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Abstract:
Studies have shown schizophrenia patients to manifest verbal
memory deficits that extend beyond the generalized cognitive
deficit in the disorder. The nature of verbal memory deficits in
schizophrenia is unclear. This study involved recording the
behavioral responses and brain electrical activity of schizophrenia
and control subjects while they completed a task requiring the
encoding, recall, identification, and recognition of words (similar
to Paller et al., 1995). During encoding subjects judged the size
of named objects. Subjects then spontaneously recalled the named
objects. Schizophrenia patients performed worse than control
subjects in both accuracy of judgments during encoding and number
of recalled objects. To test repetition priming effects independent
of conscious recollection of words, subjects completed a word
identification task (word vs. nonword). Control and schizophrenia
subjects performed equally well at word identification and
repetition priming effects on reaction time were evident in both
groups. The final phase of the task assessed conscious recollection
of words. Unlike the recall phase of the task, schizophrenia
patients performed comparably to control subjects in correctly
identifying words as previously presented and not previously
presented. Because schizophrenia patients exhibit intact
recognition of previously presented words but perform poorly in
free recall of the same material, verbal memory deficits in
schizophrenia may result from a retrieval dysfunction. Preliminary
analyses of event-related potentials elicited during encoding, word
identification, and recognition are consistent with a spontaneous
retrieval deficit in schizophrenia.
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