Neuropsychological evidence of visual storage in short-term memory tasks

Auditory and visual presentation of verbal material were compared in a single patient having an auditory verbal S.T.M. deficit. A Peterson short-term forgetting experiment and an immediate memory span task are reported. Striking differences in performance related to modality of input were obtained. Auditory short-term forgetting was more rapid, whereas with visual presentation short-term decay functions were relatively normal. With visual presentation there was no evidence of acoustic confusion errors but there was some evidence of visual confusion errors. The findings are interpreted in terms of a separate post-perceptual visual S.T.M. system.     

Auditory-verbal short-term memory impairment and conduction aphasia

The specific impairment of performance on repetition tasks has classically been identified with conduction aphasia. It is argued that this impairment can be subdivided and a deficit in span performance distinguished from that of the reproduction of single words. An explanation of the span deficit in terms of auditory-verbal short-term memory is preferred to hypotheses involving disconnections or damage to order retention systems. It is shown that a short-term memory component is present in many patients previously classified as conduction aphasics.     

Reading without semantics

Analysis of the reading of a neurological patient (HTR) indicates that it is based on the operation of a relatively unimpaired phonological route. Quantitative investigations of type of error, reading speed and the effects of lexicality and spelling-to-sound regularity all support this conclusion. Spelling-to-sound regularity is shown to influence reading not only through regular words being better read than irregular, but also through mildly irregular words being better read than very irregular ones. A model is presented of the operation of the phonological route and of its progressive impairment in certain types of neurological disease.     

Hierarchical schemas and goals in the control of sequential behavior

Traditional accounts of sequential behavior assume that schemas and goals play a causal role in the control of behavior. In contrast, M. Botvinick and D. C. Plaut argued that, at least in routine behavior, schemas and goals are epiphenomenal. The authors evaluate the Botvinick and Plaut account by contrasting the simple recurrent network model of Botvinick and Plaut with their own more traditional hierarchically structured interactive activation model (R. P. Cooper & T. Shallice, 2000). The authors present a range of arguments and additional simulations that demonstrate theoretical and empirical difficulties for both Botvinick and Plaut's model and their theoretical position. The authors conclude that explicit hierarchically organized and causally efficacious schema and goal representations are required to provide an adequate account of the flexibility of sequential behavior.     

Task switching: a PDP model

When subjects switch between a pair of stimulus-response tasks, reaction time is slower on trial N if a different task was performed on trial N - 1. We present a parallel distributed processing (PDP) model that simulates this effect when subjects switch between word reading and color naming in response to Stroop stimuli. Reaction time on "switch trials" can be slowed by an extended response selection process which results from (a) persisting, inappropriate states of activation and inhibition of task-controlling representations; and (b) associative learning, which allows stimuli to evoke tasks sets with which they have recently been associated (as proposed by Allport & Wylie, 2000). The model provides a good fit to a large body of empirical data, including findings which have been seen as problematic for this explanation of switch costs, and shows similar behavior when the parameters are set to random values, supporting Allport and Wylie's proposal.     

Word recognition in a phonemic dyslexic patient

The systems underlying word recognition were investigated in a single case study of a patient (K.F.) with an acquired dyslexia. His reading performance was related to parts of speech, word frequency and word concreteness, and his reading errors were analysed. There was a very striking difference between his ability to read concrete and abstract words. Furthermore visual errors, which could not be attributed to a deficit at a peripheral level, predominated; phonemic errors did not occur. It is argued that these findings support a dual encoding model of word recognition, the present case illustrating the impairment of the phonemic route, a direct graphemic-semantic route being relatively spared. These findings and interpretation are for the most part consistent with Marshall and Newcombe's (1973) studies of acquired dyslexia. The present findings are discussed in terms of more general theories of word recognition.     

Book reviews

SANDERS, A. F. (Ed.). Attention and Performance III. Amsterdam: North Holland Publishing Company. 1970. Pp. viii + 442. (Price not known.)

CORCORAN, D. W. J. Pattern Recognition. Harmondsworth: Penguin Books Ltd. 1971. Pp. 223. £0.50.

SCHRIER, A. M. and STOLLNITZ, F. (Eds.) Behaviour of Nonhuman Primates Vol. III. New York: Academic Press Inc. 1971. £4.45.

KINTSCH, W. Learning, Memory, and Conceptual Processes. New York: Wiley and Sons. 1970. Pp. 498. £4.40.

MORTON, J. (Ed.) Biological and Social Factors in Psycholinguistics. London: Logos Press. 1971. Pp. 215. £3.50.

RITCHIE RUSSELL, W. The Traumatic Amnesius. London: Oxford University Press. Pp. 84. £2.00.

MILLER, N. E. Selected Papers. Chicago: Aldine Publishing. 1971. Pp. 874. £15.00.

SUTHERLAND, N. S. AND MACKINTOSH, N. J. Mechanisms of Animal Discrimination Learning. New York: Academic Press. 1971. Pp. 559. $18.50.

FURCHTGOTT, E. (Ed.). Pharmacological and Biophysical Agents and Behavior. New York: Academic Press. 1971. Pp. xii+402. $14.50.

EYSENCK, H. J., ARNOLD, W. AND MEILI,R. (Eds). Encyclopedia of Psychology. Volume I. London: Search Press. 1972. Pp. 396. £8.00.     

Psychology and social control

The history of social control applications of psychology and the likelihood of a future increase in their importance are assessed. The effects of military funding of psychological research and the social consequences of very widespread unemployment are specifically considered. It is argued that psychology and related areas of cognitive science and neuroscience may well become increasingly relevant in the development of the technical components of such techniques rather than in providing ideological justifications for their use.     

Lesioning an attractor network: investigations of acquired dyslexia

A recurrent connectionist network was trained to output semantic feature vectors when presented with letter strings. When damaged, the network exhibited characteristics that resembled several of the phenomena found in deep dyslexia and semantic-access dyslexia. Damaged networks sometimes settled to the semantic vectors for semantically similar but visually dissimilar words. With severe damage, a forced-choice decision between categories was possible even when the choice of the particular semantic vector within the category was not possible. The damaged networks typically exhibited many mixed visual and semantic errors in which the output corresponded to a word that was both visually and semantically similar. Surprisingly, damage near the output sometimes caused pure visual errors. Indeed, the characteristic error pattern of deep dyslexia occurred with damage to virtually any part of the network.     

Introspective physicalism as an approach to the science of consciousness

Most 'theories of consciousness' are based on vague speculations about the properties of conscious experience. We aim to provide a more solid basis for a science of consciousness. We argue that a theory of consciousness should provide an account of the very processes that allow us to acquire and use information about our own mental states - the processes underlying introspection. This can be achieved through the construction of information-processing models that can account for 'Type-C' processes. Type-C processes can be specified experimentally by identifying paradigms in which awareness of the stimulus is necessary for an intentional action. The Shallice (1988b) framework is put forward as providing an initial account of Type-C processes, which can relate perceptual consciousness to consciously performed actions. Further, we suggest that this framework may be refined through the investigation of the functions of prefrontal cortex. The formulation of our approach requires us to consider fundamental conceptual and methodological issues associated with consciousness. The most significant of these issues concerns the scientific use of introspective evidence. We outline and justify a conservative methodological approach to the use of introspective evidence, with attention to the difficulties historically associated with its use in psychology.