Assessing a minimal executive operation in schizophrenia

The minimal cognitive operation of thinking of a just-seen stimulus (refreshing) was studied in 24 patients with schizophrenia and 24 normal controls. Verbal response times were measured when participants read a word, read a word immediately again, or refreshed a word just after it was no longer present. Patients showed equal priming as controls in reading a word for the second time and were slower than controls to say a word only in the refresh condition. On a surprise test, participants were asked to recognize the words they had seen previously and to give Remember, Know, or Guess responses according to whether they recognized words on the basis of conscious recollection, familiarity, or guessing. Although patients showed overall poorer recognition memory, the beneficial effect of refreshing on long-term memory accuracy and Remember responses was preserved, whereas they derived less benefit in familiarity from seeing an item twice than from refreshing it. These results suggest that although patients may have some difficulty engaging the refresh process, they show significant long-term memory benefits when induced to do so.