Forgetting as the friend of learning: implications for teaching and self-regulated learning.

One of the "important peculiarities" of human learning (Bjork RA and Bjork EL. , 1992, p. 35-67) is that certain conditions that produce forgetting-that is, impair access to some to-be-learned information studied earlier-also enhance the learning of that information when it is restudied. Such conditions include changing the environmental context from when some to-be-learned material is studied to when that material is restudied; increasing the delay from when something is studied to when it is tested or restudied; and interleaving, rather than blocking, the study or practice of the components of to-be-learned knowledge or skills. In this paper, we provide some conjectures as to why conditions that produce forgetting can also enable learning, and why a misunderstanding of this peculiarity of how humans learn can result in nonoptimal teaching and self-regulated learning.