Long-term effects of testing on the recall of nontested materials

The isolation paradigm is a staple in the study of distinctiveness and memory. Isolated items are better remembered than non-isolated controls, and the standard interpretation of this effect is that subjective experience of salience recruits extraordinary processing to the isolated item. This interpretation is at odds with data showing an isolation effect when the isolate is not perceived as salient (e.g., von Restorff, 1933). All available research on the early isolation effect has tested memory after a relatively short retention interval. Perhaps the effect of salience on memory in the isolation paradigm would be revealed following longer retention intervals. The experiment reported here examines the effect of isolation following a 48-hour retention interval when the isolate evokes an experience of salience compared to when the isolate does not evoke that reaction. The isolation effect was substantial after the 48-hour delay but equally so for early and late isolation. Salience appears to have nothing to do with the memory processes even at the longer retention intervals.