Roger E Graves

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Cohen, in a now classic paper on statistical power, reviewed articles in the 1960 issue of one psychology journal and determined that the majority of studies had less than a 50-50 chance of detecting an effect that truly exists in the population, and thus of obtaining statistically significant results. Such low statistical power, Cohen concluded, was(More)
We used multidimensional statistical procedures to study semantic and lexical processes underlying word retrieval in verbal-fluency performance. Forty healthy participants were given a two-choice letter task (i.e., generate items beginning with the letter 'A' or 'F', in any order) and a two-choice category task (i.e., generate animal or fruit names, in any(More)
An abnormal facilitation of the spreading activation within semantic networks is thought to under-lie schizophrenics' remote associations and referential ideas. In normal subjects, elevated magical ideation (MI) has also been associated with a style of thinking similar to that of schizotypal subjects. We thus wondered whether normal subjects with a higher(More)
A high proportion of normal subjects have speech expression controlled predominantly by the left hemisphere. Since the left hemisphere also has stronger control of the right side of the lower face, it might be expected that normal subjects would show a right-sided asymmetry in mouth opening during speech. This hypothesis was tested by measuring lip opening(More)
PRIMARY OBJECTIVE To determine the extent to which participation in a multidisciplinary rehabilitation programme and patient characteristics predict improvement in community integration following mild-to-moderate traumatic brain injury (TBI). RESEARCH DESIGN A non-randomized case-control study was conducted employing a pre-test-post-test multiple(More)
Prior research has shown associations between higher creativity (e.g., semantic association, verbal fluency), higher schizotypy (e.g., magical ideation), and relatively stronger right hemisphere laterality measures--when each of the three pairings has been studied individually. Our prior study related creativity and schizotypy to signal detection theory(More)
Clinical observation of aphasic patients often shows a dissociation between impaired propositional speech and preserved automatic speech. The question of differing hemispheric control between these speech tasks was examined by measuring asymmetry in facial muscle activity. In spite of right-sided facial palsy, greater opening of the right side of the mouth(More)
This paper examines the idea that an important dimension of human cognition is the amount of objective evidence required for perception of meaningful patterns. At the clinical extreme of this dimension are patients with hallucinations and delusions who experience perception with no external evidence and see connections between objectively unrelated events.(More)