Tim Shallice

Attention to Action

Much effort has been made to understand the role of attention in perception; much less effort has been placed on the role attention plays in the control of action. Our goal in this chapter is to account for the role of attention in action, both when performance is automatic and when it is under deliberate conscious control. We propose a theoretical framework structured around the notion of a set of active schemas, organized according to the particular action sequences of which they are a part, awaiting the appropriate set of conditions so that they can become selected to control action. The analysis is therefore centered around actions, primarily external actions, but the same principles apply to internal actions—actions that involve only the cognitive processing mechanisms. One major emphasis in the study of attentional processes is the distinction between controlled and automatic processing of perceptual inputs (e.g., Shiffrin & Schneider, 1977). Our work here can be seen as complementary to the distinction between controlled and automatic processes: we examine action rather than perception; we emphasize the situations in which deliberate, conscious control of activity is desired rather than those that are automatic.

Deep dyslexia: A case study of connectionist neuropsychology

Abstract Deep dyslexia is an acquired reading disorder marked by the Occurrence of semantic errors (e.g. reading RIVER as “ocean”). In addition, patients exhibit a number of other symptoms, including visual and morphological effects in their errors, a part-of-speech effect, and an advantage for concrete over abstract words. Deep dyslexia poses a distinct challenge for cognitive neuropsychology because there is little understanding of why such a variety of symptoms should co-occur in virtually all known patients. Hinton and Shallice (1991) replicated the co-occurrence of visual and semantic errors by lesioning a recurrent connectionist network trained to map from orthography to semantics. Although the success of their simulations is encouraging. there is little understanding of what underlying principles are responsible for them. In this paper we evaluate and, where possible, improve on the most important design decisions made by Hinton and Shallice, relating to the task, the network architecture, the trai...

Response suppression, initiation and strategy use following frontal lobe lesions.

Ninety-one patients with cerebral lesions were tested on a task involving two conditions. In the first condition (response initiation) subjects were read a sentence from which the last word was omitted and were required to give a word which completed the sentence reasonably. In the second condition (response suppression) subjects were asked to produce a word unrelated to the sentence. Patients with frontal lobe involvement showed longer response latencies in the first condition and produced more words which were related to the sentence in the second, in comparison to patients with lesions elsewhere. Moreover, in the second condition patients with frontal lobe lesions produced fewer words which showed the use of a strategy during response preparation. Performance on the initiation and suppression conditions was unrelated at the group or single case level. The relationship between response initiation, suppression and strategy use are discussed.

The involvement of the frontal lobes in cognitive estimation.

Ninety-six patients with localised cerebral lesions were tested on a task of providing reasonable answers to Cognitive Estimate questions. These questions are ones that can be answered using general knowledge available to almost all subjects, but for which no immediately obvious strategy is available. It was found that patients with frontal lesions gave significantly more bizarre answers than patients with more posterior lesions. This effect is interpreted in terms of Lurias (1966) theory of the planning functions of the frontal lobes.

Neuropsychological impairments of short-term memory

List of contributors Acknowledgements General introduction Part I. The Functional Architecture of Auditory-Verbal (Phonological) Short-Term Memory and its Neural Correlates: 1. The impairment of auditory-verbal short-term storage Tim Shallice and Giuseppe Vallar 2. The development of the concept of working memory: implications and contributions of neuropsychology Alan D. Baddeley 3. Multiple phonological representations and verbal short-term memory Frances J. Friedrich 4. Electrophysiological measures of short-term memory Arnold Starr, Geoffrey Barrett, Hillel Pratt, Henry J. Michalewski and Julie V. Patterson Part II. Phonological Short-Term Memory and Other Levels of Information Processing: Studies in Brain-Damaged Patients with Defective Phonological Memory: 5. Auditory and lexical information sources in immediate recall: evidence from a patient with deficit to the phonological short-term store Rita Sloan Berndt and Charlotte C. Mitchum 6. Neuropsychological evidence for lexical involvement in short-term memory Eleanor M. Saffran and Nadine Martin 7. Auditory-verbal span of apprehension: a phenomenon in search of a function? Rosaleen A. McCarthy and Elizabeth K. Warrington 8. Short-term retention without short-term memory Brian Butterworth, Tim Shallice and Frances L. Watson Part III. Short-Term Memory Studies in Different Populations (Children, Elderly, Amnesics) and of Different Short-Term Memory Systems: 9. Developmental fractionation of working memory Graham J. Hitch 10. Adult age differences in working memory Fergus I. M. Craik, Robin G. Morris and Mary L. Gick 11. Lipreading, neuropsychology and immediate memory Ruth Campbell 12. Memory without rehearsal David Howard and Sue Franklin 13. The extended present: evidence from time estimation by amnesics and normals Marcel Kinsbourne and Robert E. Hicks Part IV. Phonological Short-Term Memory and Sentence Comprehension: 14. Short-term memory and language comprehension: a critical review of the neuropsychological literature David Caplan and Gloria S. Waters 15. Neuropsychological evidence on the role of short-term memory in sentence processing Randi C. Martin 16. Short-term memory impairment and sentence processing: a case study Eleanor M. Saffran and Nadine Martin 17. Phonological processing and sentence comprehension: a neuropsychological case study Giuseppe Vallar, Anna Basso and Gabriela Bottini 18. Working memory and comprehension of spoken sentences: investigation of children with reading disorder Stephen Crain, Donald Shankweiler, Paul Macaruso and Eva Bar-Shalom Name index Subject index.

Independent functioning of verbal memory stores: A neuropsychological study

Five experiments are described concerning verbal short-term memory performance of a patient who has a very markedly reduced verbal span. The results of the first three, free recall, the Peterson procedure and an investigation of proactive interference, indicate that he has a greatly reduced short-term memory capacity, while the last two, probe recognition and missing scan, show that this cannot be attributed to a retrieval failure. Since his performance on long-term memory tasks is normal, it is difficult to explain these results with theories of normal functioning in which verbal STM and LTM use the same structures in different ways. They also make the serial model of the relation between STM and LTM less plausible and support a model in which verbal STM and LTM have parallel inputs.

Frontal lesions and sustained attention

Neurological patients were presented with a succession of 2-11 stimuli which they were required to count, reporting the number in the series when it finished. The stimuli were binaural clicks, or pulses on the right or on the left index finger. Regardless of stimulus modality or lateralization, patients with lesions involving the right frontal lobe were impaired when the presentation rate was 1/sec. There was no corresponding impairment when the presentation rate was increased to 7/sec. It is argued that at slow rates when the task was monotonous patients with right-frontal lesions were less able than others to sustain attention voluntarily.

CONTENTION SCHEDULING AND THE CONTROL OF ROUTINE ACTIVITIES

The control of routine action is a complex process subject both to minor lapses in normals and to more severe breakdown following certain forms of neurological damage. A number of recent empirical studies (e.g. Humphreys & Ford, 1998; Schwartz et al., 1991, 1995, 1998) have examined the details of breakdown in certain classes of patient, and attempted to relate the findings to existing psychological theory. This paper complements those studies by presenting a computational model of the selection of routine actions based on competitive activation within a hierarchically organised network of action schemas (cf. Norman & Shallice, 1980, 1986). Simulations are reported which demonstrate that the model is capable of organised sequential action selection in a complex naturalistic domain. It is further demonstrated that, after lesioning, the model exhibits behaviour qualitatively equivalent to that observed by Schwartz et al., in their action disorganisation syndrome patients.

Confidence in Recognition Memory for Words: Dissociating Right Prefrontal Roles in Episodic Retrieval

We used event-related functional magnetic resonance imaging (efMRI) to investigate brain regions showing differential responses as a function of confidence in an episodic word recognition task. Twelve healthy volunteers indicated whether their old-new judgments were made with high or low confidence. Hemodynamic responses associated with each judgment were modeled with an early and a late response function. As predicted by the monitoring hypothesis generated from a previous recognition study [Henson, R. N. A., Rugg, M. D., Shallice, T., Josephs, O., & Dolan, R. J. (1999a). Recollection and familiarity in recognition memory: An event-related fMRI study. Journal of Neuroscience, 19, 3962-3972], a right dorsolateral prefrontal region showed a greater response to correct low-versus correct high-confidence judgements. Several regions, including the precuneus, posterior cingulate, and left lateral parietal cortex, showed greater responses to correct old than correct new judgements. The anterior left and right prefrontal regions also showed an old-new difference, but for these regions the difference emerged relatively later in time. These results further support the proposal that different subregions of the prefrontal cortex subserve different functions during episodic retrieval. These functions are discussed in relation to a monitoring process, which operates when familiarity levels are close to response criterion and is associated with nonconfident judgements, and a recollective process, which is associated with the confident recognition of old words.

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 Newcombes (1973) studies of acquired dyslexia. The present findings are discussed in terms of more general theories of word recognition.