Destructive effects of "forget" instructions

In two experiments, participants were given three lists of words to study and were told to (1) remember all three lists, (2) forget the first list immediately after studying it but try to remember the other two lists, or (3) forget the middle list immediately after studying it but try to remember the first and the last lists. In Experiment 1, unrelated word lists were used, whereas Experiment 2 replicated Experiment 1 with categorical lists. The results from both experiments showed that forgetting the middle list leads also to recall decrement for the first list, which was not intended for forgetting. The results are discussed in terms of the contextual change hypothesis of directed forgetting.