The Association of Hemispheric Specialization and Cognitive Abilities with Regard to Sex, Hand Preferences and Birth Stress

Abstract

<p>The relationship of patterns of hemispheric specialization to verbal and non-verbal cognitive abilities were studied as well as the effects of birth stress on the etiology of left-handedness. Using verbal and non-verbal dichotic listening tests 28 right- and left-handed boys and girls with a mean age of 10.6 years, were assessed as being unilaterally or bilaterally organized for processing verbal and non-verbal material. The subjects were also assessed for verbal and non-verbal ability using standard intelligence tests. Birth records were obtained in order to assess whether birth stress resulted in perinatal anoxia, the agent for altering hand preference. It was found that:</p> <p>1) Boys may show a left ear effect for some nonverbal material but girls may not.</p> <p>2) Bilateral organization for processing non-verbal material is not necessarily correlated with poorer spatial ability in girls.</p> <p>3) The relationship of bilateral organization for processing verbal material with overall verbal ability were inconclusive.</p> <p>4) There is no evidence to indicate that birth stress and/or oxygen deficit are necessary for left-handedness to occur, since both right- and left-handers exhibit these factors to the same degree and at least some of the left-handers appear to show no evidence of birth stress at all.</p>