Biomedical subjects

T J Perfect

Publications and source records attributed to T J Perfect.

14 recordsLinked to original sources

PubMed2001

Deep dysphasic performance in non-fluent progressive aphasia: a case study.

We present a patient (PW) with non-fluent progressive aphasia, characterized by severe word finding difficulties and frequent phonemic paraphasias in spontaneous speech. It has been suggested that such patients have insufficient access to phonological information for output and cannot construct the appropriate sequence of selected phonemes for articulation. Consistent with such a proposal, we found that PW was impaired on a variety of verbal tasks that demand access to phonological representations (reading, repetition, confrontational naming and rhyme judgement); she also demonstrated poor performance on syntactic and grammatical processing tasks. However, examination of PW's repetition performance also revealed that she made semantic paraphasias and that her performance was influenced by imageability and lexical status. Her auditory-verbal short-term memory was also severely compromised. These features are consistent with 'deep dysphasia', a disorder reported in patients suffering from stroke or cerebrovascular accident, and rarely reported in the context of non-fluent progressive aphasia. PW's pattern of performance is evaluated in terms of current models of both non-fluent progressive aphasia and deep dysphasia.

Anomia↗

PubMed2000

Evidence for intact memory monitoring in Alzheimer's disease: metamemory sensitivity at encoding.

Previous research claiming that there is a metamemory deficit in Alzheimer's Disease (AD) has been based on paradigms in which metamemory judgements are compared with performance. These methods confound predictive accuracy with very poor memory performance. In the experiments presented here this confound is removed by focusing on the sensitivity of metamemory judgements to item differences at encoding, rather than on predictive accuracy. In Experiment 1 participants studied words of high or low recallability, and either made judgements of learning (JOLs) or declared recall readiness. It was found that the AD group discriminate between items in their metamemory judgements to the same extent as age matched controls. Both groups rated the highly recallable words as being more likely to be recalled, and allocated more study time to low recallability items. In Experiment 2 participants were asked to rank the likelihood of recall of items that varied in objective recallability. Once again, AD patients were as sensitive to objective differences in stimuli as controls. Therefore, using measures based on sensitivity to item differences, we find no evidence of a metamemory deficit at encoding in AD. The findings are discussed in terms of metamemory functioning in AD, and its relationship with memory performance.

Aged↗

PubMed2000

The effects of repetition on allocation of study time and judgements of learning in Alzheimer's disease.

Greene et al. [12] suggest that Alzheimer's disease (AD) patients approach repeated trials in a learning test as if they are single unrelated trials. Previous research [7] indicates that AD patients do not have explicit memory for item repetition when asked at test how many times a word was presented, but they do show benefits of repeated presentation in implicit tasks. In this experiment we examine metacognitive judgements made during study for repeated items. It was hypothesised that a lack of awareness of repetition may exacerbate the episodic memory impairment found in AD. To explore this, two measures of metamemory were taken for items presented once, twice or three times in a list: judgements of learning (JOLs), which are a declaration of how well an item has been learned, and recall readiness, which is the study time allocated by participants to ensure proficient learning of an item. With repetition, age matched controls made recall readiness judgements more quickly and reported higher JOLs. The AD patients showed faster recall readiness, but did not alter their JOLs. This suggests a dissociation in the AD group between judgements of learning and the allocation of study time. We discuss the implications for theories of the learning deficit in AD, and the use of metamemory measurements in clinical populations.

Aged↗

PubMed2000

Practice and feedback effects on the confidence-accuracy relation in eyewitness memory.

It has been claimed that the lack of a reliable confidence-accuracy relation in eyewitness memory stems from eyewitnesses' lack of knowledge concerning their relative expertise. Two studies tested this idea by contrasting the effects of practice alone with practice with feedback in three successive eyewitness tests. Experiment 1 tested recall for events, and Experiment 2 used recognition of faces as test materials. Both studies showed that practice alone did not increase the confidence-accuracy relation, but practice with feedback on relative performance produced robust increases in the confidence-accuracy relation. This suggests that lack of calibration is one factor that causes the reported lack of association between confidence and accuracy for eyewitness memory.

Adolescent↗

PubMed1997

Changes in memory awareness during learning: the acquisition of knowledge by psychology undergraduates.

First-year psychology students took multiple-choice examinations following each of 4 lecture courses and 3 laboratory research methods courses. One lecture course was later retested. Students indicated state of memory awareness accompanying each answer: recollective experience (remember), "just know" (know), feeling of familiarity (familiarity), or guess. On the lecture courses, higher performing students differed from other students because they had more remember responses. On research methods, higher performing students differed because they knew more, and in the delayed retest, higher performing students differed because they now knew rather than remembered more. These findings demonstrate a shift from remembering to knowing, dependent upon level attained, type of course, and retention interval, and suggest an underlying shift in knowledge representation from episodic to semantic memory. The authors discuss theoretical and educational implications of the findings.

Achievement↗

PubMed1997

What underlies the deficit in reported recollective experience in old age?

In recognition memory, older adults report fewer occasions on which recognition is accompanied by recollection of the original encoding context. This study asks why this occurs. Two main hypotheses were tested: (1) Older adults fail to encode the items sufficiently when first they experience them. (2) Older adults have a retrieval deficit that prevents efficient reintegration of target and context. In addition, the hypothesis that frontal lobe integrity is essential for recollective experience was examined. Twenty older (mean age 70.7 years) and 20 younger (mean age 22.9 years) adults were asked to study a list of items and to verbalize the strategies they were using to remember. A further 20 older adults (mean age 70.0 years) were tested without the think-aloud protocol. Subsequently, subjects completed a battery of psychometric tests before completing a recognition test. As expected, older adults showed less recollective experience. They differed from the young in how they encoded the material, and once this difference was accounted for, no age differences in recollective experience remained. There was little evidence to support the hypothesis that frontal lobe integrity plays a role in the reduction of recollective experience with age.

Adult↗

PubMed1996

Stem-completion priming in Alzheimer's disease: the importance of target word articulation.

Stem-completion priming performance in patients with Alzheimer's type dementia (DAT) was explored in three experiments in which both the standard repetition priming effect and a novel indirect form of priming, cohort priming, were measured. In the first experiment, in which study stimuli were words, both priming effects were found to be markedly attenuated in the DAT group. In the second experiment, the study stimuli were specially constructed nonwords, and it was found that cohort priming was present at normal levels in the DAT group. In a third experiment we tested the specific hypothesis that the requirement to overtly articulate target stimuli during the study phase was critical for the appearance of normal cohort priming in the DAT group in Experiment 2, and also for the normal levels of repetition priming which have been reported in some published studies. Two encoding conditions were compared, one in which subjects simply had to read aloud the target words and a second in which subjects were required to make evaluative (pleasantness) ratings for each of the target words (identical to that used in Experiment 1). Stem-completion priming performance following the latter condition was significantly attenuated in the DAT group relative to a healthy control group, but following the "read aloud" encoding condition, normal levels of repetition and cohort priming were observed. It is suggested that the most fruitful approach to understanding the performance of DAT subjects on lexical repetition priming tasks will involve a detailed analysis of language functions and how they interact with other, possibly mnemonic, processes in the generation of primed responses.

Aged↗

PubMed1996

Does context discriminate recollection from familiarity in recognition memory?

Five experiments were conducted to examine subjects' ability to make contextual judgements about recognized items for which they report recollective experience or only familiarity within the context of the experiment. In the first four experiments, subjects were able to make judgements of the spatiotemporal context of items that were accompanied by recollective experience significantly better than for items they merely found familiar. In only one of the four studies did subjects display above-chance performance on spatiotemporal judgements for merely familiar items. A fifth experiment examined the frequency with which subjects report the presence of different kinds of contextual knowledge during a standard recognition experiment. All aspects of contextual knowledge were reported with higher frequencies for recollected items than for items only found familiar, although no single contextual feature was strongly associated with recollective experience. Thus, the five studies together provide converging evidence for the validity of the "recollect-know" distinction in recognition memory and supplement studies that have already demonstrated that the two kinds of response are dissociable. The implications of these data for group comparisons of memory-impaired patients, and the role of context in recognition memory are discussed.

Adult↗

PubMed1995

Age differences in reported recollective experience are due to encoding effects, not response bias.

Three experiments examined whether reduced recollective experience reported in old age is due to a criterion shift towards more cautious responses by older subjects. In Experiment 1 Young and Old subjects took a recognition test without specific instructions on how they should encode the presented words. For recognised items subjects indicated whether they recollected the item's previous occurrence or whether they just knew it had been on the list. They then rated their confidence that the word came from the study list. Although overall recognition levels were equivalent, older adults recollected less and reported more know responses than the younger subjects. However, there was no overall difference in confidence, contrary to a criterion shift explanation. In Experiment 2A specific encoding instructions removed the age-related change in recollective experience entirely. Experiment 2B reproduced the test conditions of Experiment 2A, but without specific encoding instructions, and replicated the pattern of know responding found in Experiment 1. Thus the three experiments together suggest that the amount of recollection experienced by the elderly is not explicable in terms of cautiousness, but is driven by the encoding carried out by the elderly at presentation.

Age Factors↗

PubMed1994

What can Brinley plots tell us about cognitive aging?

The use of Brinley plots (the plotting of the mean response latencies of old adults against the mean latencies for younger adults) has recently become increasingly popular, not least because simple, coherent functions can be determined that account for a large proportion of the variance in performance across tasks. This has led some authors to question the need for a modular approach to cognitive aging and has led to attempts to replace such an approach with accounts based on global central nervous system factors. However, use of simulated data to test the efficacy of Brinley plots shows that their apparent success in predicting high levels of variance may be misleading in two ways: (a) Brinley type plots fail to detect occasions when data are generated specifically not to conform to a single function; and (b) the parameter values obtained differ significantly from the underlying functions used to generate the test data. It is suggested that high correlations between young and old reaction times across tasks that have been widely reported in the literature are not in themselves sufficient to support the strong claims made regarding global models of cognitive aging.

Adolescent↗

PubMed1993

Memory and metamemory performance in older adults: one deficit or two?

In two separate experiments, three groups of older adults (50-80 years old) were shown lists of forename-surname pairs. At test subjects were cued with the surname and asked whether they knew the forename (prospective evaluation). Subjects attempted recall for those items they claimed to know and rated their confidence in their answer (retrospective evaluation). In Experiment 1 subjects saw the name list on 5 successive occasions and attempted recall after each. The older subjects recalled fewer items, but there were no age differences on retrospective memory evaluation. There was a marginally significant age effect on the prospective memory evaluation, which on closer inspection appeared to be a scaling effect related to recall performance. Experiment 2 verified this conclusion in a sample of older adults taking part in a training study extended over many weeks. The main implication of this work is that studies that compare metamemory accuracy in groups that differ in baseline memory performance should be careful before drawing conclusions about metamemory independently of memory performance.

Age Factors↗

PubMed1993

Speed and accuracy of memory decisions in older adults.

An experiment examined the speed and accuracy with which older individuals made decisions about the contents of their memory. 63 volunteers aged between 50 and 80 years made speeded decisions about whether they knew the meaning of rare words presented to them on a computer screen followed by a forced-choice recognition test to assess the veracity of the memory decisions. Subjects were required to select 3 targets from a list of 10 that together constituted the definition of the original word. Analysis showed (i) the older adults were slower to decide whether or not they knew the words, (ii) positive decisions were quicker when more was known about the target, (iii) the age difference in decision speed was unrelated to the amount known about each item.

Aged↗

PubMed1992

The tip-of-the-tongue phenomenon: do experimenter-presented interlopers have any effect?

When a person is in a tip-of-the-tongue (TOT) state, they will sometimes recall a word that is similar in sound to the word they are attempting to retrieve. Woodworth (1929) argued that these interloper words both cause and sustain TOT states, whereas Brown and McNeill (1966) suggested that they are part of the process that leads to TOT resolution. Jones and Langford (1987) and Jones (1989) explicitly presented interloper words along with definitions of words that subjects were asked to recall. They reported that interlopers that were phonologically related to the target word increased the incidence of TOTs and concluded that this supported Woodworth's position. In three experiments, we adopted the interloper paradigm, but also included a control group who heard the definitions without interloper words. In Experiment 1, the definitions that Jones used with phonological interlopers created more TOTs even when no interlopers were presented. In Experiments 2a and 2b, we matched definitions for the number of TOTs they produced in the absence of interlopers. Under these circumstances we found no effect of interloper words at all. We conclude that there is no evidence from this paradigm to support the idea that interloper words are involved in either the causation or resolution of TOTs.

Adult↗

PubMed1992

Preserved implicit memory for lexical information in Alzheimer's disease.

Recent studies have suggested that there is a specific impairment of implicit memory for lexical priming in Alzheimer's Disease. However, there are problems in accepting data from the word-stem completion paradigm as evidence of pure implicit-memory performance. To assess whether Alzheimer's Disease patients are relatively impaired on implicit memory for lexical information an anagram-solution task was adopted. A group of 16 early stage Alzheimer's Disease patients and a group of 16 normal elderly subjects were presented a list of 40 target words. Subsequent free recall was significantly poorer in the former group, but while both groups were significantly better at solving anagrams for words they had previously seen, there was no difference between the two groups in the amount of priming. The data are consistent with the view that previous reports of an implicit deficit in Alzheimer's Disease may not generalise to implicit tasks independent of explicit-memory performance.

Aged↗