On the cognitive processes mediating intentional memory updating
In list-method directed forgetting (LMDF), cuing people to forget previously studied information and to encode new material instead facilitates recall of the new material (postcue enhancement) but reduces recall of the previously studied information (precue forgetting). The first part of this thesis investigated the nature of postcue enhancement, with Experiments 1A-1C finding that postcue enhancement is accompanied with decreased response latencies. Because response latency is a sensitive
... of participants' mental search set, this finding suggests that postcue enhancement arises due to a more focused memory search. In addition, response latency analysis suggested that such retrieval processes are not only crucial regarding postcue enhancement, but also improve memory of new material when previously studied material is tested prior to encoding of the new material (Experiment 2) or when a context change takes place prior to encoding of the new material (Experiment 3). The second part of this thesis examined the mechanisms underlying precue forgetting by testing whether people can selectively forget only part of the previously studied information while keeping in mind the remaining information. To this end, selectivity in LMDF was examined for two different study formats in Experiment 4: relevant and irrelevant precue items were either presented alternatingly or blocked. Selectivity arose for both study formats, which is consistent with an inhibitory account of precue forgetting. I finally argue that the present data affirm and substantiate a recent LMDF account that attributes precue forgetting to such an inhibitory mechanism and postcue enhancement to a combination of encoding and retrieval processes.