Spacing repetitions and solving problems are not the same

Recall of items given spaced repetitions is generally superior to recall of items given immediate repetitions. L. L. Jacoby (Journal of Verbal Learning and Verbal Behavior, 1978, 17, 649-667) has proposed that this spacing effect can be accounted for by the distinction between problem solving and remembering. On an immediate repetition any encoding processes and problem-solving operations used on the first presentation can be remembered. On a spaced repetition the operations must be reemployed, thus enhancing the strength of the mnemonic representation of the event. This hypothesis was tested by factorially combining spacing of repetitions, necessity for problem solving at the second presentation, and type of memory test. Requiring problem solving on second presentations did attentuate the spacing effect on a recognition test, but contrary to the hypothesis, no attenuation was found on a recall test.