Age and Inhibition: The Retrieval of Situation Models

We present a test of whether age-related differences in the management of interference during memory retrieval can be explained, at least in part, by decreased inhibitory mechanisms in older adults. We conducted this test by measuring the ease of retrieval of situation model representations that were sources of interference on the preceding trial but that contained the target information for the current trial. Prior research has shown that situation model retrieval under these conditions exhibits inhibition relative to an unrelated control. This effect was replicated in the current study for younger but not older adults; at the same time, the older adults showed greater overall retrieval interference than the younger adults. This pattern is consistent with the idea that there are declines in inhibitory processing in older adults, and that this applies to memory retrieval. T HE study reported here reexamines data from an earlierreport of age differences in long-term memory retrieval (Radvansky, Zacks, & Hasher, 1996) using a fan effect para-digm (Anderson, 1974). In the current study we elaborate on these findings by an assessment of retrieval inhibition (Radvansky, 1999). In the fan effect paradigm, people memo-rize a set of facts and are then given a speeded recognition test. The central finding is that, as the number of associations with a concept in the study list increases, there is an increase in response time and error rate. This increase is even greater for older than for younger adults (Radvansky et al.), an effect attributed to reduced inhibitory abilities associated with aging (Hasher & Zacks, 1988; Hasher, Zacks & May, 1999; Zacks & Hasher, 1994). The speculation offered in the earlier report was that older adults have more trouble suppressing the related but irrelevant associations learned in the context of the study. The current study provides a direct test of this speculation. Other work on the fan effect has suggested that people can create situation models of the information in the stud