Healthy ageing reduces the precision of episodic memory retrieval.

Episodic memory declines with older age, but it is unresolved whether this decline reflects reduced probability of successfully retrieving information from memory, or decreased precision of the retrieved information. Here, we used continuous measures of episodic memory retrieval in combination with computational mixture modeling of participants' retrieval errors to distinguish between these two potential accounts of age-related memory deficits. In three experiments, young and older participants encoded stimulus displays consisting of everyday objects varying along different perceptual features (e.g., location, color and orientation) in a circular space. At test, participants recreated the features of studied objects using a continuous response dial. Across all 3 experiments, we observed significant age-related declines in the precision of episodic memory retrieval, whereas significant age differences in retrieval success were limited to the most challenging task condition. Reductions in mnemonic precision were evident across different object features retained in long-term memory and persisted after controlling for age-related decreases in the fidelity of perception and working memory. The findings highlight impoverished precision of memory representations as one factor contributing to age-related episodic memory loss and suggest that the cognitive and neural changes associated with older age may differentially affect distinct aspects of episodic retrieval. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Flexible updating of dynamic knowledge structures.

Schemas are knowledge structures that allow us to make efficient judgments about the world without the cost of memorizing every detail of previous experiences. It has long been known that schemas can enhance long-term memory for related information. The usefulness of schemas, however, critically depends on their adaptability: how flexibly a schema can be updated according to changing environmental conditions. Prior consolidation of a schema supports new learning of schema-consistent information. Yet, the effect of consolidation on inconsistent information, and how schemas may be subsequently updated, are not well understood. It is difficult to track the dynamic updating of knowledge structures with traditional memory measures. Here, using a continuous-report paradigm, we were able to show that schematization increases incrementally with consolidation and that the strength with which schemas are initially established predicts schema-guided responding in a later test. Critically, schema updating in response to inconsistent information was more pronounced in a group which was given time to consolidate compared to a group that was not given time to consolidate. Importantly, the later group reverted back to the no longer relevant schema, indicating that systematic bias towards old information, rather than increased forgetting, underlies reduced memory for schema-inconsistent information.