High delusional ideation is associated with false pictorial memory.

BACKGROUND AND OBJECTIVES: To assess the relationship between false memories and schizotypal experiences in healthy volunteers. Previous research has examined a number of schizotypal dimensions and experiences and found a variety of results. Our aim was to determine the specificity of these associations by giving participants a schizotypy measure which tapped positive, negative and disorganised dimensions (O-LIFE) and another which focused on delusional ideation (PDI).

METHODS: A new memory task was used consisting of images of everyday items, separated into categories. At test participants were presented with pictures which had been seen in the study phase, related lures (additional items from the same categories but which were new) and new items which were not from these categories.

RESULTS: Positive correlations were found between scores on the positive dimension of schizotypy/delusional ideation and proportion of false memories. Moreover, these participants also had a greater tendency to respond with the highest confidence old response, regardless of the status of the item. No significant correlations were found with the other dimensions of schizotypy.

LIMITATIONS: The confidence finding differs somewhat from previous research, which has found more confidence in memory errors and less confidence in correct responses in schizophrenia. It is unclear the reason(s) for this discrepancy.

CONCLUSIONS: Increased false memory is associated with the positive dimension of schizotypy and delusional ideation and not the disorganised or negative dimensions. Furthermore, our results suggest that those high in positive schizotypy/delusional ideation require less evidence before they are willing to call an item old.