Examining the effect size and duration of retrieval-induced facilitation

Under certain conditions, the retrieval of some information can increase the recall of other information, a phenomenon known as retrieval-induced facilitation. Chan (Journal of Memory and Language 61:153-170, 2009) proposed two moderating factors to account for why retrieval causes facilitation in some situations and forgetting in others: (1) integration at the time of encoding and (2) the delay between retrieval practice and final test. Chan found a 9-11% facilitation effect when the materials were well integrated and the final test occurred after a 24-h delay. Two sets of experiments sought to replicate and extend Chan's study by examining retrieval-induced facilitation not only following a 24-h delay but after longer delays (i.e., 1 or 2 weeks). A meta-analysis including these replications and the original experiments was also conducted. The results provide additional evidence of retrieval-induced facilitation, with no evidence that the effect varies as a function of the final delay. However, the size of the effect was found to be somewhat smaller than previously observed.