Effects of repetition on associative recognition in young and older adults: item and associative strengthening

Abstract

Young and older adults studied word pairs and later discriminated studied pairs from various types of foils including recombined word-pairs and foil pairs containing one or two previously unstudied words. We manipulated how many times a specific word pair was repeated (1 or 5) and how many different words were associated with a given word (1 or 5) to tease apart the effects of item familiarity from recollection of the association. Rather than making simple old/new judgments, subjects chose one of five responses: (a) Old-Old (original), (b) Old-Old (rearranged), (c) Old-New, (d) New-Old, (e) New-New. Veridical recollection was impaired in old age in all memory conditions. There was evidence for a higher rate of false recollection of rearranged pairs following exact repetition of study pairs in older but not younger adults. In contrast, older adults were not more susceptible to interference than young adults when one or both words of the pair had multiple competing associates. Older adults were just as able as young adults to use item familiarity to recognize which word of a foil was old. This pattern suggests that recollection problems in advanced age are because of a deficit in older adults' formation or retrieval of new associations in memory. A modeling simulation provided good fits to these data and offers a mechanistic explanation based on an age-related reduction of working memory.

Figure 1

Conceptual illustration of how items (circles) and associations (ovals) are represented and linked in memory in response to the various intact, rearranged, item, and novel test probes to studied word pairs as a result of our experimental manipulations of repetition (1 or 5 presentations) and interference (1 or 5 associations). The filled items in gray depict the words that are activated during test probe presentation. Line thickness denotes item and associative strength resulting from the experimental manipulation of repetition and interference during encoding.

Figure 2

Panel A. Young (closed symbol) and Older adult (open symbols) proportions of ‘Old-Old (original)’ hit responses to intact word pairs and ‘Old-Old (original)’ false alarm responses to rearranged word pairs as a function of increasing associative interference (Rep ×5, Fan 1-1, [Fan 1-5, Fan 5-1], Fan 5-5). Panel B. Mean d′ statistic as a function of associative interference. The error bars are standard errors of the mean.

Figure 3

Overview of model fits to the young (closed symbol) and older adult (open symbol) data across the range of response proportions (unspecified) expressed as a function of model prediction vs. actual data. The diagonal signifies a perfect fit of the model to the data; deviations above or below the diagonal reflect an under-fitting or over-fitting of the data, respectively. Refer to Tables 4 and 5 for a full account of the model fits specified by both response and condition.

Appendix Figure

Panel A. Young adult response latencies (mean of medians) for hit responses to intact pairs, novel pairs, rearranged pairs, and item pairs. Panel B. Older adult response latencies (mean of medians) for hit responses to intact pairs, novel pairs, rearranged pairs, and item pairs.