Factors that influence skill decay and retention: A quantitative review and analysis

This article presents a review of the skill retention and skill decay literature that focuses on factors that influence the loss of trained skills or knowledge over extended periods of nonuse. Meta-analytic techniques were applied to a total of 189 independent data points extracted from 53 articles. Results indicate that there is substantial skill loss with nonpractice or nonuse, with the amount of skill loss ranging from an effect size (d) of -0.01 immediately after training to a d of -1.4 after more than 365 days of nonuse. Most of the study's hypotheses for moderators were supported. Physical, natural, and speed-based tasks were less susceptible to skill loss than cognitive, artificial, and accuracy-based tasks. Additionally, certain methodological variables, such as using recognition tests, using similar conditions of retrieval at retention, and using behavioral evaluation criteria, resulted in less skill loss over time. Implications of the results for training and future research are discussed.