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Biomedical subjects

A Baddeley

Publications and source records attributed to A Baddeley.

8 recordsLinked to original sources
PubMed1992

Working memory.

The term working memory refers to a brain system that provides temporary storage and manipulation of the information necessary for such complex cognitive tasks as language comprehension, learning, and reasoning. This definition has evolved from the concept of a unitary short-term memory system. Working memory has been found to require the simultaneous storage and processing of information. It can be divided into the following three subcomponents: (i) the central executive, which is assumed to be an attentional-controlling system, is important in skills such as chess playing and is particularly susceptible to the effects of Alzheimer's disease; and two slave systems, namely (ii) the visuospatial sketch pad, which manipulates visual images and (iii) the phonological loop, which stores and rehearses speech-based information and is necessary for the acquisition of both native and second-language vocabulary.

Brain↗
PubMed1991

The two-component hypothesis of memory deficit in Alzheimer's disease.

Becker (1988) has argued that Alzheimer's disease is particularly characterised by a combination of amnesic and dysexecutive deficits. He has supported this hypothesis by identifying patients who represent a relatively pure example of each of these. We describe a search for similarly pure patients in a sample of 55 carefully selected Alzheimer cases. We succeed in identifying one case each of relatively pure amnesia and relatively pure dysexecutive syndrome. We also, however, find cases of predominant STM deficit, as well as cases with defective visual but not verbal memory, and cases of the converse pattern. These cases do not seem to reflect simple random variation in the data, since less theoretically coherent patterns of symptoms are not found in this pure form. We conclude that AD can give rise to relatively specific cognitive deficits during its early stages, but that these do not necessarily argue for Becker's two-component interpretation of the cognitive deficit in Alzheimer's disease.

Aged↗
PubMed1990

Assessing everyday memory in patients with dysphasia.

An assessment of the current memory status of patients referred for speech therapy is rarely provided, but may be useful in indicating whether there is memory loss in addition to language deficits. Failure to progress during treatment could be due to failure to remember the content of the previous sessions. Most existing memory tests are unsuitable for assessing subjects with dysphasia. For that reason we sought to modify the Rivermead Behavioural Memory Test (RBMT: Wilson, Cockburn & Baddeley, 1985), which was developed to measure the existence and extent of everyday memory problems and which contains both verbally and non-verbally mediated items. The study described here, based on a sample of 176 brain-injured patients, showed that a mild to moderate language deficit did impair performance on the RBMT. The influence was found to be limited to a subset of verbal memory items. A shortened version of the test was developed and shown to be sensitive to memory deficits and insensitive to the effects of dysphasia. Revised norms for this version of the test are provided. These should enable an estimate to be made of the presence and magnitude of memory deficits in dysphasic patients, allowing treatment to be optimized.

Adolescent↗
PubMed1989

The development and validation of a test battery for detecting and monitoring everyday memory problems.

This paper describes the Rivermead Behavioural Memory Test (RMBT)-a short test of everyday memory problems with four parallel forms. It was administered to 118 control subjects aged between 16-69 years with a mean IQ of 106 (range 68-136). The limit of normal performance was established on this group and cut-off points were determined for individual components of the test. The test was also given to 176 brain-damaged people and its validity assessed both by correlating RMBT scores to performance on existing tests, to subjective ratings from patients and carers and to observation by therapists of memory lapses. Validity, parallel form and interrater reliability all proved to be high. It is concluded that the RBMT is a short, reliable, and valid test of everyday memory problems.

Adolescent↗
PubMed1988

Measuring memory.

Three broad approaches to the measurement of memory functioning will be described. The first of these involves using memory as a general indicator of any dysfunction in the central nervous system. This approach will be illustrated using Sternberg's short-term memory scanning paradigm. Its strengths are that such tests are often very sensitive, but they are often very difficult to interpret both theoretically and in practical terms. A second approach is to use a range of tasks selected so as to tap different aspects of human memory. Such an approach is of considerably more theoretical interest, and is discussed in more detail by Eysenck (this volume). Its weaknesses are that theories of memory are still changing relatively quickly, and that mapping such results onto memory outside the laboratory is often complex. A third approach is to attempt a more direct measure of everyday memory. The use of questionnaires for this purpose will be critically discussed, and a new test of everyday memory will be described. This test, the Rivermead Behavioural Memory Test, correlates well with observations of memory lapses in patients, and appears to offer a promising new line of development.

Humans↗
PubMed1988

Semantic, episodic, and autobiographical memory in a postmeningitic amnesic patient.

This study is concerned with the semantic and episodic memory performance of a highly intelligent and intellectually unimpaired patient, K.J., who became amnesic following meningitis. Although densely amnesic he showed unimpaired performance on tests of vocabulary and verbal fluency, while both speed and accuracy on semantic category judgment and sentence verification tests are unimpaired. It is concluded that semantic memory performance may be intact despite dense amnesia. However, this does not necessarily imply separate semantic and episodic memory systems. K.J. showed an impaired capacity for registering new material in semantic memory, and apparently normal autobiographical memory for events occurring well before his illness. The simplest interpretation of our results would therefore appear to be in terms of the sparing of old and overlearned memories rather than the specific preservation of semantic memory.

Amnesia↗
PubMed1986

The unattended speech effect: perception or memory?

Broadbent (1983) has suggested that the influence of unattended speech on immediate serial recall is a perceptual phenomenon rather than a memory phenomenon. In order to test this, subjects were required to classify visually presented pairs of consonants on the basis of either case or rhyme. They were tested both in silence and against a background of continuous spoken Arabic presented at 75 dB(A). No effect of unattended speech was observed on either the speed or accuracy of processing. A further study required subjects to decide whether visually presented nonwords were homophonous with real words. Again, performance was not impaired by unattended speech, although a clear effect was observed on an immediate serial memory task. Our results give no support to the perceptual interpretation of the unattended speech effect.

Adult↗