Aging and IQ effects on associative recognition and priming in item recognition

Two ways to examine memory for associative relationships between pairs of words were tested: an explicit method, associative recognition, and an implicit method, priming in item recognition. In an experiment with both kinds of tests, participants were asked to learn pairs of words. For the explicit test, participants were asked to decide whether two words of a test pair had been studied in the same or different pairs. For the implicit test, participants were asked to decide whether single words had or had not been among the studied pairs. Some test words were immediately preceded in the test list by the other word of the same pair and some by a word from a different pair. Diffusion model (Ratcliff, 1978; Ratcliff & McKoon, 2008) analyses were carried out for both tasks for college-age participants, 60-74 year olds, and 75-90 year olds, and for higher- and lower-IQ participants, in order to compare the two measures of associative strength. Results showed parallel behavior of drift rates for associative recognition and priming across ages and across IQ, indicating that they are based, at least to some degree, on the same information in memory.

Modeling and Estimating Recall Processing Capacity: Sensitivity and Diagnostic Utility in Application to Mild Cognitive Impairment

We investigate the potential for using latency-based measures of retrieval processing capacity to assess changes in perfomance specific to individuals with mild cognitive impairment (MCI), a reliable precursor state to Alzheimer's Disease. Use of these capacity measures is motivated in part by exploration of the effects of atrophy on a computational model of a basic hippocampal circuit. We use this model to suggest that capacity may be a more sensitive indicator of undelying atrophy than speed of processing, and test this hypothesis by adapting a standard behavioral measure of memory (the free and cued selective reminding test, FCSRT) to allow for the collection of cued recall latencies. Participants were drawn from five groups: college-aged, middle-aged, healthy elderly, those with a diagnosis of MCI, and a sample of MCI control participants. The measure of capacity is shown to offer increased classificatory sensitivity relative to the standard behavioral measures, and is also shown to be the behavioral measure that correlated most strongly with hippocampal volume.

Short- and Long-Term Implicit Memory in Aging and Alzheimer's Disease

Implicit memory processes were investigated via picture naming in healthy young and older adults and in persons with mild Alzheimer's disease (AD). Repetition priming in picture-naming was intact in all groups over the course of a short retention interval (seconds), and only the AD group revealed a deficit over a longer interval (72 hours). In addition, the AD group showed impaired procedural memory, with no benefit of practice on picture-naming. Impaired long-term priming was related to severity of AD. Both theoretical and methodological implications are discussed.

Does expanded retrieval produce benefits over equal-interval spacing? Explorations of spacing effects in healthy aging and early stage Alzheimer's disease

Three experiments explored different schedules of retrieval practice in young adults, older adults, and individuals with dementia of the Alzheimer type. In each experiment, an initial acquisition phase was presented in which participants studied or attempted to retrieve response words to cues, followed by a later cued-recall test. Experiment 1 produced a benefit of expanded retrieval over equal-interval retrieval during acquisition, but this benefit was lost in final cued recall. In Experiments 2 and 3, participants received corrective feedback during acquisition and modified spacing schedules. There was again no evidence of a difference between expanded and equal-interval conditions in final cued recall. Discussion focuses on the potential benefits and costs of expanded retrieval on a theoretical and applied level.

Learning Facts From Fiction: Effects of Healthy Aging and Early-Stage Dementia of the Alzheimer Type

Healthy younger and older adults and individuals with very mild or mild dementia of the Alzheimer type (DAT) listened to and read fictional stories containing correct and incorrect facts about the world. Of interest was their use of this story information to answer questions on a later test of general world knowledge. Prior exposure to relatively well-known facts boosted all subjects' ability to correctly answer general knowledge questions. Reading incorrect facts in the stories led to misinformation effects in healthy older adults (although these effects were smaller than those observed in younger adults). DAT individuals showed reduced effects of story exposure; effects were greatest in a situation that reminded DAT individuals that the stories might provide the answers to the questions. Benefits of story reading depended on activation of the semantic network, whereas costs of story reading were more dependent on episodic memory processes.

Explicit Contamination Contributes to Aging Effects in Episodic Priming: Behavioral and ERP Evidence

We examined the impact of explicit contamination on age-related changes in episodic priming. We recorded event-related brain potentials (ERPs) from older and younger adults to primed and unprimed nouns tested in a recognition memory task. Results revealed that the magnitude of priming was greater in the younger adults. ERPs revealed a priming effect in the younger adults that was absent in older adults. Findings suggest that explicit contamination may account for the reported aging effect: Item memory was correlated with episodic priming and ERP priming in younger adults, but not older adults; item memory was associated with episodic priming after aging effects were controlled for; and the topographies of the young's priming and item memory effects were indistinguishable. Given the apparent vulnerability to contamination by explicit memory, we suggest caution when researchers use an episodic priming paradigm to assess aging effects in implicit memory.

Phonological Blocking During Picture Naming in Dementia of the Alzheimer Type

Individuals with dementia of the Alzheimer type (DAT; n = 53, ages 55-91), healthy older adults (n = 75, ages 59-91), and younger adults (n = 24, ages 18-24) performed a word-primed picture-naming task. Word primes were neutral (ready), semantically or phonologically related, or unrelated to the correct picture name. AH groups produced equivalent unrelated-word interference and semantic priming effects in response latencies. However, analysis of errors revealed a DAT-related increase of phonological blocking. The results suggest that picture-naming errors in DAT are due, at least in part, to a breakdown in access to phonological representations of object names as a consequence of reduced inhibitory control over other highly active alternatives.

Exploring the Identification-Production Hypothesis of Repetition Priming in Young and Older Adults

The identification-production hypothesis of age-related differences in repetition priming predicts reduced priming in older adults on indirect memory measures that require stimulus production (production priming) together with age constancy on indirect measures that require stimulus identification, verification, or classification processes (identification priming). Although some evidence is consistent with this hypothesis, comparisons of identification and production priming in young and older adults often confound stimulus, subject, and dependent measure factors across tasks. Consequently, repetition priming has yet to be assessed in healthy young and healthy older adults using identification and production tasks that control for these factors. The identification-production hypothesis was tested using verb generation as a measure of production priming (Experiments 1-3) and semantic classification (Experiment 1) or semantic verification (Experiments 2 and 3) as the measure of identification priming. Contrary to the identification-production hypothesis, no age-related diminutions in identification or production forms of priming were found.