Dual functional brain asymmetry refers to the notion that in most individuals the left cerebral hemisphere is specialized for language functions, whereas the right cerebral hemisphere is more important than the left for the perception, construction, and recall of stimuli that are difficult to verbalize. In the last twenty years there have been scattered reports of sex differences in degree of hemispheric specialization. This review provides a critical framework within which two related topics are discussed: Do meaningful sex differences in verbal or spatial cerebral lateralization exist? and, if so, Is the brain of one sex more symmetrically organized than the other? Data gathered on right-handed adults are examined from clinical studies of patients with unilateral brain lesions; from dichotic listening, tachistoscopic, and sensorimotor studies of functional asymmetries in non-brain-damaged subjects; from anatomical and electrophysiological investigations, as well as from the developmental literature. Retrospective and descriptive findings predominate over prospective and experimental methodologies. Nevertheless, there is an impressive accummulation of evidence suggesting that the male brain may be more asymmetrically organized than the female brain, both for verbal and nonverbal functions. These trends are rarely found in childhood but are often significant in the mature organism.

Sex differences in human brain asymmetry: a critical survey

Normative Data Stratified by Age and Education for Two Measures of Verbal Fluency: FAS and Animal Naming

Pseudoneglect: effects of hemispace on a tactile line bisection task.

The neuropsychologic, neuroanatomic, and neurophysiologic correlates of achromatopsia were studied in two patients. Prosopagnosia accompanied the color perception defect in the bilateral case but not in the unilateral one. No other neuropsychologic disturbance was present in either case. The lesions compromised the ventromedial sector of the occipital lobe in both cases. Cerebral evoked responses produced by pattern shift stimulation were normal for black and white but abnormal for red and green, when stimulation was given in the achromatopsic field.

Central achromatopsia Behavioral, anatomic, and physiologic aspects

Effects of protein and carbohydrate meals on mood and performance: interactions with sex and age.

Lateral differences in tactile directional perception

The Reliability of Reaction Time Determinations

Stereopsis and the perception of anomalous contours.

A battery of mental tests was given to groups of younger (16–44 years) and older (48–60 years) control and cerebral diseased patients. Each patient in the younger cerebral diseased group was matched individually with an older cerebral diseased patient for type and side of lesion. Each patient with cerebral disease was matched individually with a control patient for age, educational level and sex. Differences in level of test performance related to age were generally greater for cerebral diseased than for control patients. Differences in level of test performance related to diagnostic category were generally greater for older than for younger patients. Analysis disclosed a significant overall interactive effect of age and cerebral disease on the performance of mental tests, supporting the hypothesis that acquired cerebral disease has more severe behavioral consequences in older than in younger persons.

K. de S. Hamsher

Papers

Lateral differences in tactile directional perception

The Reliability of Reaction Time Determinations

Stereopsis and the perception of anomalous contours.

Interactive effects of age and cerebral disease on cognitive performances