We report the case of a patient who suffered an ischemic accident resu
lting in damage to the anterior part of the corpus callosum and to the
white matter in the posterior right hemisphere. Recognition of two-di
mensional haptic stimuli explored with the right hand was severely imp
aired. The deficit was not specific to the type of stimuli, since lett
ers, digits and geometrical shapes were not correctly recognized. Poor
performance was not due to a specific mode of haptic exploration, sin
ce deficits were also observed without active manipulation of the stim
uli. In contrast, the patient correctly named visual letters presented
in the right visual hemifield (left hemisphere), and recognized three
-dimensional common objects palpated with the right hand. Comparable r
esults were observed in a surgical split-brain patient tested as a con
trol. We conclude that (i) the construction of spatial representations
of haptic stimuli, such as two-dimensional stimuli or three-dimension
al block letters, cannot be fully realized in the intact left hemisphe
re, this ability requiring the contribution of both hemispheres, and (
ii) tests for correct naming of common objects do not provide sufficie
nt evidence to establish the integrity of the system involved in the i
dentification of haptic information processed by the right hand of spl
it-brain patients. (C) 1997 Elsevier Science Ltd.