Visual field differences in verbal tasks: Effects of task familiarity and sex of subject

Four experiments using normal subjects investigated differences in magnitude of the right visual field (RVF) superiority as a function of word material (frequency and concreteness/imageability status), nonword letter strings (some of which were homophonic with nonpresented real words), and type of task (overt naming or lexical decision with discriminatory manual responses) as well as sex of the subject and the subject's familiarity with the material. Both latency and error measures showed that RVF superiority was more consistent when overt naming was required and with male subjects. For female subjects engaged in lexical decisions, a left visual field (LVF) superiority was often apparent, especially in the first half of an experimental sequence; when actually naming the items aloud, they showed field asymmetries similar to males. Except from an analysis of errors, there was little evidence to support differential right hemisphere mediation of high frequency concrete/imageable materials. It is suggested that in females, right hemisphere space normally reserved for visuospatial processing may have been invaded by secondary speech mechanisms. These mechanisms appear to operate at an essentially lexical level and may act in a supportive or auxiliary capacity for difficult or unfamiliar material; they seem to be equally concerned with both phonological and graphological processing and may account for the well-known female superiority in verbal tasks and inferiority in visuospatial tasks. Other findings are discussed such as the degree of consistency of the field differences, both for the same subjects and for the same stimulus materials under different task requirements and experimental conditions.     

Right-hemisphere language: Familial and nonfamilial sinistrals,cognitive deficits and writing hand position in sinistrals,and concrete-abstract,imageable-nonimageable dimensions in word recognition. A review of interrelated issues

While left-hemisphere language dominance is more general than dextrality, and reversed dominance is less frequent than sinistrality, there are disputes in both the clinical and the experimental literature on a number of related issues which pertain to a possible language contribution from the minor hemisphere. These issues include the nature and extent of bilaterality in sinistrals, whether this is more pronounced in the strongly or weakly sinistral, and in those with or without other sinistral close relatives, whether sinistrality is largely or at all a consequence of birth stress, whether sinistrals differ from dextrals in visuospatial or even verbal skills, Levy's (1978) hypothesis that a knowledge of the hand position employed in writing (hooked or noninverted) may accurately predict language lateralization in sinistrals, and the possible extent of a minor hemisphere contribution to the recognition of high frequency, concrete, or imageable nouns. Findings relating to the above issues are reviewed, and it is concluded that much of the current confusion stems from poor control of subject factors such as sex, strength and family history of handedness, and nature of stimuli and their mode of presentation.     

Mirror reading in right and left handers: Are sinistrals really superior?

While left handers, where they do in fact appear to differ from right handers in cognitive function, have generally been found to be slightly inferior on verbal tasks, there are some reports of a sinistral superiority for nonverbal or spatial abilities. Tankle and Heilman (Brain and Language, 1982, 17, 124-132) report a sinistral superiority in (obligatory) reading of left-right mirror-reversed text. However, in an investigation which included various other forms of geometrical transformation of the written word, we find that strong familial sinistrals are either not different from or even slightly inferior to dextrals in reading most transformations, including left-right mirror reversals.     

Synonym and antonym pairs in the detection of dichotically and monaurally presented targets: Competing monaural stimulation can generate a substantial right ear advantage

Aligned pairs of spoken words were presented, and the subject timed in detecting the presence or absence of a prespecified target. The target, if present, was paired with either its synonym or its antonym or an unrelated word. If the target was absent, mutually synonymous, antonymous or unrelated word pairs occured. In experiment 1, presentation of the word pairs was dichotic, and in experiment 2 the same stimuli were now systematically presented to a single ear (competing monaural stimulation). In both cases a strategy of divided attention was imposed with respect to the words. A powerful REA was obtained in the second experiment, demonstrating that this phenomenon does not depend upon occlusion of the ipsilateral by the contralateral auditory pathways (Kimura 1961), but that competition within ears is sufficient. Secondly, the nature of the effect (facilitatory or interfering) from a co-present synonym or antonym of the target depends markedly upon how the ears are stimulated, in partial contrast to and extending the results of Lewis (1970).