Simple Measurement Models for Complex Working-Memory Tasks

We introduce a framework for simple measurement models for working memory, and apply it to complex-span and memory-updating tasks. Memory Measurement Models (M-3) use the frequency distribution across response categories to measure continuous memory strength along 2 dimensions: Memory for individual elements, potentially relying on persistent activation of unified representations, and memory for relations, relying on temporary bindings. Experiment 1 provides evidence for the validity of the parameters measuring these two dimensions of strength. The effects of experimental manipulations on these 2 dimensions can be captured by additional model parameters that reflect hypothetical processes affecting memory. Across five further experiments we illustrate how M3 can be used to measure 3 such processes: The continued strengthening of memory representations during the retention interval (extended encoding), the dampening of encoding of irrelevant information (filtering), and the removal of irrelevant information from memory. In one experiment we compare young and old adults on complex-span tasks and working memory updating. In both paradigms, old adults showed impaired memory for relations but no impairment in memory for individual elements. There was partial evidence for age differences in extended encoding and removal; there were no age differences in filtering. We suggest that M3 offer a computationally efficient approach to identifying memory processes.