The disconnection syndrome. Basic findings reaffirmed.

Recent challenges to the traditional view of the disconnection syndrome have been based primarily on evidence of information shared between the hemispheres in commissurotomy patients L.B. and N.G. of the West Coast series. In order to evaluate the generality of these claims, patients J.W., V.P. and D.R. were tested using a series of experiments which replicated and extended some of the experiments carried out in the West Coast series. Using comparisons of numerical identity and value as the model tasks, we found no indication that the separated hemispheres of J.W. or D.R. could share information on any of the tasks they performed. V.P., who has spared callosal fibres and has shown highly specific transfer in previous investigations, performed above chance (60%) in one out of three between field conditions. Together the data fail to support the claims that split-brain patients show evidence of unified cognitive functioning particularly for more abstract, nonperceptual tasks. The data are consistent with the traditional view of the corpus callosum as the primary interhemispheric pathway by which sensory and high-level cognitive integration is achieved.