Previous research had demonstrated diminished interhemispheric
Stroop effects in individuals with agenesis of the corpus
callosum (ACC), suggesting an important role for the callosum
in interhemispheric color-word and color-patch interactions.
However, this outcome rested on the results of only 1 ACC
participant, who had normal intelligence and a minimum
of other neuropathology. In the research reported herein,
the role of the corpus callosum in interhemispheric Stroop
interference and facilitation was investigated in 9 individuals
with complete or partial ACC and normal intelligence, and
in non-ACC controls. Congruent, incongruent, or neutral
stimulus pairs were presented either unilaterally (color-patch
and color-word in the same visual field) or bilaterally
(color-patch and color-word in different visual fields).
Both unilateral and bilateral (interhemispheric) Stroop
interference were found for both ACC and non-ACC groups,
with no significant difference in magnitude, indicating
that extracallosal pathways are sufficient for mediating
this phenomenon. It is suggested that the anterior commissure
is a more likely candidate for the interhemispheric transmission
of the semantic information resulting in Stroop interference.
(JINS, 2001, 7, 302–311.)