In three experiments, we examined the mechanisms by which prior experience with proactive interference (PI) diminished its effects. Cued recall tasks conforming to an A-B, A-D paradigm were used to induce PI effects. Experiment 1 showed that reduced PI was not due to a reduction in attention to the source of PI. Experiment 2 revealed that participants' awareness of PI effects on memory performance increased with experience, resulting in a shift in encoding processes. Experiment 3 demonstrated that changes in encoding provided additional support for recollection that further enhanced participants' ability to constrain their retrieval processing to the appropriate source of information at the time of test. These results can be interpreted as showing that experience with PI enhances awareness of its effects and allows individuals to adjust their learning and retrieval strategies to compensate for such effects.Keywords Proactive interference . Metacognition . Sourceconstrained retrieval . Memory training Proactive interference (PI) is a potent source of forgetting. For serial learning, Underwood (1957) reviewed experiments in which the effects of PI were examined and found that the probability of recall decreased dramatically from .80 when there was no preceding list to approximately .20 following 20 preceding lists. Paired-associate learning also shows large effects of PI (for a review, see Anderson & Neely, 1996). The question we ask in this article is whether participants are unaware of the effects of PI during a first encounter with PI but become aware of its effects and successfully implement procedures to diminish those effects during a second encounter with PI. Although the effects of PI are widely known by memory researchers, little has been done to investigate people's ability to diminish its effects. Findings of an ability to adapt learning in ways that diminish the effects of PI are important for gaining a better understanding of the effects of PI and, potentially, hold import for applied purposes.In commonplace situations, people show knowledge of PI effects by taking actions to avoid such effects. For example, in card games, it is common for the dealing of cards to pass around the table, creating the problem of remembering who dealt last so as to decide whose turn it currently is to deal. This problem is typically solved by playing with two decks of cards, with one of the decks being placed in front of the person who is to deal next while the other deck is being dealt. However, rather than being generally aware of effects of PI, such awareness might be restricted to particular situations. For card playing, it is likely that problems produced by PI were discovered as a result of experience in the situation, and only then were steps taken to eliminate its effects. Similarly, combating PI in a list-learning situation might depend on prior experience in the situation of a sort that makes people aware of its effects.To our knowledge, the only investigation of ability to diminish PI as a result of pri...