Cognitive function is not impaired in people with a long history of migraine: a blinded study.

Little is known about the long-term consequences of migraine for cognitive functioning. This study compared older migraine patients with matched controls on four measures of cognitive ability, in a blinded design. Migraine patients and case-matched controls were recruited from the database records of a pre-existing study of ageing. Data were available from four tests of cognitive ability: verbal/arithmetic problem solving, spatial problem solving, processing speed, and vocabulary. There were no significant differences between the mean scores of migraine and control groups on any of the four cognitive tests. In addition, there were no significant differences between migraine and control groups in the effect of age on any of the four tests. A long history of migraine does not compromise scores on the four cognitive tests used in this study. These tests are predictive of memory and executive functioning in cognitive ageing, but it remains possible that lower-level cognitive processes, particularly as assessed by visual tasks, may be vulnerable to migraine.

Cognitive function in healthy older European adults: the ZENITH study.

OBJECTIVE: Baseline data are reported from a study of the effects of zinc supplementation on cognitive function in older adults as assessed by the CANTAB computerised test battery. DESIGN: This is a multicentre prospective intervention study employing a randomised double-blind design. SETTING: European community-based study. PARTICIPANTS: There are 387 healthy adults aged 55-87 y from centres in France, Italy and Northern Ireland. INTERVENTIONS: Measures of visual memory, working memory and attention were obtained at baseline (prior to supplementation). RESULTS: Younger adults (<70 y) performed significantly better than older adults (>70 y) on all tests, with minimal differences between centres. In addition, men outperformed women on tests of spatial span, pattern recognition memory and reaction times, although these gender differences varied somewhat between centres. CONCLUSIONS: The results are generally consistent with previous age- and gender-related effects on cognitive functioning.

Effects of spatial and nonspatial cognitive activity on postural stability.

Is postural stability controlled automatically, or is it affected by concurrent cognitive activity? Are the effects influenced by the nature of the cognitive activity required, and do they increase in old age? To address these questions, 70 participants aged 20-79 years were asked to stand as still as possible on a force platform (postural control task) while performing (a) no cognitive task, (b) a spatial memory task, and (c) a nonspatial memory task. The memory tasks were also performed while seated as a comparison condition. Both spatial and nonspatial memory recall declined with increasing age but were unaffected by position (standing vs. seated). Postural stability declined with age; moreover, there was support for an earlier finding that age decline was greatest when performing the spatial memory task. Each recording period was split into two phases which, for the spatial and nonspatial memory tasks, corresponded to encoding and maintaining the stimuli. In comparison with no task, participants were more stable when encoding stimuli (particularly in the spatial task), but they were less stable when maintaining stimuli (particularly in the nonspatial task). The results suggest that postural stability can be affected by cognitive activity in complex ways, depending on the age of participants, the type of cognitive task (spatial vs. nonspatial), and the cognitive processing required (encoding vs. maintenance).

Scale invariance in the retrieval of retrospective and prospective memories.

How does memory retrieval depend on time scale? One strong hypothesis is that such retrieval is scale-invariant (i.e., invariant across different time scales). To test this hypothesis, three groups of participants were given 4 min to recall what they did yesterday, last week, or last year (retrospective memories), and 4 min to recall what they intended to do tomorrow, next week, or next year (prospective memories). In line with scale invariance, retrieval performance was indistinguishable across time scales, for both retrospective and prospective memory. An additional finding was that significantly more prospective memories were recalled than retrospective memories, confirming previous observations of the "intention-superiority effect" (Goschke & Kuhl, 1993).

Searching for two things at once: evidence of exclusivity in semantic and autobiographical memory retrieval.

We examined whether retrieval from semantic memory (Experiment 1) and autobiographical memory (Experiment 2) is exclusive, or whether people can search for two things at once. In Experiment 1, participants retrieved items as quickly as possible over 4 ruin from single categories (e.g., foods, countries) and from disjunctive categories (e.g., foods or countries). In Experiment 2, participants retrieved autobiographical episodes associated with single cue words (e.g., flower, ticket) or with disjunctive cue words (e.g., flower or ticket). In both experiments, retrieval of items from the disjunctive category did not exceed predictions based on optimal sequencing of retrieval from the corresponding two single categories. That is, exclusivity was observed to occur in retrieval from among multiple nonoverlapping categories in both semantic and autobiographical memory.

Prospective and retrospective memory in normal ageing and dementia: a questionnaire study.

Frequency of prospective memory and retrospective memory failures was rated on a 16-item questionnaire by 862 volunteers, from five groups: patients with Alzheimer Disease (rated by carers), carers of Alzheimer Disease patients, elderly, young, and a group of married couples. Reported memory failures were highest for Alzheimer Disease patients, and lowest for carers, with elderly and young controls in between. More prospective memory than retrospective memory failures were reported in all groups, although the difference was small for Alzheimer Disease patients who were rated near ceiling for both. Prospective memory failures of Alzheimer Disease patients were reported as more frustrating for carers than retrospective memory failures; prospective memory and retrospective memory failures frustrated Alzheimer Disease patients equally. Data from the couples indicated that there were no biases resulting from rating on behalf of someone else. These results suggest that: (1) normal ageing has no greater effect on self-reported retrospective memory than prospective memory failures, (2) the relatively small number of memory failures reported by carers may result from comparing themselves with the Alzheimer Disease patients in their care, and (3) prospective memory failures have a greater impact on the lives of the carers and are therefore more likely to be reported as early indicants of the disease.

Aging and the Ranschburg effect: no evidence of reduced response suppression in old age.

Two experiments tested 1 aspect of L. Hasher and R. T. Zacks's (1988) reduced inhibition hypothesis, namely, that old age impairs the ability to suppress information in working memory that is no longer relevant. In Experiment 1, young and older adults were asked to recall lists of letters in the correct order. Half of the lists contained repeated items while half were control lists. Recall of nonadjacent repeated items was worse than that of control items. This Ramschburg effect was larger (i.e., greater response suppression) in older than in young adults. In Experiment 2, young and older adults were required either to recall the list or to report if there was a repeated item. Repetition detection was high and similar in the 2 age groups. When age differences in overall performance were taken into account, there was evidence of increased repetition inhibition with age in both experiments. Thus, contrary to the general reduced inhibition hypothesis, the specific process of response suppression during serial recall is not reduced by aging.

Developmental changes in time estimation: comparing childhood and old age.

Participants from ages 5 to 99 years completed 2 time estimation tasks: a temporal generalization task and a temporal bisection task. Developmental differences in overall levels of performance were found at both ends of the life span and were more marked on the generalization task than the bisection task. Older adults and children performed at lower levels than young adults, but there were also qualitative differences in the patterns of errors made by the older adults and the children. To capture these findings, the authors propose a new developmental model of temporal generalization and bisection. The model assumes developmental changes across the life span in the noisiness of initial perceptual encoding and across childhood in the extent to which long-term memory of time intervals is distorted.

Adult age differences in short-term memory for serial order: data and a model.

Age-related deficits in short-term memory have been widely reported, but reduced overall scores could reflect increased order errors, increased omissions, or increased intrusions. Different explanations for reduced short-term memory with aging lead to different predictions. In this study, young (n = 68; M age = 20 years) and older (n = 99; M age = 65 years) adults were presented with lists of letters and were asked to recall each list immediately in the correct order. Age differences in error patterns were similar for auditory and visual presentation. For example, older adults made more errors of every type, and a greater proportion of the older adults' errors were omissions. An additional condition, in which older adults were encouraged to guess, ruled out an age increase in response threshold as a full explanation for the results. The data were modeled by an oscillator-based computational model of memory for serial order. A good fit to the aging data was achieved by simultaneously altering two parameters that were interpreted as corresponding to frontal decline and response slowing.

Retrieving names in old age: short- and (very) long-term effects of repetition.

Two experiments are reported that examine the effects of repetition on name retrieval in younger adults (in their 50s and 60s) and older adults (in their 70s and 80s). In Experiment 1, the subjects were asked to name a set of famous faces four times over the course of a 1-h session. Younger subjects produced significantly more correct responses than did older subjects. There was significant improvement with repeated attempts at naming, with younger and older subjects benefiting equally in terms of increasing numbers of correct responses across the session. In contrast, there was a highly significant age deficit in picture recognition over a similar retention interval. A qualitative analysis of naming responses (full name vs. part of the name) provided support for the view that aging and nonrecent use have equivalent effects on retrieval. In Experiment 2, younger subjects (but not older subjects) were significantly more likely to correctly name famous faces that they had seen 22 months previously than to correctly name new famous faces. In contrast, older subjects (but not younger subjects) were significantly more likely to produce erroneous names to famous faces that they had seen 22 months previously than to new famous faces. It is concluded that repetition priming may be relatively unaffected by aging over short retention intervals (Experiment 1) but not over a very long retention interval (Experiment 2).

The influence of perceptual load on age differences in selective attention.

The effect of perceptual load on age differences in visual selective attention was examined in 2 studies. In Experiment 1, younger and older adults made speeded choice responses indicating which of 2 target letters was present in a relevant set of letters in the center of the display while they attempted to ignore an irrelevant distractor in the periphery. The perceptual load of relevant processing was manipulated by varying the central set size. When the relevant set size was small, the adverse effect of an incompatible distractor was much greater for the older participants than for the younger ones. However, with larger relevant set sizes, this was no longer the case, with the distractor effect decreasing for older participants at lower levels of perceptual load than for younger ones. In Experiment 2, older adults were tested with the empty locations in the central set either unmarked (as in Experiment 1) or marked by small circles to form a group of 6 items irrespective of set size; the 2 conditions did not differ markedly, ruling out an explanation based entirely on perceptual grouping.

Age differences in postural stability are increased by additional cognitive demands.

We report an investigation of postural stability in two groups of volunteers (mean ages of 57 and 77). Participants were required to stand on a force platform while performing five cognitive tasks: (1) random digit generation, (2) Brooks' spatial memory, (3) backward digit recall, (4) silently counting from 1-100, and (5) counting backward in threes (aloud). There was also a control condition in which there was no cognitive task. Postural stability was adversely affected by age in all conditions. Moreover, the difference between the two age groups was significantly greater when performing tasks 2 and 3, in comparison with the age difference in the control condition. Regression analyses revealed that the effect of age on postural stability while performing these particular tasks remained significant even after the following measures were included in the regression: postural stability in the control condition, cognitive performance, intelligence, and speed. We suggest that age differences in postural stability are increased by cognitive tasks requiring use of the visuo-spatial sketchpad component of working memory.

Age-related impairment in an event-based prospective-memory task.

Slides of famous people were presented to participants with the instructions to name each face and circle the trial number if the person was wearing glasses (prospective-memory target event). Participants in their 50s and 60s (n = 56) were more successful than participants in their 70s and 80s (n = 59) at both the naming an prospective-memory tasks. An age-related increase in the probability of forgetting replicated an earlier prospective-memory study (E. A. Maylor, 1993); in the present case, there was also an age-related decrease in the probability of recovery. These effects of age remained significant after other measures of current ability were taken into account, including intelligence, speed, and naming performance. For participants who were in both the earlier study (E. A. Maylor, 1993) and this study (n = 65), the correlation between prospective-memory performance on the 2 occasions was significant but only for younger participants. Performance in the prospective-memory task was entirely unrelated to performance in the naming task.

Investigating Individual Differences in a Serial Choice Reaction Time Task: Use of Auditory Feedback and Analysis of Responses Surrounding Errors.

Subjects (N = 78) performed a visual four-choice reaction time (RT) task, either with or without immediate trial-by-trial feedback, in which RT (but not accuracy) was indicated by the pitch of an auditory tone. For each feedback condition, half of the subjects (the high AH4 group) scored more than 50% on the AH4 test of fluid intelligence (Heim, 1968), whereas the remaining half (the low AH4 group) scored less than 50%. It was predicted that if low AH4 subjects were slow because they were poor at monitoring RT, they would benefit more from feedback than high AH4 subjects would. This was not supported by the data: There was some beneficial effect of feedback on RT, but only for the high AH4 group. A second possibility was that individual differences would be apparent in processes such as detecting errors and controlling RT from trial to trial. From analyses of error rates, RT distributions, and particularly sequences of responses before and after errors, there was no evidence of qualitative differences in performance between the high and low AH4 groups. It is concluded that individual differences in this task are largely determined by information-processing rate rather than by factors such as the ability to detect errors or to monitor and control RT.

Flashbulb memories in older adults.

In this study of age differences in flashbulb memory, groups of young and older adults gave detailed accounts of how they heard the news of the resignation of the British Prime Minister Margaret Thatcher. They were tested within 14 days after the event and again 11 months later. They also gave ratings for the encoding variables (surprise, emotion, importance, knowledge, and interest) and for frequency of rehearsal. Memories that met a strict criterion of consistency between the original and delayed responses were classified as flashbulb memories. Although 90% of young Ss had flashbulb memories, only 42% of the elderly met the criterion. The age groups also differed in the type of details remembered and in the relationship between the encoding and rehearsal variables and the occurrence of flashbulb memory. The age-related deficit in flashbulb memory is related to source amnesia and to a deficit in memory for context.

Applying Brinley plots to individuals: effects of aging on performance distributions in two speeded tasks.

This article describes the application of Brinley plots to performance distributions from 2 speeded tasks, namely, letter coding and visual search. Ss were aged either 60 years (n = 111) or 75 years (n = 111). Response times within each age group were ranked and then plotted against each other so that the best 60-year-old was paired with the best 75-year-old, and so on. For both tasks, linear fits to the functions were almost perfect, with slopes greater than 1 and with negative intercepts. Additive and multiplicative models of aging were rejected in favor of a general linear model, with different parameters for the letter coding and visual search tasks.

Ageing and the retrieval of specialized and general knowledge: performance of Masterminds.

Contestants in the television quiz show Mastermind attempt to answer correctly as many questions as possible in two minutes on: (1) A specialized subject of their own choosing and (2) general knowledge. In this study, past contestants were asked to provide details of their performance in the competition. It was predicted that younger contestants would outperform older contestants under the speeded conditions of Mastermind because of their superior fluid intelligence. The main results were as follows: (1) Higher scores and lower tip-of-the-tongue (TOT) rates were achieved in the specialized subject round than in the general knowledge round. (2) TOT rate was positively related across the two rounds. (3) There was no effect of age on performance in the specialized subject round. In the general knowledge round, age was positively correlated with both score and accuracy. Thus, contrary to predictions, the older contestants actually outperformed the younger contestants (at least in the general knowledge round), presumably because of their superior crystallized intelligence. The results are discussed in terms of 'limited impact' theories of ageing, such that age-related decline in fluid intelligence does not necessarily occur for (a) everybody or (b) everything.

Aging and forgetting in prospective and retrospective memory tasks.

Ss aged 52-83 years were asked to name 30 famous people 4 times over the course of an hour and to respond to 2 targets (a beard and a pipe) by marking the trial number on the response sheet. Initial performance in the prospective memory task was related only to a measure of incidental learning. Subsequent forgetting (i.e., success followed by failure) occurred more often for older Ss than for younger Ss, but there was no difference between the age groups in recovery (i.e., failure followed by success). Forgetting was predicted by age, even after a composite measure of general ability was included in the regression. Recovery was related to general ability alone. These results both replicate and extend those from a reanalysis of a previous study (Maylor, 1990a). They provide a striking contrast with the effect of age on retrospective memory, namely, age-related impairment on initial performance but no effect of age on subsequent forgetting.

Alcohol, reaction time and memory: a meta-analysis.

Moderate doses of alcohol impair performance on a variety of information processing tasks. Two separate meta-analyses were conducted on the results of (1) reaction time studies, and (2) recognition memory studies, representing 25 and 16 different task conditions, respectively. In both cases, performance with alcohol (either 0.8 or 1.0 ml/kg body weight) was plotted as a function of performance with no alcohol. For reaction time, a linear fit accounted for 99.7 per cent of the variance. The same function applied not only to the mean but to the distribution of reaction times from the 5th to the 95th percentiles. For recognition memory, a linear fit accounted for 96.2 per cent of the variance in accuracy (expressed as the logarithm of proportion correct). Thus alcohol appears to have a general linear effect on information processing, rather than specific effects on a subset of stages. It is concluded that the results are consistent with a reduced processing resources hypothesis for the impairment with alcohol.

Linear and nonlinear effects of aging on categorizing and naming faces.

Subjects aged 54-84 performed 5 separate tasks involving various aspects of face processing: structural decisions (1), familiarity decisions (2), semantic decisions (3), first-name decisions (4), and name retrieval (5). For the categorization tasks (1-4), the mean reaction times for the older subjects (over 65) were plotted against the corresponding means for the younger subjects (under 65). This produced a linear function (slope greater than 1, intercept less than 0), providing only partial support for a simple, multiplicative model of cognitive slowing with age. Reaction time distributions were also plotted for each of the 5 tasks (older vs. younger subjects). The resulting functions were almost perfectly linear, with the exception of name retrieval, which was exponential with respect to age. This was attributed to the increased probability of a tip-of-the-tongue state with age caused by insufficient activation at the level of the name information (the final state of face identification).