Differential effects of list strength on recollection and familiarity.

Numerous studies have found a null list strength effect (LSE) for recognition sensitivity: Strengthening memory traces associated with some studied items does not impair recognition of nonstrengthened studied items. In Experiment 1, the author found a LSE using receiver operating characteristic-based measures of recognition sensitivity. To account for the discrepancy between this and prior research, the author (a) argues that a LSE occurs for recollection but not for discrimination based on familiarity, and (b) presents self-report data consistent with this hypothesis. Experiment 2 tested the dual-process hypothesis more directly, using switched-plurality (SP) lures to isolate the contribution of recollection. There was a significant LSE for comparisons involving SP lures; the LSE for discrimination of studied items and nominally unrelated lures (which can be supported by familiarity) was not significant.