported a modality specific rather then a supramodal view of attention.

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