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2. COGNITIVE PSYCHOLOGY
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This is the area of the unit's greatest theoretical involvement. While the core of the work is covered under Project 1, Projects 9, 11, 13, 18 and 25 all represent extensions of this basic area. It is a difficult field to categorise since the same underlying theoretical concepts underpin a wide range of studies on topics as diverse as arithmetic and face recognition, amnesia and the design of government forms.
2.1 Memory (Baddeley, Barnard, Byrne, Hitch, Hull, Lewis, Moar, Morton, K. Patterson, Woodhead)
The study of memory has remained a central theoretical interest; in addition there has been a growing concern with the role of memory in other tasks. Examples include the role of precategorical acoustic storage in speech perception (13;125 ; 126> 132)t tne role of a short-term working memory in reading (4; 5) and mental arithmetic (70; 75) and the role of semantic memory in tasks such as recalling recipes (130) or interacting with a computer, or indeed a government form (221; 223), or a road sign (225).
The concept of working memory has been elaborated by Baddeley and Hitch and continues to develop. At present a distinction is made between a central attentional system which also has memory storage capabilities, and two peripheral memory systems, one involved in subvocal rehearsal, the other in visual imagery. The applications of the model will be discussed in more detail in the sections on reading and on arithmetic. This approach to memory is discussed and compared to alternative currently held views of memory in a number of chapters and papers (1; 5; 8; 12; 72).
While the bulk of our work on memory has used verbal materials, there has been a growing interest in non-verbal and in particular visuo-spatial memory. In addition to work on face recognition (see p.lj ), both Hitch and Baddeley are currently exploring the concept of a spatial working memory, and Moar (120) has carried out an extensive series of studies on mental maps. To do so he devised a new method of externalising a subject's representation of space in long-term memory which is analogous to the triangulation procedure used in surveying. He has already explored spatial representation over a range of different scales, from that of an individual building to concepts of the world, showing that internal representations are virtually always topologically appropriate, but may be non-Euclidean.
The unit's interest in the design of codes has continued and work by Hull has resulted in a number of papers on specific problems of alpha¬numeric codes (80; 82; 83) together with an article summarising what is known and providing ground rules for the code designer (81).
Work by Baddeley on amnesia has continued, jointly with Dr. Brooks of the Southern General Hospital, Glasgow. Progress has been steady but rather slow due to lack of good patients and the complexities of collaborating at a distance. We have however continued to explore the range of learning tasks on which amnesic performance is not impaired (22). The pattern of results suggests that the amnesic's problem may not be in learning, so much as in knowing what he has learnt. Hence our subjects are able to utilise newly learnt information in order to do a jigsaw puzzle, perform a skill or re-order a jumbled sentence, but are grossly defective if required to recall the relevant information explicitly.
Closed head injury and memory (Baddeley, Harris, Sunderland)
Closed head injury involves large numbers of relatively young patients and present major rehabilitation problems. Conventional psycho¬metric testing suggests that memory impairment is common. However, little is known either about the detailed nature of the memory defect, or about its implications for the patient's ability to cope with everyday life. A new project is being carried out in collaboration with the department of Neurology and Neurosurgery at Addenbrooke's Hospital; it aims to study i sit.- relationship between performance on laboratory tests of memory and the practical difficulties raised by memory defect. We hope to explore the implications of this for rehabilitation and develop techniques to help the patient cope with defective memory.
2.2 Reading (Baddeley, Barnard, Conrad, Lewis, Marcel, Morton, K. Patterson, Wilcox, Wright)
It is very difficult to summarise work on reading for two reasons: first, the heading covers everything from perceiving printed stimuli to comprehension and speech; secondly, different people have approached different aspects of reading and have shed light on the processes when using a variety of reading tasks for different purposes. Perhaps the best way of organising the work is in terms of "stages" of the process.
2.2.1 Lexical Factors.
The internal lexicon is a hypothetical 'stage' where words are stored as an interface (i) between input and semantics and (ii) between input or semantics and output codes (phonological ortho¬graphic). Three aspects of this have been investigated.
(a) Logogen Model. This model, originally developed by Morton to deal with word recognition has recently been applied to the acquisition of phonology in children (138) and to certain kinds of dyslexia (143; 147). The model itself has become more specific - the unit of recognition being shown to be a morpheme not a word (142) - and processes specific to auditory and visual language input being separated from each other and from an output system (129).
(b) The automatic nature of access. Marcel (107) has shown tnat lexical access is achieved automatically, even when subjects donot
know a word has been presented. The technique used is that of backward pattern-masking and is proving useful in other areas.
(c) Access Codes. It has long been debated whether a direct visual route to the lexicon exists, or whether the route is indirect, involving conversion of a graphemic to a phonological code. In the course of K. Patterson's work with aphasic patients with a reading impairment, strong evidence has been presented (143; 147) that both routes exist normally, the phonological one being impaired in the patients. It is plausible that the lack of such a route is what impairs the acquisition of reading in deaf children as noted by Conrad (44). However Patterson and Marcel's paper (147) suggests direct visual access in the skilled reader.
(d) How many lexicons? In a review of their work on normal and aphasic people Marcel and Patterson (109) suggested the existence of both an input and an output lexicon, one converting sensory input to semantics, the other converting semantics to speech. Morton (129) has completed a set of experiments which look for facilitation by one stimulus of the naming of another. These experiments suggest not only that input and output lexicons should indeed be separated but also that separate input lexicons exist for each modality (auditory and visual).
In addition to this, Marcel and Patterson (109) have conducted a series of experiments on the representation of different word classes in the two cerebral hemispheres. They suggest that while the output lexicon is restricted to the left hemisphere, input lexicons exist in both hemispheres. These theoretical developments are in line with current neuropsychological ideas and should allow finer grain analyses of reading.
(e) Post-lexical Factors. Baddeley and Lewis have investigated the role of post-lexical "working memory" in reading. Baddeley has suggested (4) that the articulatory loop is used as a holding device in decoding by people learning to read and also that in fluent readers it is what preserves word order in understanding sentences.
The nature of the code used in this system appears to be important for spelling. Marcel (106) has isolated groups of children, adult illiterates and aphasic patients who appear to rely on an acoustic/ articulatory code rather than a phonological one. This leads to predictable errors in the perception and production of consonant clusters.
2.3 Pictographic Instructions (Barnard, Marcel)
This work was undertaken by Barnard and Marcel for the Post Office but is currently motivated by both theoretical and applied interests. The aim is to explore non-verbal means or giving instructions for the use of equipment. Its target is a high level input to design for inter¬national usage, populations limited ir. language and literacy as well as improvements for normal users. Its theoretical potential is a non-linguistic route to semantics, cognitive structures (e.g. notions of cause and effect) and problem-solving strategics.
We have constructed a flexible piece of experimental equipment which can simulate different real-life technologies. Using this, studies of pictographic sequences of instructions have shown that people presuppose that changes in the state of a machine are brought about only by actions of the operator. This led to mistakes in interpreting machine delays where a change in machine state occurred without further action by the operator. This presupposition could also help to account for the finding that performance was better when following instructions segmented into actions and their effects than when the instructions were "phrased" as signals for an appropriate action (17, 108. In general these studies indicate that the design of graphic instructions needs to take account of how people conceive of equipment functioning and how they use instructions when interacting with equipment.
2.4 Research on Second Language Performance (Long, in collaboration with E. Harding, Linguistics Dept., University of Cambridge).
Performance on a task involving a second language rather than a first or mother tongue depends on both the proficiency of a person in the second language, and the linguistic and psychological difficulty of the task.
The first study by Long and Harding (103) showed both a general and a selective impairment in second language performance on a summary task. A second part of the study showed an impairment as a function of psychological factors (mostly involving memory) even when people knew the vocabulary and syntax. These results indicate that the second language deficit is multiply determined. Future research will examine in more detail the particular processing stages responsible for the second language deficit and attempt to model the relations between a person's two language systems.
2.5 Psychology of Language and Speech (Barnard, Buxton, Hammersley, Long,
Marcel, Marcus, Morton, Simmonds, Skinner, Wright)(Project No. 13)
2.5.1 Language Language understanding has been studied in a variety of contexts.
Research by Wright and Wilcox (226) on the comprehension of sentences has shown that the difficulty in interpreting a sentence may be critically dependent upon contextual factors which therefore need to be included alongside linguistic considerations when developing psychological models of language comprehension. Wright and Wilcox (227) have also shown that the order in which items are mentioned in a sentence has consequences for the way in which emphasis is allocated by the reader and for the way in which people represent the information in ah instruction prior to carrying it out. Both these consequences of order of mention interact with other aspects of sentence structure. Similar interactions were found when comparing the assignment of articles in active and passive sentences (224). Explanations of these interactions are being developed.
2.5.2 Speech
Morton and Chambers have shown that speech sounds and non-speech sounds are processed by separate systems prior to categorisation. Uhen we listen in continuous speech for particular sounds in words (such as an initial b), Morton and Long (134) showed that we can only do so after categorisation into words.
2.5.3 P-Centres
The general theoretical notion of a Perceptual or Production Centre of an event has been introduced by Morton, Marcus and Frankish (135). Its initial application has been, in terms of determining the factors which lead to rhythmic regularity in a sequence of words and in forcing a reconsideration of the notion of simultaneity in dichotic listening.
2.6 Design of Information (Barnard, Wilcox, Wright)(Project No. 9)
This project examines many of the psychological factors influencing how easily people can understand written information. The approach has been heterogeneous rather than uniform, since different types of information raise quite different theoretical and methodological problems (23). Aspects of both the language used and the physical layout of the information have been considered for materials as diverse as questions on forms, picto-graphic representation of instructions for machinery and tabulations of numerical data (33). It has been shown by Barnard, Wright and Wilcox that some of the current practices on forms actually reduce the legibility of the answers given (19, 20) or are more error prone than alternatives (220; 223). Errors may also increase when the form-filler is constrained by the requirements of an electronic data processing system and care needs to be taken to ensure that maximum use is made of software facilities to reduce the problems for the form-filler. Research on the comprehension of texts longer than single questions or single sentences has highlighted a number of problems and measuring technique are being developed to study the more global aspects of text comprehension.
The accuracy with which people use a numerical table may be determined by psychological aspects of language. When comparing a value with that in a table, people were faster and more accurate in reaching Yes/No decisions about whether the value was more than that shown in the table than they were at reaching decisions about whether the value was less than that in the table (221). Decisions, often involving conjunctions and disjunctions, also have to be made in order to locate the cell in a table. It was found that requiring fewer decisions resulted in better performance (216;. Conjunctive and disjunctive decisions are also made by examination candidates interpreting the rubric for a particular paper (e.g. answer five questions doing at least two and not more than four from any one section). Comparisons among alternative rubric formats showed that simple language forms were not always best (214). Again people's presuppositions may have been one of the critical factors. Reviews of various aspects of the design of information have been published. These have dealt with the use of flowcharts (213). the design of forms (215; 223), the presentation of technical information (217; 218) and the relation between different kinds of research on comprehension (219).
2.7 Linguistic and Cognitive Aspects of the Interface in the Use of Interactive Computing Systems as Problem Solving Aids (Barnard, Hammond, Long, Morton, Ottley)(Project No. 23)
This project classification was brought into being to cover a collaborative project with the IBM United Kingdom Scientific Centre. The project actually started in August 1977. The previous two years involved some exploratory research, defining appropriate issues for the project itself and negotiating the formal contract between MRC and IBM.
The exploratory research examined two complementary problems associated with the organisation of information presented at a terminal to naive users of interactive computing systems (18). The first problem concerned the appropriateness of alternative organisations for listings of information on a display. Alphabetic organisations were compared with alternatives based on the conceptual structure of the information itself (e.g. by category or spatial location). Potential applications cover a wide range of general data retrieval systems (e.g. the Post Office's viewdata system,orCEFAX) or more specific data retrieval systems (e.g. stocktaking systems). The second problem concerned the appropriateness of alternative organisations of the digits 0 through 9 presented on computer displays enabling direct entry of information via a lightpen or proximity device. Linear, keypad and cash register arrangements were contrasted for entry of numerical strings (such as personal income)(101).
Following discussions with IBM the project itself was focused on the nature of simple computer languages which might be appropriate for users of interactive data base enquiry systems who were not themselves computer experts. A blueprint for an approach to the problem was explored (133), and initial experiments on the project have examined (a) the attitudes of a sample of potential users of such systems and (b) the influence of natural language on the use of instructional commands typically found in existing computer systems.
2.8 Psychological Aspects of Numerical Information Processing (Hitch) (Project No. 11)
The concept of a short-term "working memory" was applied by Hitch to understanding the nature of elementary written and mental arithmetic. The performance of arithmetical skills was shown to depend on the temporary storage of information which is rapidly forgotten. In mental arithmetic this is a particularly severe problem: virtually all errors are due to forgetting rather than faulty arithmetic per se. Further, different calculation strategies place different patterns of demand on memory and arc not equally efficient. These results are related to the general concept of working memory (70; 72) and are used to test a mathematical model of addition (75). The next phase of this research is to investigate how the stored information is coded, and will include the use of selective interference techniques to explore the role of verbalisation and visual imagery.
Applied work has included an extensive 'in-depth' survey of the numerical abilities of young recruits to industry at trainee level (74). Contrary to what would be expected on the basis of general public opinion, the 'four rules' of ordinary arithmetic were performed reasonably well, and there was far greater difficulty with even elementary calculations involving decimals and fractions.
More recent work has examined the efficiency of adding columns of figures using a pocket calculator (77). It turns out that pencil and paper methods are as fast as using the calculator for naive users, but that the calculator is more accurate for all but the shortest columns. Experienced users were both quicker and more accurate using the calculator than with pencil and paper.
Future work in the general area will continue to expand the core of theoretical work, adding more to the links with other areas of cognitive psychology, and using it to support a range of applied investigations. Of the latter, the search for factors improving the comprehensibility of numerical information looks particularly promising at this stage.