that we should think again about the particularity of schizophrenia and think more about a general psychotic dimension (are you listening Professor Eysenck?). In spite of the pessimism, this reviewer found it a fascinating book and full of ideas for future work.

Peter H. Venables University, of York

H. POIZNER, E.S. KLIMA and U. BELLUGI, What the Hands Reveal about the Brain (A Bradford Book - MIT Press, London and Cambridge, MA, 1987)

pp. xvii + 236, E22.50.

In recent years, research on sign languages has challenged our preconcep- tions about the structure of human language. From earlier views of the deaf as having no language, a body of knowledge about different sign languages has developed in psychology and linguistics, including such topics as memory for and processing of signs, the sub-lexical structure and grammar of sign lan- guages, and sign language acquisition (Klima & Bellugi 1979, Kyle & Woll, 1985). Sign languages must now be accepted as complex linguistic systems, with communities of users, sharing universal properties with spoken languages, but occurring in the visual-spatial modality, and using, amongst other struc- tures, spatial relationships for syntactic purposes.

In What the Hands Reveal about the Brain, Poizner et al. extend the challenge of sign language research to neuro-psychology and neuro-linguistics. Over a number of years they have conducted research in the field of hemi- sphere lateralisation and deaf aphasia, and this book presents an overview of this work, some of which has previously been published.

Sign language neuro-psychology is of crucial importance precisely because sign languages occur in the visual-spatial modality. As John Marshall’s concise introduction points out, brain damage in signers presents a paradox: The left hemisphere is the material substrate for language in the vast majority of right-handed people; the right hemisphere appears to play a leading role with respect to visual-spatial abilities. Which hemisphere therefore takes precedence when the communication system simultaneously qualifies as both a language and as a precise set of gestures executed in space and perceived visually?

Chapter 1 is a summary of Klima and Bellugi (1979). It provides the basis for the analysis of the aphasias described later in the book. As research on American Sign Language (ASL) has moved on since 1979, some of the analysis presented is out of date; this has implications for the aphasia descriptions, as will be noted later in this review.

Book reoiews 281

Chapter 2 reviews the brief literature on sign aphasics. The rarity of congenital deafness (1 per 2000 births), and the lack of understanding of sign languages, has meant that there have been only 14 cases reported since 1896. A comprehensive description then follows of the test battery used by Poizner and his colleagues. This should be of great practical interest to clinical psychologists, speech therapists and others who might encounter deaf aphasic patients. The tests administered by the group fall into four categories; (1) the Boston Diagnostic Aphasia Examination, adapted for deaf patients, (2) a

series directed towards production and comprehension of ASL grammatical structures, (3) tests of the patients’ capacity for representational and non-rep- resentational movements of hands and arms, (4) a series of non-language visuo-spatial tests for differentiating left and right hemisphere damage. It should be noted that for use outside the U.S.A.. all these tests would need to be further adapted to the specific sign language used by a deaf subject under investigation. At the end of the chapter the six deaf patients studied are introduced, together with personal and demographic data, and results of CT scans.

Chapters 3 and 4 present data from the three left-lesioned subjects; chapter 5 presents data from the three right-lesioned subjects. There is a somewhat irritating tendency throughout to keep repeating summary findings at the end of every section and chapter, presumably to hammer home the theme of sign language aphasia and its similarity to spoken language aphasia.

For the three (left-lesioned) signers exhibiting various aphasias. the sign language error analysis is of particular importance. A problem arises for the researcher presenting sign language data. In the absence of a writing system for ASL, there are four ways to present data; to use a narrative description, to present drawings or photographs, to use one of the transcription systems designed by linguists for sign language analysis, or to use English glosses of utterances. The authors have sought to give a balance in these sections, using whichever presentation they feel most appropriate for a given example. The reader may feel that in some cases it might be helpful to know more about the actual errors: “as the stimuli became larger and more complex. she would transpose signs and omit or add signs that had not been in the original stimulus” (p. 86).

The linguistic analysis of the errors also raises questions. For example. a Wernicke-type aphasic is described as producing semantically bizarre signs (EARTH for ROOM, BED for CHAIR, etc.), using semantically related items from the same lexical category. This subject also produced ‘classifier’ errors (p. 101) of the form CAR *PASS-BY-CL: /G/ instead of CAR PASS-BY-CL: /3/. In other words, the subject used the verb form appropriate for ‘a person walking’, in place of the correct ‘a vehicle driving’; a more elegant analysis would view this second group of errors as reflecting the same semantic selectional errors as the BED-CHAIR substitutions. The influence of

Klima & Bellugi’s analysis seems in this case to lead to pre-categorisation of the data, although at this stage in sign language grammatical analysis, psycho- linguistic and neuro-linguistic data should be used to assist linguistic descrip- tions.

In chapter 6, Poizner et al. seek to assess the relationship between apraxia and aphasia. The existence of sign language aphasics provides opportunities for testing the possible association between the two. Firstly, signing and gesture occur in the same visual-spatial modality ~ so dissociation of the two would suggest different underlying mechanisms. Secondly, because sign lan- guages use simultaneous as well as sequential movement structures for gram- matical purpose, aphasia in the absence of apraxia would provide evidence against the hypothesis that both aphasia and apraxia result from inability to program complex movements. Finally, because the articulators involved in sign language production are clearly visible, we can compare errors in sign production with errors in production of non-language movements and ges- tures. Poizner et al.‘s findings suggest that sign language aphasia can occur independently of disorders of movement and gesture. These findings are supported by chapter 7 which explores visuo-spatial non-language capacity, and chapter 8, which discusses spatial mapping. The authors state that visuo-spatial processing outside ASL is identical with that of hearing speakers. There are some serious implications of this area of research for sign language linguists, however, as they find that the so-called spatial mapping of ASL differs in lateralisation (right-hemisphere) from spatialised syntax (left-hemi- sphere).

In summary, Poizner et al. present substantial evidence that language is a left-hemisphere activity, irrespective of language modality and in the absence of auditory input, and further, that similar classes of aphasias are found in signing patients as in speaking patients. They have made a comprehensive start on the their long-range objective: the study of the biological foundations of human language.

References

Klima, ES., & Bellugi, U. (1979). The signs of lunguuge. Cambridge MA: Harvard University

PIUS.

Kyle, J.G.. & Woll, B. (1985). Sign langmge: The study of deaf people und their language.

Cambridge: Cambridge University Press.

Bencie Wall University of Bristol