Prior knowledge biases episodic memory by filling in the gaps in imprecise memories: Simulating aging effects in...

Episodic memories are consistently biased by prior knowledge in the form of schemas (e.g., where objects typically are). Rational memory reconstruction models propose that this results from the strategic recruitment of schemas at retrieval when memory traces are imprecise. We recently proposed that these models can also account for the increase in schema bias with aging: Aging reduces memory precision, thereby increasing schema usage. However, causal evidence that underlying memory imprecision increases schema bias is lacking, which is a critical gap for reconstruction theories and for our extension to aging. To examine the effect of underlying memory precision on schema bias, we manipulated memory in younger adults. In two studies (n = 423), participants searched for objects in schema-congruent and incongruent scene locations; each scene was presented either three times (3×) or once (1×). During later retrieval, participants saw the background scenes and provided scene recognition responses indexing memory availability for the episode, and provided object location recall responses indexing memory precision. We found that memory precision was lower for 1× than 3× scenes, even when memory for the episode was available (i.e., participants reported confident recollection). Critically, schema bias of object recall was higher for 1× than 3× scenes, even for recollected scenes. In Experiment 2, metacognitive assessments of memory precision mediated the effects of repetition on schema bias. Therefore, weakening underlying memory precision increased schema bias, which successfully simulates prior aging effects and supports the proposal that rational reconstruction processes drive schema bias of memory both in general and in aging.