How do we perform backward serial recall?

Following Conrad (1965, Journal of Verbal Learning and Verbal Behavior, 4, 161–169) it is often assumed that backward verbal serial recall is performed by repeated forward scans through the list and then recalling the last remaining item. Direct evidence for this peel-off strategy is relatively weak, and there has to date been no examination of its potential role in the recall of spatial sequences. To examine the role of this strategy in both verbal and spatial domains, two experiments examined response output times for forward and backward recall. For spatial span, the pattern of timing was the same in both directions. For digit span, backward recall was considerably slower. This was true whether responses were made by means of manual selection on a keyboard display (Experiment 1) or were spoken (Experiment 2a). Only two of 24 participants showed signs of using a peel-off strategy in spoken backward recall. Peel-off was not a dominant strategy in backward digit recall and there was no indication that it was ever used for spatial stimuli. Most participants reported using a combination of different strategies. In Experiment 2b, four further participants were directly instructed to use a peel-off strategy. The pattern of response times for three of these individuals was similar to the two participants from Experiment 2a previously identified as using peel-off. We conclude that backward recall can be performed using many strategies, but that the peel-off is rarely used spontaneously.