Biomedical subjects

Alan D Baddeley

Publications and source records attributed to Alan D Baddeley.

15 recordsLinked to original sources

PubMed2006

Using semantic memory to boost 'episodic' recall in a case of developmental amnesia.

We report two experiments that investigated factors that might boost 'episodic' recall for Jon, a developmental amnesic whose episodic memory is gravely impaired but whose semantic memory seems relatively normal. Experiment 1 showed that Jon's recall improved following a semantic study task compared with a non-semantic study task, as well as following four repeated study trials compared with only one. Experiment 2 additionally revealed that Jon's recall improved after acting compared with reading action phrases at study, but only if the phrases were well integrated semantically. The results provide some support for the hypothesis that Jon's 'episodic' recall depends on the extent to which he is able to retrieve events using semantic memory.

Adult↗

PubMed2006

Is the binding of visual features in working memory resource-demanding?

The episodic buffer component of working memory is assumed to play a role in the binding of features into chunks. A series of experiments compared memory for arrays of colors or shapes with memory for bound combinations of these features. Demanding concurrent verbal tasks were used to investigate the role of general attentional processes, producing load effects that were no greater on memory for feature combinations than for the features themselves. However, the binding condition was significantly less accurate with sequential rather than simultaneous presentation, especially for items earlier in the sequence. The findings are interpreted as evidence of a relatively automatic but fragile visual feature binding mechanism in working memory. Implications for the concept of an episodic buffer are discussed.

Analysis of Variance↗

PubMed2006

The selective disruption of spatial working memory by eye movements.

In the late 1970s/early 1980s, Baddeley and colleagues conducted a series of experiments investigating the role of eye movements in visual working memory. Although only described briefly in a book, these studies have influenced a remarkable number of empirical and theoretical developments in fields ranging from experimental psychology to human neuropsychology to nonhuman primate electrophysiology. This paper presents, in full detail, three critical studies from this series, together with a recently performed study that includes a level of eye movement measurement and control that was not available for the older studies. Together, the results demonstrate several facts about the sensitivity of visuospatial working memory to eye movements. First, it is eye movement control, not movement per se, that produces the disruptive effects. Second, these effects are limited to working memory for locations and do not generalize to visual working memory for shapes. Third, they can be isolated to the storage/maintenance components of working memory (e.g., to the delay period of the delayed-recognition task). These facts have important implications for models of visual working memory.

Adolescent↗

PubMed2005

Differential constraints on the working memory and reading abilities of individuals with learning difficulties and typically developing children.

This study examined the factors that constrain the working memory span performance and reading ability of individuals with generalized learning difficulties. In the study, 50 individuals with learning difficulties (LD) and 50 typically developing children (TD) matched for reading age completed two working memory span tasks. Participants also completed independent measures of the processing and storage operations involved in each working memory span task and Raven's Coloured Progressive Matrices. The results showed that despite an equivalent level of working memory span, the relative importance of the constraints on working memory differed between the groups. In addition, working memory span was not closely related to word recognition or sentence comprehension performance in the LD group. These results suggest that the working memory span performance of LD and TD individuals may reflect different working memory limitations and that individuals with generalized learning difficulties may approach cognitive tasks in a qualitatively different way from that of typically developing individuals.

Child↗

PubMed2005

Mapping the developmental constraints on working memory span performance.

This study investigated the constraints underlying developmental improvements in complex working memory span performance among 120 children of between 6 and 10 years of age. Independent measures of processing efficiency, storage capacity, rehearsal speed, and basic speed of processing were assessed to determine their contribution to age-related variance in complex span. Results showed that developmental improvements in complex span were driven by 2 age-related but separable factors: 1 associated with general speed of processing and 1 associated with storage ability. In addition, there was an age-related contribution shared between working memory, processing speed, and storage ability that was important for higher level cognition. These results pose a challenge for models of complex span performance that emphasize the importance of processing speed alone.

Age Factors↗

PubMed2005

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↗

PubMed2004

Comprehension of spatial language terms in Williams syndrome: evidence for an interaction between domains of strength and weakness.

Individuals with Williams syndrome show an unusual neuropsychological profile, with relatively strong language abilities and impoverished visual and spatial abilities. Two studies are reported that examine the interaction between these two domains in Williams syndrome by assessing individuals' comprehension of spoken language with a spatial component. In a first study, the Test for Reception of Grammar (Bishop, 1983) was given to 32 individuals with Williams syndrome and to controls matched individually for total number of errors on the task. Individuals with Williams syndrome had particular problems when asked to comprehend sentences containing spatial prepositions, making significantly more errors on these items than control groups. A second study examined in more detail comprehension of sentences with spatial and non-spatial components, comparing the performance of 15 individuals with Williams syndrome and control groups matched for vocabulary ability. Individuals with Williams syndrome again showed impaired comprehension of spoken spatial terms. In contrast, they were unimpaired in comprehending utterances without a spatial component, with the exception of descriptions testing comprehension of non-spatial comparatives (lighter than and darker than). These results suggest that the spatial difficulties experienced by individuals with Williams syndrome may constrain language comprehension in certain circumstances. They also shed light on the ways in which spatial cognition may interact with language comprehension more generally.

Adolescent↗

PubMed2004

Retroactive effects of irrelevant speech on serial recall from short-term memory.

The authors report 5 serial-recall experiments. In 4 of the 5 experiments, they show that irrelevant sound (IS) has a retroactive effect on material already in memory. In Experiment 1, IS presented during a filled retention interval had a reliable effect on list recall. Four further experiments, 3 of which used retroactive IS, showed that IS continued to-have an effect on recall following a long, filled retention interval. Articulatory suppression during visual input was found to abolish the long-lasting, retroactive effect of IS, supporting the idea that IS affects the phonological-loop component of short-term memory. IS also, therefore, seems to affect a longer term memory system with which the loop interacts.

Cues↗

PubMed2004

Is there a specific executive capacity for dual task coordination? Evidence from Alzheimer's disease.

Three experiments compared groups of Alzheimer's disease (AD) patients and healthy older and younger participants on visuospatial tracking and digit sequence recall, as single tasks and performed concurrently. In Experiment 1, tasks were performed concurrently with very low demand relative to span. Only the AD patients showed a dual task deficit. In Experiment 2, single task demand was manipulated on each task from below span to above span for each individual. All groups showed the same performance reductions with increasing demand. In Experiment 3, demand on 1 task was constant, whereas demand on the concurrent task was varied. AD patients showed a clear dual task deficit but were no more sensitive than control groups to varying demand. Results suggest an identifiable cognitive resource for dual task coordination within a multiple component working memory system.

Adult↗

PubMed2004

Can reading accuracy and comprehension be separated in the Neale Analysis of Reading Ability?

BACKGROUND: The Neale Analysis of Reading Ability (NARA) (Neale, 1997) is widely used in education and research. It provides measures of reading accuracy (decoding) and comprehension, which are frequently interpreted separately. AIMS: Three studies were conducted to investigate the degree to which the NARA measures could be separated. SAMPLES: British 7- and 8-year-olds participated in Study 1 (N=114) and Study 2 (N=212). In Study 3, 16 skilled and less-skilled comprehenders were identified from the Study 2 sample. METHODS: Study 1: By investigating their contribution to silent reading comprehension, the independence of NARA decoding and comprehension scores was determined. Study 2: Decoding groups matched for listening comprehension were compared on the NARA comprehension measure, and population performance was compared across listening comprehension and NARA reading comprehension. Study 3: Comprehension groups were compared on ability to answer open-ended and forced-choice questions. RESULTS: Firstly, NARA comprehension performance depended on decoding, to the extent that children with high listening comprehension ability but low decoding ability attained low NARA comprehension scores. Secondly, 32% of children who attained low NARA comprehension scores exhibited high listening comprehension. Thirdly, comprehension groups differed when assessed with open-ended questions but not when assessed with forced-choice questions. CONCLUSIONS: The NARA can underestimate the comprehension ability of children with weak decoding skills and children who have some difficulty with open-ended questions. The decoding and comprehension measures of the NARA cannot be separated. These findings have important implications for the interpretation of the measures provided by the NARA, in education and research.

Aptitude↗

PubMed2003

The complexities of complex span: explaining individual differences in working memory in children and adults.

Two studies are presented that investigated the constraints underlying working memory performance in children and adults. In each case, independent measures of processing efficiency and storage capacity are assessed to determine their relative importance in predicting performance on complex span tasks,which measure working memory capacity. Results show that complex span performance was independently constrained by individual differences in domain-general processing efficiency and domain-specific storage capacity. Residual variance, which may reflect the ability to coordinate storage and processing, also predicted academic achievement. These results challenge the view that complex span taps a limited-capacity resource pool shared between processing and storage operations. Rather, they are consistent with a multiple-component model in which separate resource pools support the processing and storage functions of working memory.

Adult↗

PubMed2003

List composition and the word length effect in immediate recall: a comparison of localist and globalist assumptions.

Lists of short words usually are recalled better than lists of longer words in immediate recall tasks. Such word length effects might be explained by localist accounts, in which the length of each word in a list affects the recall of that word only, or by globalist accounts, in which the lengths of at least some words affect the recall of other words (e.g., Baddeley, 1986). In a recent localist account, Neath and Nairne (1995) proposed that the recall of each word depends on the likelihood that features within the word are contaminated within the memory representation. We tested this by presenting not only homogeneous lists of short and long words, but also mixed lists, and by including articulatory suppression on some trials. The short-word advantage depended on the composition of the list, ruling out a strictly localist approach. There appear to be several globalist influences on recall, including distinctiveness factors as well as phonological storage and articulation.

Adult↗

PubMed2002

Verbal short-term memory in Down syndrome: a problem of memory, audition, or speech?

The current study explored three possible explanations of poor verbal short-term memory performance among individuals with Down syndrome in an attempt to determine whether the condition is associated with a fundamental verbal short-term memory deficit. The short-term memory performance of a group of 19 children and young adults with Down syndrome was contrasted with that of two control groups matched for level of receptive vocabulary. The specificity of a deficit was assessed by comparing memory for verbal and visuo-spatial information. The effect of auditory problems on performance was examined by contrasting memory for auditorily presented material with that for material presented both auditorily and visually. The influence of speech-motor difficulties was investigated by employing both a traditional recall procedure and a serial recognition procedure that reduced spoken response demands. Results confirmed that individuals with Down syndrome do show impaired verbal short-term memory performance for their level of receptive vocabulary. The findings also indicated that this deficit is specific to memory for verbal information and is not primarily caused by auditory or speech-production difficulties.

Adolescent↗

PubMed2002

Concurrent performance of two memory tasks: evidence for domain-specific working memory systems.

Previous studies of dual-task coordination in working memory have shown a lack of dual-task interference when a verbal memory task is combined with concurrent perceptuomotor tracking. Two experiments are reported in which participants were required to perform pairwise combinations of (1) a verbal memory task, a visual memory task, and perceptuomotor tracking (Experiment 1), and (2) pairwise combinations of the two memory tasks and articulatory suppression (Experiment 2). Tracking resulted in no disruption of the verbal memory preload over and above the impact of a delay in recall and showed only minimal disruption of the retention of the visual memory load. Performing an ongoing verbal memory task had virtually no impact on retention of a visual memory preload or vice versa, indicating that performing two demanding memory tasks results in little mutual interference. Experiment 2 also showed minimal disruption when the two memory tasks were combined, although verbal memory (but not visual memory) was clearly disrupted by articulatory suppression interpolated between presentation and recall. These data suggest that a multiple-component working memory model provides a better account for performance in concurrent immediate memory tasks than do theories that assume a single processing and storage system or a limited-capacity attentional system coupled with activated memory traces.

Adult↗

PubMedDate not supplied

The relationship between short-term memory and working memory: complex span made simple?

This experiment addresses the question of what makes a working memory measure a good predictor of higher-level abilities. Verbal and visuospatial processing episodes were interleaved with distinct verbal and visuospatial storage episodes to form four complex span tasks. Although these measures were reliable predictors of reading and mathematics ability in children, they were no more predictive of these abilities than corresponding simple span tasks involving storage alone. However, when individual differences in storage ability and processing capacity were controlled for, residual variance in complex span performance was related to academic ability in some cases. These findings indicate that complex span tasks are multiply determined, and that differences in task structure can dramatically influence the relative importance of these multiple constraints and the predictive power of a complex span measure.

Child↗