Atypical meta-memory evaluation strategy in schizophrenia patients

Abstract

Background: Previous research has reported that patients with schizophrenia would regard false memories with higher confidence, and this meta-memory deficit was suggested as a neurocognitive marker of schizophrenia. However, how schizophrenia patients determine their memory decision confidence has received scant consideration. This study, therefore, aimed to characterize the extent to which meta-memory evaluation strategy differs between schizophrenia patients and healthy individuals, and how such difference contributes to the patients' meta-memory performance.

Methods: 27 schizophrenia patients and 28 matched healthy controls performed a temporal-order judgement (TOJ) task, in which they judged which movie frame occurred earlier in an encoded video, and then made retrospective confidence rating. Mixed effect regression models were performed to assess the between-group metacognitive evaluation strategy difference and its relationship to clinical symptoms.

Results: Compared to the control group, the patients' confidence ratings were correlated more with the recent confidence history and less with the TOJ-related evidence. The degree of dependence on recent history of confidence was negatively correlated with the severity of positive symptoms. Furthermore, by controlling for the first-order TOJ performance, we observed that the patients discriminated correct memory decisions from the incorrect ones as accurately as the controls.

Conclusion: The present investigation revealed that schizophrenia patients tend to use more heuristics in making meta-memory evaluations, and such atypical strategy is related to their clinical symptoms. This study provides new insights into how schizophrenia patients perform meta-memory processes. Future research could consider examining such metacognitive deficits in light of other cognitive domains in psychosis.

Keywords: Confidence; False memory; Meta-memory; Schizophrenia; Serial dependence.

Fig. 1

Procedure of Session 1. The procedure of Session 2 and 3 were identical with Session 1 except that there were no video viewing and retention delay periods.

Fig. 2

Scz patients and healthy controls' TOJ accuracy (A); and mean confidence in correct and incorrect TOJ response (B) in both forward-displayed (FW) and reversed-displayed (RV) conditions.

Fig. 3

Regression model predicting TOJ performance confidence within a given trial as a function of decision correctness (A), reaction time (B), and recent history of confidence (i.e., the average of 5-trial-back ratings; C) for both schizophrenia and healthy control groups. Error bars in A, and the light grey areas in B–C, represent the 95% confidence interval of the estimation. The values of all non-binary variables were standardized using z-scores.

Fig. 4

Modulation effects of positive (P; A), negative (N; B), and general (G; C) symptoms on the relationship between trial-by-trial confidence and recent history of confidence. Values of all the non-binary variables, including the total score of each symptom type measured from the PANSS scale, were standardized by z-scores. Regarding the P/N/G scores, “0” is the mean score, while “1” and “-1” refer to scores that are 1 standard deviation above and below the mean, respectively. The light grey areas represent the 95% confidence interval of the estimation.