Is interhemispheric transfer of visuomotor information asymmetric? Evidence from a meta-analysis

Meta-analyzed 16 studies with 320 Ss, using a simple unimanual reaction time (RT) paradigm and lateralized visual stimuli, to estimate the interhemispheric transfer time in normal right-handed persons. There was a significant overall RT advantage of the left visual field over the right visual field and of the right hand over the left hand. These asymmetries can be explained in terms of the left hemisphere having direct control of only the contralateral hand through the cortico-spinal path, while the right hemisphere directly controls both hands because of a substantial contribution of the uncrossed cortico-spinal pathway. A 2nd explanation is that these asymmetries relate to an asymmetry of interhemispheric transmission of visuomotor information, with transmission from the right hemisphere to the left being faster in the reverse direction. (PsycLIT Database Copyright 1992 American Psychological Assn, all rights reserved