Robert H. Logie

Working memory: The multiple-component model.

FIVE CENTRAL FEATURES OF THE MODEL (1) According to our view, working memory comprises multiple specialized components of cognition that allow humans to comprehend and mentally represent their immediate environment, to retain information about their immediate past experience, to support the acquisition of new knowledge, to solve problems, and to formulate, relate, and act on current goals. (2) These specialized components include both a supervisory system (the central executive) and specialized temporary memory systems, including a phonologically based store (the phonological loop) and a visuospatial store (the visuospatial sketchpad). (3) The two specialized, temporary memory systems are used to actively maintain memory traces that overlap with those involved in perception via rehearsal mechanisms involved in speech production for the phonological loop and, possibly, preparations for action or image generation for the visuospatial sketchpad. (4) The central executive is involved in the control and regulation of the working memory system. It is considered to play various executive functions, such as coordinating the two slave systems, focusing and switching attention, and activating representations within longterm memory, but it is not involved in temporary storage. The central executive in principle may not be a unitary construct, and this issue is a main focus of current research within this framework. (5) This model is derived empirically from studies of healthy adults and children and of brain-damaged individuals, using a range of experimental methodologies. The model offers a useful framework to account for a wide range of empirical findings on working memory.

Visuo-spatial Working Memory

Temporary Memory. Mental Representation. The Visual and the Spatial. Working Memory. Neuropsychology. Assumptions, Reconciliation and Theory Development.

Age-of-acquisition, imagery, concreteness, familiarity, and ambiguity measures for 1,944 words

Age-of-acquisition, imagery, concreteness, familiarity, and ambiguity measures for 1,944 words of varying length and frequency of occurrence are presented. The words can all be used as nouns. Intergroup reliabilities are satisfactory on all attributes. Correlations with previous word lists are significant, and the intercorrelations between measures match previous findings.

Dementia and working memory

This study explored the hypothesis that patients suffering from dementia of the Alzheimer type (DAT) are particularly impaired in the functioning of the Central Executive component of working memory, and that this will be reflected in the capacity of patients to perform simultaneously two concurrent tasks. DAT patients, age-matched controls and young controls were required to combine performance on a tracking task with each of three concurrent tasks, articulatory suppression, simple reaction time to a tone and auditory digit span. The difficulty of the tracking task and length of digit sequence were both adjusted so as to equate performance across the three groups when the tasks were performed alone. When digit span or concurrent RT were combined with tracking, the deterioration in performance shown by the DAT patients was particularly marked.

Components of fluent reading

Abstract Two experiments studied individual differences among normal adults in performance on the Nelson-Denny reading test to cast light on the processes involved in reading. Experiment 1 correlated reading comprehension with performance on the Daneman and Carpenter working memory span test, vocabulary, lexical decision with both homophonous and nonhomophonous nonwords, and Posners letter matching task, based on both physical and name matching. Working memory span proved to be a significant predictor as did lexical decision with nonhomophonous nonwords, letter name matching, and vocabulary. A derived measure indicating degree of phonological coding in lexical decision was only weakly correlated with comprehension while the physical name match difference on the Posner task was uncorrelated with reading performance. A second experiment explored further the working memory span task, comparing it with a nonlinguistic span test devised by Case. Kurland, and Goldberg based on memory and counting. While the verbal working memory measure again correlated significantly with comprehension, the counting measure was much more weakly related. As in Experiment 1, vocabulary also correlated significantly with comprehension. It is concluded that reading comprehension is dependent on a number of separable components including vocabulary, working memory, and a general lexical access process.

Counting on working memory in arithmetic problem solving

Mental calculation is an important everyday skill involving access to well-learned procedures, problem solving, and working memory. Although there is an active literature on acquiring concepts and procedures for mental arithmetic, relatively little is known about the role of working memory in this task. This paper reports two experiments in which dual-task methodology is used to study the role of components of working memory in mental addition. In Experiment 1, mental addition of auditorily presented two-digit numbers was significantly disrupted by concurrent random letter generation and, to a lesser extent, by concurrent articulatory suppression, but was unimpaired by concurrent hand movement or by presentation of irrelevant pictures. Although the number of errors increased with two of the dual tasks, the incorrect responses tended to be quite close to the correct answer. In Experiment 2, the numbers for addition were presented visually. Here again, random generation produced the largest disruption of mental arithmetic performance, while a smaller amount of disruption was observed for articulatory suppression, hand movement, and unattended auditorily presented two-digit numbers. The overall levels of performance were better and the absolute size of the disruptive effects shown with visual presentation was very small compared with those found for auditory presentation. This pattern of results is consistent with a role for a central executive component of working memory in performing the calculations required for mental addition and in producing approximately correct answers. Visuospatial resources in working memory may also be involved in approximations. The data support the view that the subvocal rehearsal component of working memory provides a means of maintaining accuracy in mental arithmetic, and this matches a similar conclusion derived from previous work on counting. The general implications for the role of working memory in arithmetic problem solving will be discussed.

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.

Visuo-spatial processing in working memory.

This paper reports four experiments designed to develop a simple technique for the study of visuo-spatial processing within the working memory framework (Baddeley and Hitch, 1974). Experiment 1 involved the matching of successively presented random matrix patterns, as a secondary visual suppression task. This was coupled with rote rehearsal or a visual imagery mnemonic for learning lists of concrete words presented auditorily. Although memory performance with matching dropped overall, the visual mnemonic was differentially affected. Experiment 2 removed the matching decision, with visual presentation of unattended patterns. There was no overall effect of the unattended material, but use of the visual mnemonic was significantly affected. Experiment 3 replicated this result with simpler plain coloured squares as the unattended material. In Experiment 4, for one group, the unattended material consisted of line drawings of common objects. For a second group, the lists of words for recall were presented visually, with or without unattended speech. The results suggested that unattended pictures disrupt use of a visual mnemonic, while unattended speech disrupts rote rehearsal. These results suggest that unattended visual material has privileged access to the mechanism(s) involved in short-term visuo-spatial processing and storage. They also suggest that use of a concurrent visual matching task or of unattended visual material may provide tractable techniques for investigating this aspect of cognitive function within the context of working memory.

Interference with visual short-term memory

Working memory (Baddeley and Hitch 1974) incorporates the notion of a visuo-spatial sketch pad; a mechanism thought to be specialized for short-term storage of visuo-spatial material. However, the nature and characteristics of this hypothesized mechanism are as yet unclear. Two experiments are reported which examined selective interference in short-term visual memory. Experiment 1 contrasted recognition memory span for visual matrix patterns with that for visually presented letter sequences. These two span tasks were combined with concurrent arithmetic or a concurrent task which involved manipulation of visuo-spatial material. Results suggested that although there was a small, significant disruption by concurrent arithmetic of span for the matrix patterns, there was a substantially larger disruption of the letter span task. The converse was true for the secondary visuo-spatial task. Experiment 2 combined the span tasks with two established tasks developed by Brooks (1967). Span for matrix patterns was disrupted by a visuo-spatial task but not by a secondary verbal task. The converse was true for letter span. These results suggest that the impairment in short-term visual memory resulting from secondary arithmetic reflects a small general processing load, but that the selective interference due to mode of processing is by far the stronger effect. Results are interpreted as being entirely consistent with the notion of a specialized visuo-spatial mechanism in working memory.

The Inner Eye and the Inner Scribe of Visuo-spatial Working Memory: Evidence from Developmental Fractionation

An experiment is reported which explored the possible dissociation between visual and spatial working memory in children. Children aged 5–6, 8–9 and 11–12 years were given a recognition memory test for visual patterns or for sequences of movements to targets. Memory for patterns was better than memory for movement sequences and this difference was largest in the eldest group, and larger in the middle group than in the younger group. In a contrasting condition, the same groups of children were tested using immediate recall rather than recognition. A similar advantage for visual pattern memory over movement sequence memory appeared, and again this difference became more prominent with the age of the children. The results are interpreted as supporting the fractionation of visuo-spatial working memory into a temporary visual cache for storing visual form and an inner scribe for temporary retention of spatial information.