Abstract
We first overview the available literature on the effects of retention interval in prospective memory, suggesting that the retention interval itself is not an important variable: More important is the nature of the intervening activities. In a prospective memory experiment, young and older subjects were asked to press on a space bar every three minutes whilst watching either an involving or boring film. With an involving movie, older subjects arc significantly slower on the prospective memory task. The anxiety of the subjects did not change the pattern of findings. Although young subjects recall more (retrospectively) after an involving movie than after a boring movie, their speed of responding on the prospective task is unaffected by the nature of the movie. The findings are explained in terms of an age-decline in processing resources as well as a reduced inhibitory efficiency in the elderly, emphasizing the importance of concurrent activities as an interfering factor in a prospective task.