Removing irrelevant information from working memory: A cognitive aging study with the modified Sternberg task

Two experiments with a modified Sternberg recognition task explored the abi lity of young and old adults to remove irrelevant information from working memory. The task involved 2 memory sets, 1 of which was later cued as irrel evant. The recognition probe was presented at a variable time after the cue . Two indicators of inhibition, the setsize effect of the irrelevant set an d the reaction time cost of intrusion probes (i.e., negative probes present in the irrelevant list), were dissociated. Irrelevant setsize effects last ed less than 1 s after the cue and did not differ between old and young adu lts. Intrusion costs lasted up to 5 s and were disproportionally large for old adults. With the additional requirement to remember both lists until af ter the probe, young adults' intrusion costs in Experiment 2 were equivalen t to those of old adults in Experiment 1, but the setsize effects of the ir relevant set was larger. The results are compatible with a dual-process mod el of recognition in combination with a working-memory model distinguishing the focus of attention from the activated portion of long-term memory.