We examined the ability of 23 schizophrenia patients and 24 healthy
controls to exert intentional inhibition of prepotent responses in the
Think-No-Think (TNT) paired-associate learning paradigm (Anderson &
Green, 2001). TNT manipulates the frequency (1,
8, 16 times) of intentional attempts to suppress (inhibit) some target
words and to respond to most cue words. Following a TNT practice-phase,
recall of suppressed words was tested in two ways, using the same cue
words initially learned, and the category name plus letter-stem of the
target words. Inhibition of prepotent responses was also examined in a
random number generation (RNG) task. In TNT, speed results showed longer
reaction times after 16 suppress attempts in patients, not in controls,
reflecting increased difficulty with retrieving the memory traces of the
overridden items. In accuracy, no between-groups differences were
evidenced, and overall patterns replicated those of Anderson & Green.
In RNG, patients produced more stereotyped responses and ascending and
descending counting than controls, pointing to on-line failures to inhibit
prepotent responses. These findings suggest that schizophrenia
patients' difficulties to inhibit prepotent responses appear
specific, not widespread, the intentional inhibition addressed in TNT
being preserved, and on-line inhibition in RNG being impaired.
(JINS, 2007, 13, 277–287.)This paper was presented at the 4th International Conference
on Memory, July 16–21, 2006, in Sydney, Australia.