Levels-of-processing effect on word recognition in schizophrenia

Abstract

Background: Individuals with schizophrenia have difficulty organizing words semantically to facilitate encoding. This is commonly attributed to organizational rather than semantic processing limitations. By requiring participants to classify and encode words on either a shallow (e.g., uppercase/lowercase) or deep level (e.g., concrete/abstract), the levels-of-processing paradigm eliminates the need to generate organizational strategies.

Methods: This paradigm was administered to 30 patients with schizophrenia and 30 healthy comparison subjects to test whether providing a strategy would improve patient performance.

Results: Word classification during shallow and deep encoding was slower and less accurate in patients. Patients also responded slowly during recognition testing and maintained a more conservative response bias following deep encoding; however, both groups showed a robust levels-of-processing effect on recognition accuracy, with unimpaired patient performance following both shallow and deep encoding.

Conclusions: This normal levels-of-processing effect in the patient sample suggests that semantic processing is sufficiently intact for patients to benefit from organizational cues. Memory remediation efforts may therefore be most successful if they focus on teaching patients to form organizational strategies during initial encoding.

Figure 1

Mean (±SEM) recognition discriminability for 30 healthy comparison subjects (solid line) and 30 patients with schizophrenia (dotted line).

Figure 2

Mean (±SEM) recognition response bias for 30 healthy comparison subjects (solid line) and 30 patients with schizophrenia (dotted line).

Figure 3

Mean (±SEM) reaction time (in milliseconds) for 30 healthy comparison subjects (solid line) and 30 patients with schizophrenia (dotted line).