Providing support for distinctive processing: the isolation effect in young and older adults

The isolation paradigm is the classic method for studying the effects of distinctiveness on memory (Hunt, 1995). Previous studies using the isolation paradigm with older adults (Bireta, Suprenant, & Neath, 2008; Cimbalo & Brink, 1982; Geraci, McDaniel, Manzano, & Roediger (2009); Vitali et al., 2006) placed the isolated items late in the study list. The current experiments, which are the first to investigate the isolation effect in young and older adults when the isolated item occurs early in the list, were motivated by a new framework for understanding age-related differences in the beneficial effects of distinctive processing. The framework, which is motivated by Hunt's (2006) discussion of distinctiveness and Craik's (1986) environmental support view, proposes that when contextual support is provided for the processing of both the difference and similarity components, older adults are more likely to show beneficial effects of distinctiveness. In Experiment 1, young adults showed both early and late isolation effects, while older adults showed only a late isolation effect. In the first experiment the isolated item was the word "table" in a list of fish names. In Experiment 2, the contrast between the isolated item and background items was increased by isolating numbers in a list of words. In the second experiment older adults, as well as young adults, showed an early isolation effect.