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Allocation of attention to programming of movement sequences in Parkinson's disease.

The allocation of attention to the programming and execution of movement sequences was examined in Parkinson's disease (PD). The time taken to initiate and execute sequences of one, three, and five button taps was examined, while also varying the hand used (left or right) and the attentional resources that could be allocated to sequencing (using single- versus dual-task conditions). These results showed that performance anomalies in PD were most apparent with the preferred right hand under single-rather than dual-task conditions. Subjects suffering from PD may tend to divert attention from the right hand under single-task conditions, and perhaps with short sequences, as well as being less likely to prepare sequences of more than three movements in advance with that hand. These effects were unlikely to reflect asymmetric pathology. If the right hand of such subjects has in some respects now come to behave more like a "clumsy" left hand, this may reflect a deliberate strategic choice in an attempt to cope with a movement impairment.

Aged↗

Picture and motor sequencing in multiple sclerosis.

Previous studies consistently report that patients with multiple sclerosis (MS) perform poorly on the Picture Arrangement subtest of the Wechsler Intelligence test. Although this finding implies that MS causes difficulties in cognitive sequencing, the Picture Arrangement test taps many cognitive abilities in addition to sequencing, and the reported deficits by MS patients could reflect difficulties in other skills such as information processing speed or visual acuity and scanning. To circumvent some of these interpretive problems, we used an untimed test of sequencing that required arranging relatively large drawings of familiar scenarios. The MS patients were impaired on this picture sequencing test, but they performed normally on the Luria three-step test of motor sequencing. Correlational analyses showed that picture and motor sequencing were highly correlated, and that performance on both sequencing tests was related to performance on a global mental status exam, the Wisconsin Card Sorting Test and Benton's Facial Recognition Test, but not to upper limb speed and dexterity. These findings demonstrate a relatively specific deficit in cognitive sequencing by MS patients, that can be partially dissociated from impairment in performing simple motor acts.

Adult↗

Working memory in individuals with HIV infection.

The central executive component (CE) of Baddeley's working memory model (Baddeley, 1992) was evaluated in 26 asymptomatic human immunodeficiency virus-infected individuals (HIV+) and 23 HIV-control subjects using a dual-task working memory paradigm. The HIV+ and HIV- groups showed an equivalent reduction in performance on both the primary task (visual vigilance) and the secondary task (letter span) when they were performed concurrently relative to when either task was performed alone. This result suggested normal CE functioning in these HIV+ subjects. In contrast, the HIV+ subjects had significantly longer response latencies on reaction time measures relative to the HIV- control group. These findings indicated that slowed processing in early stage HIV-infected individuals is not associated with a working memory deficit.

AIDS Dementia Complex↗

Evidence from two genetic syndromes for a dissociation between verbal and visual-spatial short-term memory.

Williams and Down syndromes, two genetic syndromes of abnormal neurodevelopment, are characterized by specific neuropsychological profiles and unique patterns of brain morphology. We find that the superior language ability of subjects with Williams syndrome is accompanied by significantly better performance on a verbal short-term memory task. Conversely, subjects with Down syndrome perform significantly better on a visual-spatial short-term memory task. This double dissociation provides neurogenetic evidence for the distinction between short-term storage for verbal and for visual-spatial stimuli.

Adolescent↗

Effects of practice of serial tests of attention in healthy subjects.

The effects of practice on the serial performance of auditory and visual attention tasks were investigated in 10 healthy volunteers tested at 2 to 4 weekly intervals over eight test sessions using a battery of psychometric tests. Subjects as a group showed an ability to significantly (p = .05) improve their performances over time on all tests except for the Simple Reaction Time and Symbol Digit Modalities Test, the latter demonstrating a trend towards improvement (p = .07). Improvement when it occurred was almost uniformly linear and on tests such as the Pegboard and Stroop, was still discernable at the eighth session. On tests such as Paced Visual Serial Addition Task, floor effects were noted after five sessions and no further improvement was possible. In general, younger subjects tended to make fewer errors, perform quicker and improve for longer periods than their older counterparts. The results indicate that on tests of attention, healthy subjects have the ability to significantly improve performance with practice and this may extend over as many as eight discrete test sessions. The implications for neuropsychological research are discussed.

Adult↗

Age differences in academic achievement in high-functioning autistic individuals.

A battery of psychoeducational tests was administered to samples of high-functioning (IQ > 70) autistic subjects and normal controls. A previous psychoeducational study indicated the presence of preserved procedural and mechanical academic skills accompanied by impaired comprehension and interpretive skills in high-functioning autistic individuals. The present findings indicate that this psychoeducational pattern also has a developmental aspect. Younger (< 13 years) autistic subjects performed as well or better than younger controls on psychoeducational measures of mechanical and procedural skills, and on some complex, interpretive tasks. However, they performed more poorly than controls on tasks that involve following complex linguistic instructions. Younger autistic subjects and controls did not differ significantly from each other on interpretive tasks, while the older austic subjects did significantly more poorly than the older controls on such tasks. The findings are discussed in terms of early success, but subsequent decline, in the course of academic functioning in autism.

Adolescent↗

Effects of aging and of Alzheimer's disease on verbal memory.

This study aimed to define the verbal memory profiles of very old normal subjects and subjects with Alzheimer's Disease, and to identify verbal memory indices having the highest discriminant power. Forty-three old normal subjects (mean age = 71 years, SD = 3, range = 65-75), 39 very old normal subjects (mean age = 81 years, SD = 4, range = 76-87), and 45 Alzheimer's patients (mean age = 70 years, SD = 5, range = 59-78) received the Rey test of verbal memory and the WAIS-R Digit Span forward and backward. All but one of the indices could distinguish very old from Alzheimer's subjects. A discriminant analysis disclosed a verbal memory profile of Alzheimer type in 15.4% of the very old group and of very old type in 16.2% of the Alzheimer's patients. Rate of forgetting, immediate and delayed Rey indices, and the true positive responses were, in decreasing order, the main determinants of the discriminant function. Thus, all of the components of verbal memory are differently affected by aging and Alzheimer's disease and contribute to define individual verbal memory profiles.

Aged↗

Calculation and number processing in mild Alzheimer's disease.

Calculation and number processing abilities in 17 patients suffering from a mild form of dementia of Alzheimer's type (DAT) were studied by means of a standardized multitask assessment battery, the EC301 (Deloche et al., 1994). Patients were selected from a larger sample by using a specific visuo-perceptive task to control the confounding effects of deficits in analysing digit serial order. Language and memory skills were evaluated by means of standardized testing procedures. The EC301 overall score showed impaired performance in 12 cases. Calculation and number processing scores were highly correlated with Mini-Mental State Examination and language performance. However, multiple single-case analyses indicated heterogeneous patterns of preserved/impaired abilities with respect to the three cognitive areas under investigation (calculation, memory, and language) and to the different components of the calculation and number processing system.

Aged↗

Everyday memory following traumatic brain injury.

Residual memory deficits may represent a problem to the everyday functioning of a large number of people, including those who have sustained traumatic brain injury (TBI). The present exploratory study sought to investigate the interrelationships between subjective memory reports, performance on traditional memory tests, and performance on tests of prospective memory. These interrelationships were contrasted between a group of 24 adults who had sustained TBI and a group of 24 matched control subjects. Prospective memory was hypothesized to be indicative of everyday memory functioning. The results provided preliminary evidence that prospective memory tests are sensitive to TBI-related neurological impairment and, in comparison to traditional tests, may be better indicators of functional memory capacity. This pattern was particularly true for control subjects, possibly because TBI subjects had difficulties in evaluating their memory functioning.

Activities of Daily Living↗

Dissociable lexical and phonological influences on serial recognition and serial recall.

The impact of the lexicality of memory items on memory performance was compared in two paradigms, serial recall and serial recognition. Experiments 1 to 3 tested 7- and 8-year-old children. Memory accuracy was only mildly impaired in lists containing nonwords compared with words in a serial recognition task involving judgments of whether the items in two sequences were in the same order (Experiment 1), although a substantial advantage for word over nonword items from the same stimulus pool was found in serial recall (Experiment 2). A stronger influence of lexicality on serial recall than serial recognition was further demonstrated in Experiments 3A and 3B, and in 4A and 4B using adult participants. These experiments also established comparable degrees of sensitivity to the phonological similarity of the memory sequences in the two paradigms. The phonological similarity effect in serial recall was found to arise from increased phoneme order errors, whereas the lexicality effect was due principally to the greater frequency of phoneme identity errors for nonwords. It is proposed that the lexicality effect originates in the redintegration of item information just prior to recall, and that this process is largely bypassed in serial recognition.

Adult↗

Processing and storage in working memory span.

Two experiments are reported that address theoretical assumptions as to the nature of working memory involved in working memory span tasks (Daneman & Carpenter, 1980). Experiment 1 used a version of the sentence span task, and Experiment 2 combined arithmetic verification with recall of presented words. In each experiment, working memory processing span was assessed independently of temporary storage span prior to their combination. Combined task performance under high demand for each component resulted in substantial residual performance for both task elements, particularly in Experiment 2. The results do not challenge the utility of the sentence span task as a measure of on-line cognition, but they raise concerns as to how resource might be allocated to processing and storage elements of the task within a single flexible resource pool, or between different resources of a multiple component working memory system. Although both models lack predictive power regarding resource allocation in these tasks, the multiple resource model appears to offer the better account.

Adult↗

Inverting the modality effect in serial recall.

Differences in recall ability between immediate serial recall of auditorily and visually presented verbal material have traditionally been considered restricted to the end of to-be-recalled lists, the recency section of the serial position curve (e.g., Crowder & Morton, 1969). Later studies showed that--under certain circumstances--differences in recall between the two modalities can be observed across the whole of the list (Frankish, 1985). However in all these studies the advantage observed is for recall of material presented in the auditorily modality. Six separate conditions across four experiments demonstrate that a visual advantage can be obtained with serial recall if participants are required to recall the list in two distinct sections using serial recall. Judged on a list-wide basis, the visual advantage is of equivalent size to the auditory advantage of the classical modality effect. The results demonstrate that differences in representation of auditory and visual verbal material in short-term memory persist beyond lexical and phonological categorization and are problematic for current theories of the modality effect.

Adult↗

Selective interference with verbal short-term memory for serial order information: a new paradigm and tests of a timing-signal hypothesis.

Many recent computational models of verbal short-term memory postulate a separation between processes supporting memory for the identity of items and processes supporting memory for their serial order. Furthermore, some of these models assume that memory for serial order is supported by a timing signal. We report an attempt to find evidence for such a timing signal by comparing an item probe task, requiring memory for items, with a list probe task, requiring memory for serial order. Four experiments investigated effects of irrelevant speech, articulatory suppression, temporal grouping, and paced finger tapping on these two tasks. In Experiments 1 and 2, irrelevant speech and articulatory suppression had a greater detrimental effect on the list probe task than on the item probe task. Reaction time data indicated that the list probe task, but not the item probe task, induced serial rehearsal of items. Phonological similarity effects confirmed that both probe tasks induced phonological recoding of visual inputs. Experiment 3 showed that temporal grouping of items during list presentation improved performance on the list probe task more than on the item probe task. In Experiment 4, paced tapping had a greater detrimental effect on the list probe task than on the item probe task. However, there was no differential effect of whether tapping was to a simple or a complex rhythm. Overall, the data illustrate the utility of the item probe/list probe paradigm and provide support for models that assume memory for serial order and memory for items involve separate processes. Results are generally consistent with the timing-signal hypothesis but suggest further factors that need to be explored to distinguish it from other accounts.

Adult↗

Irrelevant sound disrupts speech production: exploring the relationship between short-term memory and experimentally induced slips of the tongue.

To explore the relationship between short-term memory and speech production, we developed a speech error induction technique. The technique, which was adapted from a Japanese word game, exposed participants to an auditory distractor word immediately before the utterance of a target word. In Experiment 1, the distractor words that were phonologically similar to the target word led to a greater number of errors in speaking the target than did the dissimilar distractor words. Furthermore, the speech error scores were significantly correlated with memory span scores. In Experiment 2, memory span scores were again correlated with the rate of the speech errors that were induced from the task-irrelevant speech sounds. Experiment 3 showed a strong irrelevant-sound effect in the serial recall of nonwords. The magnitude of the irrelevant-sound effects was not affected by phonological similarity between the to-be-remembered nonwords and the irrelevant-sound materials. Analysis of recall errors in Experiment 3 also suggested that there were no essential differences in recall error patterns between the dissimilar and similar irrelevant-sound conditions. We proposed two different underlying mechanisms in immediate memory, one operating via the phonological short-term memory store and the other via the processes underpinning speech production.

Acoustic Stimulation↗

Phonological similarity effects in verbal complex span.

Phonological similarity effects were used to assess the role of acoustic coding in verbal complex span, a processing-plus-storage measure found to correlate significantly with aspects of complex cognition. Three experiments demonstrated consistent effects of phonological similarity on listening span. These effects appeared relatively insensitive to manipulations of task materials (Experiment 1) and differences in processing task demands (Experiments 2 and 3). The results were interpreted as reflecting a significant role for the phonological loop in supporting verbal complex span and a multicomponent view of working memory, as tapped by these tests. Phonological similarity did not significantly interact with aspects of the tasks varied across Experiments 1 to 3, suggesting a relative robustness of the effect. However, variation in the phonological similarity effect sizes across Experiments 1 to 3 supports the suggestion that task demands and characteristics have the potential to disrupt the phonological similarity effect and, by implication, the reliance on a phonological code.

Adolescent↗

Lexical and semantic influences on item and order memory in immediate serial recognition: evidence from a novel task.

Previous studies have reported that, in contrast to the effect on immediate serial recall, lexical/semantic factors have little effect on immediate serial recognition. This has been taken as evidence that linguistic knowledge contributes to verbal short-term memory in a redintegrative process at recall. Contrary to this view, we found that lexicality, frequency, and imageability all influenced matching span. The standard matching span task, requiring changes in item order to be detected, was less susceptible to lexical/semantic factors than was a novel task involving the detection of phoneme order and hence item identity changes. Therefore, in both immediate recognition and immediate serial recall, lexical/semantic knowledge makes a greater contribution to item identity than to item order memory. Task sensitivity, and not the absence of overt recall, may have underpinned previous failures to show effects of these variables in immediate recognition. We also compared matching span for pure and unpredictable mixed lists of words and nonwords. Lexicality had a larger impact on immediate recognition for pure than for mixed lists, in line with findings for immediate serial recall. List composition affected the detection of phoneme but not item order changes in matching span; similarly, in recall, mixed lists produce more frequent word phoneme migrations but not migrations of entire items. These results point to strong similarities between immediate serial recall and recognition. Lexical/semantic knowledge may contribute to phonological stability in both tasks.

Adolescent↗

Prerequisites for lack of age differences in memory performance.

Free recall performance of young and old adults was examined in three memory tasks: acts carried out by the subjects (subject-performed tasks or SPTs), sentences with imagery instructions, and sentences. The subjects were presented with the same verbal information in all three tasks. No age differences were observed on free recall of SPTs, whereas typical aging effects were obtained on free recall of the other tasks. This way the data from a previous study of no age effects on SPT recall were replicated. A hypothesis about imagery as a critical factor for the lack of age differences on SPT recall gained no support. Two main concepts were proposed to account for the data: Compensation among the elderly by means of the multimodal and rich properties of SPTs, and a superior ability for a spontaneous recoding of verbal information among young adults. The results were also discussed in relation to a presumption of memory tasks as varying in attentional demands.

Adolescent↗