An Extension and Clinical Application of the SIMPLE Model to the Free Recall of Repeated and Semantically Related...

A task used in clinical settings to assess memory is a surprise free recall of animal names originally encountered as part of an earlier triadic comparison task. Modeling the free recall is challenging, because learning occurs incidentally, items are presented multiple times, and the items have semantic relationships to each other. To address this challenge, we extend the SIMPLE (Brown et al., 2007) model of memory, which assumes to-be-remembered items are stored as separate logarithmically-compressed temporal traces. The ability to retrieve these traces depends on the acuity of memory probes and the semantic similarity between the items represented by the traces. We apply this model to a real-world clinical data set including healthy controls, people with mild cognitive impairment, and people with Alzheimer's dementia. We find that the groups with memory impairment have worse temporal acuity and make less use of semantic information.