Recent studies have reported abnormal implicit learning of sequential
patterns in patients with schizophrenia. Because these studies were based
on visuospatial cues, the question remained whether patients were impaired
simply due to the demands of spatial processing. This study examined
implicit sequence learning in 24 patients with schizophrenia and 24
healthy controls using a non-spatial variation of the serial reaction time
test (SRT) in which pattern stimuli alternated with random stimuli on
every other trial. Both groups showed learning by responding faster and
more accurately to pattern trials than to random trials. Patients,
however, showed a smaller magnitude of sequence learning. Both groups were
unable to demonstrate explicit knowledge of the nature of the pattern,
confirming that learning occurred without awareness. Clinical variables
were not correlated with the patients' learning deficits. Patients
with schizophrenia have a decreased ability to develop sensitivity to
regularly occurring sequences of events within their environment. This
type of deficit may affect an array of cognitive and motor functions that
rely on the perception of event regularity. (JINS, 2005,
11, 659–667.)