Biomedical subjects
Publications and source records attributed to E R McMeekan.
Patients recently recovered from schizophrenic or manid-depressive psychoses showed larger ear difference scores than normal controls on a dichotic listening test, i.e. when asked to identify dissimilar words fed synchronously to the two ears. The possible significance of the finding is discussed, in relation both to hemispheric organization and to other aspects of cognitive activity which may underlie performance on the task.
In so far as ear asymmetries on dichotic listening reflect cerebral dominance for language, the present evidence indicates a progressively decreasing incidence of left hemisphere dominance in right handed, mixed handed and left handed individuals. In the absence of a family history of sinistrality there are no indications that the degree of dominance is reduced in left handers or mixed handers when compared to right handers, nor that right hemisphere dominance is less securely established than left hemisphere dominance. Among strong left handers with a family history of sinistrality, however, ear difference scores are significantly smaller, indicating reduced lateralization or bilateral representation of language in such individudals. This applies equally in left dominant and right dominant left handers.
A brief survey, using a standardized questionnaire, has been made of hand preference patterns in a series of patients admitted to hospital with functional psychiatric disorders. A small but significant shift towards left hand preference has been observed, more marked in the young patients and virtually confined to the males. Psychotic patients show such a shift more clearly than neurotic or personality disordered patients. Simple genetic factors do not appear to be responsible for these sinistral tendencies. The findings are discussed in relation to possible acquired abnormalities of functional brain organization.