functions and knowledge of the serial order of actions in a sequence. With regard to the production system it is important to examine various dimensions of performance in order to acquire a view of the extent of the deficits in limb praxis. Further, careful analyses of the types of errors observed as well as the conditions under which they occur is essential to an understanding of the nature of the underlying disorder. With regard to sequences of actions Roy ( 1981) and others (e.g., Kimura, 1977, 1982) have provided such a description. For single gestures we have begun to examine such error patterns under various performance conditions (e.g., to verbal command, to imitation). Other implications of this approach to the study of apraxia have been discussed by Roy ( 1983) and include the nature of the motor task (e.g., complexity), the dependent measures employed to assess performance (e.g., accuracy vs timing performance), and the role of context in facilitating performance in the apraxic patient.
Preparation of this manuscript was supported through grants from NSERC and NHRDP.
Basso A., Luzzatti C., & Spinnler H. ( 1980). "Is ideomotor apraxia the outcome of damage to well-defined regions of the left hemisphere?" Journal of Neurology, Neurosurgery and Psychiatry, 43, 118-126.
Brown J. W. ( 1972). Aphasia, apraxia & agnosia: Clinical and theoretical aspects. Springfield, IL: CC Thomas.
DeAjuriaguerra J., & Tissot R. ( 1969). "The apraxias". In P. J. Vinken & G. W. Bruyn (Eds.), Handbook of clinical neurology, Volume 4, Disorders of speech, perception and symbolic behavior. Amsterdam: North-Holland.
Goodglass H., & Baker E. ( 1976). "Semantic field, naming and auditory comprehension in aphasia". Brain Language, 3, 359-374.
Heilman K. M. ( 1979). "Apraxia". In K. M. Heilman & E. Valenstein (Eds.), Clinical neuropsychology. New York: Oxford University Press.
Heilman K. M., Rothi L. J., & Valenstein E. ( 1982). "Two forms of ideomotor apraxia". Neurology, 32, 342-346.
Keele S. ( 1980). "Behavioural analysis of motor control". In V. Brooks (Ed.), Handbook of physiology, motor control. Washington, D.C.: American Physiology Society.
Kimura D. ( 1977). "Acquisition of a motor skill after left hemisphere damage". Brain, 100, 527-542.