Fundamental Law of Memory Recall

Free recall of random lists of words is a standard way to probe human memory. There is no accepted theory that quantitatively predicts the performance in this task. We proposed the associative search process that can be mathematically solved, providing an analytical prediction for the average number of words recalled from a list of an arbitrary length. Previously reported free recall performance depended on experimental details. Since recall could be affected by variability in words acquisition, we designed a protocol where participants performed both recall and recognition trials, using the latter to estimate the number of acquired words. The results closely match theoretical prediction. We conclude that memory recall operates according to a stereotyped search process common to all people.