Effects of Age and Divided Attention on Memory Components Derived for the Category Exemplar Generation Task

ABSTRACT

Age differences in memory performances on a conceptually driven task, the category exemplar generation (CEG) test, were investigated. Thirty-six younger adults and 36 healthy older adults studied word lists in full and divided attention conditions. Recall was tested with category names. The process-dissociation procedure was used to derive estimates of controlled and automatic memory. Old-old adults (70–84 years) exhibited poorer conscious recollection than both younger (18–24) and young-old adults (59–69). In contrast, no age differences were found in estimates of automatic memory. For the younger and older adults, the divided encoding manipulation reduced both the consciously controlled and automatic estimates of memory. The results suggest that the few prior findings of age deficits in priming on the CEG may have been an artifact of contamination from conscious retrieval processes. They also indicate that the opportunity for greater semantic processing enhances the conceptual priming of both younger and older adults.

ACKNOWLEDGMENTS

The authors gratefully acknowledge the assistance of Leigh Beglinger for her support in coordinating data collection and members of the Cognitive Aging Research Laboratory for their help in collecting and scoring the data.

Notes

¹ In indirect category exemplar generation studies, participants are presented with exemplars of different categories (e.g., birds or games) and are later asked to generate examples of these categories with no mention being made about the previous study episode. Automatic memory is inferred in these tasks from the enhanced tendency of subjects to complete test items that do not make explicit reference to a past study episode with previously encountered target stimuli (Greene, 1986). This performance facilitation of the previously encountered stimuli is referred to as “priming” (Tulving & Schacter, 1990).

² It should be noted that use of the PDP with the inclusion-exclusion test instructions relies on several assumptions which have been controversial. These assumptions, including the assumption that the processes estimated by C and A are functionally independent, have been debated extensively elsewhere (e.g., Curran & Hintzman, 1995, 1997; Cowan & Stadler, 1996; Dodson & Johnson, 1996; Graf & Komatsu, 1994; Hay & Jacoby, 1996; Hintzman & Curran, 1997; Jacoby et al., 1997a; Jacoby & Shrout, 1997; Jacoby et al., 1997b; Joordens & Merikle, 1993; Mulligan & Hirshman, 1997). It is now clear that assumptions underlying the PDP can be violated (see Jacoby, 1998). Jacoby (1998) has described a set of conditions that are important for meeting the independence assumption, and the assumption that conscious recollection contributes to performance to the same extent under both inclusion and exclusion test instructions. The conditions outlined by Jacoby (1998) include using task instructions that encourage participants to employ a direct-retrieval strategy in both the inclusion and exclusion test conditions. Direct-retrieval instructions encourage participants to exclude items only on the basis of recollection and have been shown to result in equivalent base rates across inclusion and exclusion conditions. Jacoby (1998) has demonstrated that use of an alternate generate/recognize strategy can lead to violations of the PDP's assumptions. Participants in this study were encouraged to use a direct-retrieval strategy and the experimental methodology conformed closely to the conditions described by Jacoby (1998).

³ As an example, lack of finding an interaction between age and the attentional manipulation in previous studies with direct tests could have occurred because in some cases, automatic influences of memory may have contaminated performance on the direct test. That is, many of the studies that failed to find that older adults were disproportionately affected by the divided attention manipulation employed recognition measures (e.g., Light & Prull, 1995, Experiment 2; Park et al., 1986). Unlike recall measures, which are thought to rely mostly on conscious recollection, a portion of recognition testing has been found to be dependent on automatic influences or a familiarity response (Jacoby, 1991; Jacoby et al., 1989; Toth et al., 1992).

⁴ The choice between means of dealing with zero scores in exclusion performance currently remains controversial (see Jacoby et al., 1997; Curran & Hintzman, 1997). Jacoby (1998) advocates selecting stimuli that produce base rates which are sufficiently high to avoid zeros in exclusion conditions.

⁵ The results of an age group by encoding condition ANOVA conducted on the estimate of A prior to removing those participants who scored zero in the exclusion condition, revealed similar results. That is, there was a significant main effect of encoding condition, F(1, 69) = 8.34, MSE = .09, but no significant main effect of group, F = 2.34, and no significant interaction, F < 1.

⁶ For the subgroup of participants who successfully met their digit response goal in the divided attention condition, the results of a 2 (group) × 2 (encoding condition) ANOVA on the estimates of C revealed a main effect of encoding condition, F(1, 38) = 12.70, MSE = .42. There was no significant main effect of age group or age group by encoding condition interaction, F's < 1.3. A similar ANOVA on the estimates of A also revealed only a main effect of encoding condition, F(1, 38) = 3.94, MSE = .05. Furthermore, for the younger adults who successfully met their digit response goal in the divided attention condition, the effect of the attentional manipulation on the estimate of A (A_full = .19; A_div = .14) was much more prominent than that for the entire group.

⁷ The results of an age group (younger vs. young-old) by encoding condition (full and divided) ANOVA on the estimates of C revealed a main effect of encoding condition, F(1, 57) = 27.98, MSE = .68. The main effect of age group and the age group by encoding condition interaction were not significant, F's < 1.9.