Voluntary forgetting before and after learning has been accomplished

Two experiments, in which voluntary forgetting was measured, are reported. In both experiments, lists of randomly mixed syllables and numbers were projected on a screen, and Ss were instructed before projection which part of the lists to remember or to forget. In the first experiment, the syllables were cued as items to be forgotten in one group, and to be remembered in the other one. At the end of the projection, Ss were instructed to recall freely only the syllables. For the former group, this was an unexpected test. The same list was projected for different groups: one, three, five, seven, and fourteen times, with new randomly mixed items each time. Syllable recall increased with an increase of times of projection of the list in the second group, but not in the first one. Recall of syllables in the first group was, however, above the chance level. These results were best interpreted by assuming a voluntary forgetting mechanism, which operates after the verbal items leave the short term store. The second experiment, a variation of the first, was designed to find the locus of voluntary forgetting mechanisms. The question is whether Ss can voluntarily forget syllables only before they are learned, or also after learning has already taken place. Voluntary forgetting after learning has been achieved was found to be ineffective. These results tend to support the hypothesis that voluntary forgetting processes do not operate in the long-term store and that Ss can block the transmission of to be forgotten items from the short-term store to the long-term store.