Right hemispheric specialization for mental imagery: A review of the evidence

An implicit assumption in the literature on functional hemispheric asymmetry is that the right hemisphere plays a special role in mental imagery. Using a definition of mental imagery as quasi-perceptual experience, we draw distinctions among visual imagery, visual recognition memory, and visuospatial abilities. We then review the research literature to evaluate the hypothesis that mental imagery is a specialized function of the right cerebral hemisphere, and find that it receives little unambiguous support. Case reports of loss of imagery are no more frequent with right than with left unilateral brain damage. Systematic studies of brain-injured patients provide some support for the hypothesis, but are also consistent with the alternative hypothesis of bilateral representation of imagery. Commissurotomized patients report dreaming and being able to form visual images. Behavioral and psychophysiological studies of non-brain-injured patients either fail to provide evidence in favor of the hypothesis or can be interpreted as compatible with the alternate hypothesis of bilateral hemispheric involvement in imagery. We conclude that there is, presently, insufficient empirical basis for considering imagery a right hemispheric function. We then discuss implications of this conclusion for future research.     

Writing hand posture and four indexes of lateral preference

The relationship between writing hand posture and lateral preference for hand, foot, eye, and ear was examined in a sample of 3709 college undergraduates. A markedly different pattern of lateral preferences was observed in left-handed males and females as a function of hand posture. Left-handed male inverters displayed a tendency toward more leftward lateral preferences in all four indexes; while it was found that hand inversion during writing in left-handed females reflected, if anything, a tendency toward more rightward lateral preferences.     

Hemiretinal differences in face recognition: accuracy versus reaction time

A face-recognition task involving monocular presentation of laterally displaced stimuli yielded a nasal hemiretinal advantage for reaction time for correct identifications, but a temporal hemiretinal advantage for accuracy (d'). These hemiretinal effects, in conjunction with eye dominance, could in principle distort or obscure interpretations of hemispheric processing differences obtained with binocular stimulation.     

Effects of educational and career exploration system on vocational maturity

An experimental group of 792 tenth graders spent from 1 to 17 hr (average 3 hr) on ECES, a computer-based educational and occupational exploration system.Gains on a test of vocational maturity administered at the beginning and end of the school year were compared with a control group of 1453 tenth graders, matched on relevant variables. ECES users showed larger gains than nonusers in (1) degree of planfulness and (2) knowledge and use of resources for career exploration, as measured by the Career Development Inventory, not in information about education, occupations and career decision making. Gains were related to amount of time spent on ECES but male-female differences were not exhibited.     

Immediate and delayed recognition of visual stimuli in poor and normal readers.

The present study investigated the hypothesis that specific reading disability is attributable to inadequate visual memory. Previous research had demonstrated that poor readers sustain no basic dysfunction in visual perception, but there was need to evaluate the possibility that deficiencies in letter and word recognition result from disorder in long-term visual storage. Adopting a format employed in a previous study, randomly arranged Hebrew letters were presented to poor and normal readers unfamiliar with Hebrew, and both groups were asked to demonstrate retention for these stimuli on three separate occasions: immediately after initial presentation, 24 hours later and 6 months later. As a control measure, the performance of the non-Hebrew subjects was compared with that of normal readers familiar with Hebrew letters. It was found that retention in the non-Hebrew groups was equivalent under all of the temporal conditions, but the performance of both was poorer than the Hebrew groups under the immediate and 24-hour conditions. However, none of the reader groups differed in the case of retention after a 6-month delay period. It was concluded that deficient visual memory is an unlikely source of specific reading disability, and alternative explanations of the disorder were considered.