This research will investigate the effect of various types of interventions on the longevity of knowledge. One investigation will determine the individual and joint effects of the number of training sessions and of the interval between training sessions on retention of foreign language vocabulary over a period of several years. Other investigations will focus on the maintenance of access to marginal semantic memory content. Such information is reliably identified on tests of recognition, but it is recalled only some of the time; success or failure of an attempt to recall this sort of information depends upon momentary context conditions. The goals of this research are to establish the effects of interventions that either decrease the probability of losing access to marginal memory targets that are momentarily not accessible (preventive maintenance) or re-establish access to targets that are momentarily not accessible (corrective maintenance). These investigations will establish the half-life of several types of preventive and corrective interventions for several types of memory content for young and old adults. Another investigation will explore the possibility of extending the life-span of knowledge acquired in a statistics course by increased spacing of training sessions and by computer-aided instruction. This research can provide the basis for effective schedules and types of interventions designed to assure continuing access to knowledge acquired in schools. The research is also relevant to the formulation of guidelines for the maintenance of professional expertise in various domains of public interest.
