Biomedical subjects

Fergus I M Craik

Publications and source records attributed to Fergus I M Craik.

33 records · Page 2Linked to original sources

PubMed2003

The effects of aging and divided attention on memory for item and associative information.

The present study examined how aging and divided attention influence memory for item and associative information. Older adults and younger adults working under full-attention conditions and younger adults working under divided-attention conditions studied unrelated word pairs. Memory for item information was measured by later recognition of the 2nd word in the pair, and associative information was measured by recognition of the entire pair. Both older adults in the full-attention condition and younger adults in the divided-attention condition performed more poorly than younger adults in the full-attention condition, with the deficit in associative information being greater than the deficit in item information. In addition, a differentially greater associative decrement was found for the older adults, as shown by their heightened tendency to make false-alarm responses to re-paired (conjunction) distractors. The results are discussed in terms of an age-related reduction in processing resources compounded by an age-related increase in older adults' reliance on familiarity in associative recognition memory.

Adult↗

PubMed2003

The role of spatial working memory in inhibition of return: evidence from divided attention tasks.

Inhibition of return (IOR) refers to a bias against returning attention to a location that has been recently attended. In the present experiments, we examined the role of working memory in IOR by introducing secondary tasks (in the temporal interval between the cue and the target) that involved a working memory component. When the secondary task was nonspatial in nature (monitoring odd digits or adding digits), IOR was present, although overall reaction times were greater in the presence of the secondary task. When the task involved a spatial working memory load (remembering the directionality of arrows or the orientation of objects), IOR was eliminated. However, when the participants had incentive to process the directionality of an arrow but did not have to use any memory system, IOR persisted at peripheral locations. Overall, the results suggest that IOR is partially mediated by a spatial working memory system.

Attention↗

PubMed2002

Lapses of intention and performance variability reveal age-related increases in fluctuations of executive control.

We examine the hypothesis that the efficiency of executive control processes is less stable over time in older than younger adults. An age-related decrease in the efficiency of executive control should result in an increase in performance variability in task conditions requiring the recruitment of executive control processes and not in task conditions requiring minimal involvement of executive control. Performance variability was similar for younger and older adults in task conditions requiring minimal executive control and greater for older than younger adults in task conditions requiring executive control. These and other data are consistent with the proposal that aging is associated with a decrease in the stability of executive control over time.

Adult↗

PubMed2002

Effects of divided attention on episodic memory in chronic traumatic brain injury: a function of severity and strategy.

Eleven patients with mild traumatic brain injury (MTBI) and 13 patients with moderate-to-severe TBI (STBI) were compared to 10 matched controls on episodic memory for pictorial scene-object associations (e.g. kitchen-bread) and a range of standardized neuropsychological tests of memory and frontal-lobe functions. We tested the hypothesis that deficits in episodic memory result from impaired attentional resources and/or strategic control by manipulating attentional load at encoding (focused versus divided attention) and environmental support at retrieval (free recall and recalled cued by scene versus recognition of object and scene). Patients with TBI were disproportionately affected by the divided attention manipulation, but this effect was modulated by injury severity and encoding strategy. Overall, MTBI patients were impaired only when items were encoded under divided attention, indicating memory deficits that were secondary to deficits in the executive control. STBI patients could be differentiated into two distinct functional subgroups based on whether they favored a strategy of attending to the encoding or digit-monitoring task. The subgroup favoring the digit-monitoring task demonstrated deficits in the focused attention condition, and disproportionate memory deficits in the divided attention condition. In contrast, the subgroup favoring the encoding task demonstrated intact performance across all memory measures, regardless of attentional load, and despite remarkable similarity to the other STBI subgroup on demographic, neuropsychological, and acute injury severity measures. We discuss these outcome differences in terms of the relationship between strategy and executive control and highlight the need for more sensitive anatomical and behavioral measurement at both acute and chronic stages of injury.

Adult↗

PubMed2002

Effects of time of day on age differences in working memory.

This study investigated the hypothesis that the influence of time of day on the efficiency of working memory is greater for older than younger adults. Groups of younger and older adults performed a working memory task on 4 consecutive days, twice in the morning and twice in the evening. Objective (body temperature) and subjective (alertness ratings) measures of arousal were taken during each session. Temperature increased across the day equally for younger and older adults, whereas alertness ratings were higher in the morning for older adults and in the evening for younger adults. The efficiency of the access and deletion functions paralleled the subjective alertness rating for younger and older adults, and age-related differences in these functions were greater when individuals were tested at nonoptimal times of day. The efficiency of the response inhibition function was similar for younger and older adults and paralleled changes in body temperature.

Adult↗

PubMed2002

The effects of aging on selectivity and control in short-term recall.

The ability to control encoding and retrieval processing strategically is critical for the efficient use of memory. We examined the ability of younger and older adults to selectively remember words on the basis of their arbitrary point values by using a technique developed by Watkins and Bloom (1999). In the first three experiments, younger subjects recalled more words than did older subjects, but an independent index of recall selectivity showed that older subjects were apparently more successful in selecting higher valued words. However, a fourth experiment showed that this superior selectivity on the part of older adults was attributable to their greater proportional reliance on primary memory recall. Overall, the data suggest that although older adults recall fewer words than do younger adults, they exert as much control over some aspects of encoding.

Adult↗

PubMed2000

Comparing the effects of aging and background noise on short-term memory performance.

Paired associate recall was tested as a function of serial position for younger and older adults for five word pairs presented aurally in quiet and in noise. In Experiment 1, the addition of noise adversely affected recall in young adults, but only in the early serial positions. Experiments 2 and 3 suggested that the recall of older adults listening to the words in quiet was nearly equivalent to that of younger adults listening in noise. In Experiment 4, we determined the signal-to-noise ratio (S/N) such that, on average, younger and older adults were able to correctly hear the same percentage of words when words were presented one at a time in noise. In Experiment 5, younger adults were tested under this S/N. Compared with older adults from Experiment 3, younger adults in this experiment recalled more words at all serial positions. The results are interpreted as showing that encoding in secondary memory is impaired by aging and noise either as a function of degraded sensory representations, or as a function of reduced processing resources.

Adult↗

PubMed1992

Age-related differences in memory as a function of imagery processing.

The effects of aging on imagery production and use--following the learning of concrete and abstract words--and their relations to subsequent memory performance were explored in 2 experiments. Both experiments demonstrated better free recall of concrete than of abstract words (the concreteness effect). Experiment 1 showed this superiority to be greater for young subjects only under explicit imagery instructions. Experiment 2 revealed that the advantage of concrete over abstract words reflects the use of differential imagery production. The results are discussed in terms of age differences in imagery utilization and the effects of visual processing on recall.

Adult↗

PubMed1992

Age-related differences in three tests of visual imagery.

Adult age differences were explored on 3 short tests of the ability to generate and manipulate mental images. Age-related decrements were found in all 3 tests and were especially marked on the Clock Test. The tests are all reliable, as shown by test-retest reliability coefficients. Correlations also revealed that the Brooks Letter Test and the East-West Test appear to tap one common underlying ability, whereas the Clock Test measured a somewhat different ability. The East-West and Clock tests, in particular, may provide rapid and easily administered assessments of age-related changes in aspects of mental imagery.

Adult↗

PubMed1990

Relations between source amnesia and frontal lobe functioning in older adults.

A study is reported in which the relations among normal aging, source amnesia, and frontal lobe functioning were explored. Twenty-four older adults (aged 60-84 years) were tested on their ability to remember where they had acquired new factual information; they were also given the Wisconsin Card Sorting Test (WCST), a test of verbal fluency, and other psychometric tests. The degree of source amnesia in this normal sample correlated with age, verbal fluency, and some measures from the WCST. Source amnesia was not related to Performance IQ, however, or to a measure of fact recall. The implications for the relations among aging, memory, and frontal lobe functions are discussed.

Age Factors↗

PubMed1988

Effects of aging and task difficulty on divided attention performance.

We report two experiments that compare the performance of young and older adults on perceptual-motor tasks involving division of attention. Previous studies have shown older people to be especially penalized by divided attention situations, but the generality of this finding was recently challenged by Somberg and Salthouse (1982). The present study was conducted to investigate the possibility that age differences in dual-task performance are amplified by an increase in the difficulty of the constituent tasks, where difficulty was manipulated by varying the central, cognitive nature of the tasks (Experiment 1) or the degree of choice involved (Experiment 2). With the present tasks, strong evidence was found for an age-related decrement in divided attention performance. Contrary to our original expectations, however, it does not seem that division of attention presents some especial difficulty to older people. Rather, division of attention is one of several equivalent ways to increase overall task complexity. In turn, age differences are exaggerated as tasks are made more complex.

Adult↗

PubMed1987

Patterns of memory loss in three elderly samples.

Three groups of people ranging in age from 64 to 88 years performed tasks of word generation, paired-associate recall, and free and cued recall. The groups differed in socioeconomic status, verbal intelligence, and apparent levels of daily activity. A fourth group, consisting of young undergraduates, was also tested. Results showed that whereas there were age-related differences in some tests, these age differences were strongly modulated by characteristics of the participants and characteristics of the tasks. The findings are discussed in a contextualist framework.

Activities of Daily Living↗

PubMedDate not supplied

Executive function across the life span.

The development and determinants of executive function (EF) were studied in children (mean age=8.8 years), young adults ( M= 22.3 years), and elderly adults (M = 71.1 years). EF was indexed by perseverative responding on two bidimensional sorting tasks (Visually Cued Color-Shape task and Auditorily Cued Number-Numeral task), and age-related changes in EF were considered in relation to estimates of conscious vs. unconscious memory that were obtained using the process dissociation procedure (PDP). Results revealed the rise and fall of EF across the life span, with significant quadratic trends found for performance on both sorting tasks and for the conscious recollection component (C) of the PDP task. Regression analyses indicated that PDP estimates of conscious memory accounted for variation in performance on the visual sorting task, but not on the auditory sorting task. The findings are discussed in terms of their implications for hierarchical models of EF and its development.

Adult↗

PubMedDate not supplied

The effects of attention switching on encoding and retrieval of words in younger and older adults.

Two experiments examined the interaction between aging, attention switching, encoding process, and recognition memory using different versions of a cued attention switching paradigm. In Experiment 1, 30 younger and 35 older adults encoded words based on font color, meaning, or by explicit learning with a color response during performance of a choice-reaction time (RT) task. Attention switches were cued by means of stimulus location, and occurred on average every seven trials. In Experiment 2, attention switching was precued from a central fixation point and the number of critical switch trials was increased, occurring on average every four trials. Memory was assessed in both experiments by means of a forced-choice recognition task. Results indicated that, relative to color encoding, older adults benefited more than younger adults from semantic encoding, but less from explicit learning instructions. Attention switching disrupted encoding task performance of older adults more than that of younger adults, but recognition memory was generally unaffected. Results are discussed in light of theoretical models of aging memory that posit a role for executive control processing.

Adolescent↗

PubMedDate not supplied

Levels of processing: past, present. and future?

In this article I first briefly survey some enduring legacies of the Craik and Lockhart (1972) article on levels of processing (LOP) and address some common criticisms. In the next section I discuss whether memory can be regarded as "pure processing", the role of short-term memory in an LOP framework, measurement of "depth" in LOP, encoding-retrieval interactions, the concept of consolidation, and the reality of "levels" of processing. In the final section I offer some speculations on future directions, discussing the notion of levels of representation and a possible continuing role for LOP in memory research.

Forecasting↗