Understanding Prospective Memory: Baselines for a Study on Memory Deficits in Epilepsy

Abstract

Forgetting to do things can be disruptive to our lives and can often land the best of us in embarrassing or irritating situations. Sometimes the consequences of a failure of Prospective Memory (PM) can be much more serious: It is potentially very dangerous for a patient with epilepsy to forget to take their medication. In this study the multiprocess model of PM (McDaniel & Einstein, 2000) is exploited to help explore the possibility of the existence of a dissociation between patients with temporal lobe epilepsy (TLE) and patients with frontal lobe epilepsy (FLE) in their ability to perform PM tasks. This is based on a hypothesis that TLE patients and FLE patients may show a dissociation in impaired memory and executive dysfunction, respectively. Healthy participants were tested in one of two conditions: One manipulated to exert a spontaneous retrieval process; and one manipulated to exert a continual-monitoring process. The effects of reduced memory capacity (mimicking TLE) and divided attention (mimicking FLE) on PM performance were investigated by adding extra (memory or attentional) loads. Participants also filled in a ‘Remembering to Do Things’ questionnaire to give a subjective evaluation of PM. Neither, reduced memory capacity, or divided attention was found to affect prospective remembering in either condition. Performance on the PM Task alone was better by those in the spontaneous retrieval condition. Reaction times for the ongoing lexical decision task were faster for those in the spontaneous retrieval condition when the PM Task was introduced; and even faster with the additional memory load. Introduction of the PM task slowed the reaction speeds of those in the continual-monitoring condition. The concurrent attentional task slowed reaction speeds for participants in both conditions. The results obtained have helped to illuminate the processes that may support prospective remembering and provide a valuable baseline for future studies on prospective remembering in patients with epilepsy.