Confusion between silent and overt reading in schizophrenia

The present study was aimed at investigating whether schizophrenic patients are impaired in monitoring their own speech. In particular, we attempted t o assess their ability to discriminate between overt and covert speech in a reading task, in order to verify whether they can correctly recollect the modality in which an internally generated action is produced. Subjects were asked to read either silently or aloud, items from a list of words. After a delay of 5 min, they were required to indicate in a new list which words had been read previously (either silently or overtly), or had never been pr esented during the reading task. With respect to normal controls, schizophr enic patients showed a significant bias to report that they had read aloud words which they had actually read silently, or which were absent during th e reading task. The results are discussed in relation to recent neuroimagin g studies on inner and overt speech in hallucinating schizophrenic patients . Our data favour the hypothesis that the inability to correctly discrimina te between inner and overt speech may play a role in the onset of schizophr enic hallucinations. (C) 2000 Elsevier Science B.V. All rights reserved.