Signal detection analysis of short-term recall in schizophrenia

Unlike many traditional performance measures, signal detection indices of sensitivity are free of response biases. Signal detection and traditional indices of performance were obtained from a short-term recall task during distractor and neutral conditions for schizophrenic patients and normal subjects. Items in each condition had been matched previously for difficulty and consistency to determine whether diminished recall during distraction represented a true differential deficit. Results showed similar patterns for both types of indices: Normal subjects performed better than patients across both conditions, patients recalled less after presentation of a distractor than during a neutral condition, and normal subjects showed no performance decrement between the two conditions. These findings demonstrated that the differential deficit was due to changes in schizophrenic patients’ sensitivity to stimulus items, not response biases.