Dilution as a Model of Long-Term Forgetting

This article presents a model of long term forgetting based on 3 ideas: (a) Memory for a stimulus can be described by a population of accessible traces; (b) probability of retrieval after a delay is predicted by the proportion of traces in this population that will be defined as correct if sampled; and (c) this population is diluted over time by null traces that, if accessed, block retrieval. Dilution is modeled as a linear function of time and outcome of accessing memories by their temporal organization. The model is applied to 5 published experiments studying forgetting in cued recall, 4 recognition experiments, and I using savings methods. The model specifies the different form of the retention function in each case well and provides a principled explanation for some puzzling characteristics of forgetting without recourse to mechanisms such as decay or consolidation.