The role of executive function in imagery mnemonics: evidence from multiple sclerosis

The use of imagery in learning and memory involves metacognitive skills that seem to depend upon executive function as well as motivational mechanisms. This implies that the efficacy of imagery mnemonics should be impaired in neurological patients who show either executive dysfunction or affective disorders. This hypothesis was tested in patients with multiple sclerosis. Imagery instructions led to improved recall in three different tasks, although experimenter-generated imagery proved to be more effective than subject-generated imagery and there was little evidence that patients maintained the use of imagery mnemonics on follow-up testing. Three other tasks defined a unitary trait of executive processing efficiency, and this was significantly correlated with the benefit obtained from the use of the Method of Loci in a free-recall tasks, but not with the benefit gained from other imagery mnemonics. The patients' scores, on a widely used depression inventory, were not significantly correlated with the benefit obtained from the use of imagery mnemonics. Nonetheless, it is concluded that executive processing capacity determines the benefit that is derived from the use of more complex forms of imagery mnemonic in verbal-learning tasks.