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Title: Impaired and intact function in prosopagnosia : an analysis of overt and covert attention
Author: Griffin, H. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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This thesis investigates whether, in addition to the resulting cognitive deficit, abnormal attentional processes are a feature of prosopagnosia. To this end the cognitive and eye-movement performance of PHD, patients with prosopagnosia, and neurologically intact control subjects were assessed. The shifting of attention without eye-movement (covertly) in response to visual stimuli is a long established phenomenon. In addition to spatially informative cues, such as arrows, social stimuli, such as faces, can also act as attentional cues. PHD’s attentional response to peripheral cues and central arrow, object and face cues was investigated and found to be the same as controls’ despite his impaired face processing. This study therefore contradicts the theory that an intact face processing system is necessary for social cueing. Rapid attentional shifting in response to non-social, uninformative object cues suggests that an inherent directionality can be extracted from objects, including faces, that elicits attentional cueing. The redirection of gaze (overt attention) is known to be functional in learning faces. PHD’s eye-movements when making judgements for faces and cars were found to be abnormal compared to controls: PHD looked at fewer face features and biased his looking towards one eye. PHD was therefore trained on a rehabilitation eye-movement strategy that directed his gaze to all internal face features in a particular order. Use of this strategy improved PHD’s face recognition, which then significantly declined when the strategy was abandoned. The neural basis of this strategic advantage was investigated in PHD using an event related potential (ERP) design. Short-term effects of face repetition were found, which appeared larger for faces viewed using the strategy than faces viewed freely. The significance of these findings for our understanding or prosopagnosia and the potential of eye-movement strategies for rehabilitation are discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available