Attentional limits in memory retrieval-revisited

Carrier and Pashler (1995) concluded-based on locus-of-slack dual-task methodology-that memory retrieval was subject to a central bottleneck. However, this conclusion conflicts with evidence from other lines of research suggesting that memory retrieval proceeds autonomously, in parallel with many other mental processes. In the present experiments we explored the possibility that Carrier and Pashler's conclusions were distorted by use of an experimental method unfavorable to parallel memory retrieval. New locus-of-slack experiments were performed that encouraged parallel memory retrieval strategies with instructions and feedback, along with the use of "preferred" stimulus-response modality mappings. Results from two psychological refractory period experiments showed that the effect of Task 2 recognition difficulty was consistently absorbed into cognitive slack, with both word and picture recognition. We conclude that the memory retrieval stage of recognition tasks can proceed in parallel with central operations of another task, at least under favorable conditions. Our new findings bring results from dual-task locus-of-slack methodology into agreement with other evidence that memory retrieval is not subject to severe, generic central resource limitations.