A left to right hemisphere callosal transfer deficit of nonlinguistic information in alexithymia.

Schalling-Sifneos and MMPI Alexithymia Scales were used to screen 730 Japanese subjects. The 27 subjects scoring highest and the 26 scoring lowest on both scales were designated high and low alexithymic respectively. The two groups were tested by tachistoscopically presenting them with a lateralized visual matching task, which incorporated both linguistic and nonlinguistic stimuli. Differences in ipsilateral and contralateral hand reaction times were used as an indicator of callosal transfer speed. The results indicated that the two groups did not differ in the callosal transfer of linguistic information. They differed significantly, however, in the right to left hemisphere transfer of nonlinguistic information. This result is suggestive of a physiological basis in alexithymia.