Two versions of the Tower of Hanoi task were used to investigate
different components of learning and problem solving in schizophrenia.
Prior studies have suggested that a three-disk version (Tower 3), which
involves primarily problem-solving abilities and planning, is
preferentially sensitive to frontal lobe lesions and that the more
difficult four-disk version (Tower 4), which involves "learning by doing,"
is sensitive to basal ganglia disease. Schizophrenic patients performed
significantly worse than normal subjects on Tower 3 and Tower 4. However,
they performed at least as well relatively on Tower 4 as on Tower 3,
indicating that level of difficulty per se does not account for their poor
performance on these tasks. Moreover, they eventually attained perfect or
near-perfect performance after four days of repeated administration. Their
relatively stronger performance on Tower 4 may have reflected an ability to
acquire a procedure and, as such, suggests greater preservation of basal
ganglia function than of prefrontal function.