Evidence for distinct verbal memory pathologies in severely and mildly disturbed schizophrenics

It is well known that schizophrenics have difficulty in effectively encoding verbal materials into their long-term memories and consequently show a deficit in recall. Recently, orienting tasks were introduced as a method for achieving equivalent to normal encoding and mnemonic organization in schizophrenics; consequently, their deficit in recall disappeared. A detailed review of the literature, however, showed that such effective orienting tasks had only been applied to mildly disturbed schizophrenics (nonchronic, in a good condition). This report presents three experiments which show that more severely disturbed (chronic, hospitalized) schizophrenics, unlike mildly disturbed patients, have memory deficits that cannot be located at the encoding stage. Severely disturbed schizophrenics show (1) a recall deficit, even after effective encoding and mnemonic organization are induced; (2) excessive forgetting over 24- and 48-hour periods; and (3) a recognition memory deficit. These deficits are in addition to their encoding deficit. The use of a matched-tasks check in experiments 2 and 3 suggests that this postencoding deficit is a differential deficit and does not is a differential deficit and does not simply reflect the schizophrenic generalized deficit. Theoretical implications, also supported by the use of various organizational indices (e.g., clustering, hierarchical clustering schemes, and hierarchical grouping analysis), are discussed.