Age-related differences according to the associative deficit and the environmental support hypotheses: an application of the formal charm associative memory model.

UNLABELLED: BACKGROUND/STUDY CONTEXT: According to both the associative deficit hypothesis (ADH; Naveh-Benjamin, 2000 , Journal of Experimental Psychology: Learning, Memory, and Cognition, 26, 1170-1187) and the environmental support hypothesis (ESH; Craik, 1983 , Philosophical Transactions of the Royal Society of London Series B, 302, 354-359), memory decline with aging can be seen as an impairment of the self-initiated associative memory processes such that supportive encoding and/or retrieval can reduce age-related differences. A formalization of relationships between the ADH and ESH was investigated using the distributed memory model "CHARM" (Composite Holographic Associative Recall-Recognition Model; Metcalfe, 1982 , Psychological Review, 89, 627-661; Metcalfe, 1991 , Psychological Review, 98, 529-543). METHODS: Empirical data were collected in young and elderly participants on cued recall and recognition tests according to both the level of processing (LOP: phonetic vs. semantic tasks) and the self-generated cueing (elaboration effect: provided vs. self-generated cue) manipulation. These data were compared with those from CHARM simulations that were designed to evaluate the impact of deteriorated associative processes (i.e., ADH) and the role of LOP and elaboration effects (i.e., ESH) in memory performance. RESULTS: The simulated data were largely consistent with the empirical data, showing that the impairment of associative processes in the CHARM model was accompanied by an increased need for environmental support at encoding (interaction between age, LOP, and elaboration) to reduce memory decline in cued recall tasks, which is somewhat observed in the recognition scores. CONCLUSION: The overall results from CHARM simulations are in accordance with both the ADH and ESH hypotheses and provide discussion on the formal connections between these two main aging explanations.

Virtual/Real transfer of spatial learning: impact of activity according to the retention delay.

Within the framework of cognitive rehabilitation using virtual reality (VR), one of the major challenges is to study beforehand the effectiveness of the virtual-real transfer of learning and to define cognitive aids. The aim of this experiment was to verify if, after learning spatial knowledge (i.e., a route) in VR, performances can be transferred to reality, then maintained in real time, and improved with the aid of an active navigation (i.e., using a joystick). Ninety student volunteers from the University of Bordeaux 2 (45 men and 45 women) participated in the experiment. The virtual environment (VE) used for learning was a replica of an area of Bordeaux. The factors tested were retention delay (Immediate vs. 48 hours) and type of navigation (Passive virtual vs. Active virtual vs. Real), using three recall tasks: wayfinding, freehand sketch and photograph classification. Our results showed that the virtual-real transfer was not degraded by a retention delay of 48 hours and that active navigation allowed performances to be optimized.

Performance on a semantic verbal fluency task across time: dissociation between clustering, switching, and categorical exploitation processes.

The aims of this study were to investigate semantic retrieval processes and errors across time during a semantic fluency task and to specify their components (i.e., executive vs. semantic). To do so, we analyzed the productions of 50 healthy participants (using the "supermarket" fluency task). The scores were compared before and after a 30-s interval. Across time, the results showed a decrease in the number of words produced and hard switching. Cluster switching and the number of intrusions remained constant, while clustering, and both the number of exemplars and repetitions increased. These results are discussed in terms of a progressive involvement of a semantic cognitive strategy of retrieval.