| Summary: | The disabling effects of schizophrenia, as well as the difficulty in addressing all the associated deficits through treatment are well documented. Recently more research has focused on characterising cognitive deficits related to schizophrenia, as due to their enduring nature, and relation to functioning ability they are viewed as a therapeutic target. The aim of this thesis was to investigate the ability of individuals diagnosed with schizophrenia, as well as in relation to the schizophrenia spectrum, to shift attention focus both within the visual field (covert attention) and by directing their eye-movements (overt attention). In particular the ability to use task information to modify strategies for better performance was examined. Participants, consisting of individuals with a diagnosis of schizophrenia, an age appropriate comparison group and students assessed for schizotypal traits, completed two covert cueing tasks, and two anti-saccade tasks, designed to measure both reflexive and voluntary attention shifts. Individuals with schizophrenia showed consistent impairments across the tasks, with lower sensitivity to targets and slower response time for the covert attention studies, and higher error rates and longer latencies for the anti-saccade tasks. Schizotypy scores were also related to some performance measures, with higher scorers exhibiting lower hit rates for the cueing study, and longer latencies in the classic anti-cue task. The inability to inhibit eye-movements was also consistently related to the schizophrenia spectrum. All participants, including those in the schizophrenia group, used the task information to change their attention strategies accordingly; this suggests that individuals with schizophrenia are able to use some degree of top-down voluntary control of both overt and covert attention. Thus strategic attention appears preserved in relation to the schizophrenia spectrum, but the basic deficits, which were shown to be consistent, could present a target for treatments as they are present even when participants are receiving medication.
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