Age Effects in Implicit Memory: The Role of Response Competition Induced by Relative Word Frequency.

BACKGROUND/STUDY CONTEXT: This study examined the effect of age and response competition on implicit memory performance. METHODS: Younger and older adults studied high- and low-frequency words and took a word stem completion test that could be completed with multiple solutions. To manipulate response competition, the test list consisted of word stems that could be completed with target low-frequency words, as well as multiple other solutions with higher frequencies than the target (the high response competition condition) and word stems that could be completed with target high-frequency words, as well as multiple other solutions with lower frequencies than the target (the low response competition condition). RESULTS: Relative to younger adults, older adults showed reduced levels of priming only under conditions of high response competition (low-frequency targets with high-frequency competitors). CONCLUSION: In support of a response competition mechanism, older adults were more likely to complete stems with nonstudied high-frequency solutions than were younger adults. Results demonstrate that older adults have reduced priming compared with younger adults under some conditions of high response competition.

Examining the response competition hypothesis of age effects in implicit memory.

Age reductions in priming have been explained by differences in processing demands across implicit memory tests. According to one hypothesis, older adults show reduced priming relative to younger adults on implicit tests that require production of a response because these tests typically allow for response competition. In contrast, older adults do not show reductions in priming on identification tests that contain little response competition. The following experiments tested the specific role of response competition in mediating age effects in implicit memory. In Experiment 1, younger and older adults studied a list of words and were then given an implicit test of word stem completion. They studied a second list of words and were given an implicit test of general knowledge. Each implicit test contained items with unique solutions (the low response competition condition) and items with multiple solutions (the high response competition condition). In Experiment 2, younger and older adults were given explicit versions of the word stem completion and the general knowledge tests. Results showed an effect of age on explicit memory (Experiment 2), but no effect of age or response competition on priming (Experiment 1). Results are inconsistent with the theory that response competition leads to age effects on production tests of implicit memory.

The picture superiority effect in conceptual implicit memory: a conceptual distinctiveness hypothesis.

According to leading theories, the picture superiority effect is driven by conceptual processing, yet this effect has been difficult to obtain using conceptual implicit memory tests. We hypothesized that the picture superiority effect results from conceptual processing of a picture's distinctive features rather than a picture's semantic features. To test this hypothesis, we used 2 conceptual implicit general knowledge tests; one cued conceptually distinctive features (e.g., "What animal has large eyes?") and the other cued semantic features (e.g., "What animal is the figurehead of Tootsie Roll?"). Results showed a picture superiority effect only on the conceptual test using distinctive cues, supporting our hypothesis that this effect is mediated by conceptual processing of a picture's distinctive features.

States of awareness across multiple memory tasks: obtaining a "pure" measure of conscious recollection.

Four experiments were conducted to examine the nature of recollective experience across different explicit memory tests. Experiments 1 and 2 showed that the proportion of retrieved items that were given Remember responses were equivalent across free recall, category cued recall, category plus letter cued recall, and recognition memory tests unlike the result reported by Tulving [Can. Psychol. 26 (1985) 1]. Experiments 3 and 4 revealed that Remember judgments are influenced by both conceptual and perceptual variables not only in the recognition task but in other explicit memory tasks as well. Taken together, the empirical evidence from this study demonstrates that explicit memory performance is accompanied by different states of awareness not only in recognition but also across other memory tasks including free recall.

Distinguishing states of awareness from confidence during retrieval: evidence from amnesia.

Two experiments were conducted to determine whether recollective experience is distinguishable from confidence. In Experiment 1, we tested college participants in a within-subjects design and replicated Gardiner and Java's (1990) findings from a between-subjects design. We observed higher remember judgments for words than for nonwords, but higher know judgments for nonwords than for words. For confidence judgments, we obtained greater sure than unsure responses for both words and nonwords. In Experiment 2, we tested amnesic participants and matched control participants. Control participants produced the same pattern of results as college participants, but the results of amnesic participants diverged in an important way. For confidence judgments, the amnesic participants, like the control and college participants, made more sure than unsure judgments to both words and nonwords. But for recollective judgments, amnesic participants did not produce the crossover interaction for words and nonwords. This striking difference between the performance of memory-intact and amnesic participants demonstrates that recollective judgments and confidence that accompany retrieval are not isomorphic psychological experiences.