Individual differences in callosal efficiency: Correlation with attention

Previous studies of clinical populations and normal children have suggested that the efficiency of callosal transfer correlates with the ability to su stain attention. The purpose of the present study was to determine whether the same might be true for normal adults. Subjects were 42 right-handed adu lts. The efficiency of the transfer via the anterior callosum was assessed on a bimanual coordination task. The efficiency of the posterior callosum w as measured on a tachistoscopic task that required subjects to compare two lines when both were presented either to the same visual held or to opposit e visual fields. Sustained attention was measured on a vigilance task in wh ich the time between target presentations (ISI) was varied. Performance on the bimanual task correlated with the ability to sustain attention over the entire 20 min of the vigilance task. The efficiency of the posterior callo sum was related to the ability to detect targets that occurred after relati vely long ISIs. (C) 1999 Academic Press.