Preserved Vocabulary and Reading Acquisition in an Amnesic Child
Charles, A. Ahern, Frank B. Wood, Christine M. McBrien Section of Neuropsychology Bowman Gray School of Medicine Medical Center Blvd. Winston-Salem, NC 27157 Telephone: 415-206-5270 Fax: 415-206-4722 E-Mail: ChuckA2651@aol.com
This chapter presents the case of a nine year old boy who is amnesic as a result of congenital brain damage. Despite severe memory impairment for the events that constitute his experience, reading and vocabulary acquisition are shown to be within normal limits at age 9. This is interpreted as evidence of a dissociation between semantic and episodic memory systems. Observational data supporting this conclusion are also presented. The wider theoretical implications of this view are discussed. Methodologically, this study suggests there is value in attending to psychological variables in studies which aim to measure cognitive capabilities of brain-injured individuals.
This chapter will present findings concerning a remarkable nine year old boy, T.J., who is amnesic due to congenital brain damage. Specifically, we will focus on the implications of areas of preserved memory performance for a rather long-standing disagreement in the literature concerning theories which seek to describe the separate systems which constitute human memory.
While memory impairment in amnesia is diffuse, it is not global. Thirty years ago, Milner ( 1966) and Corkin ( 1968) focused renewed attention on the fact that some memory functions appear to be preserved in human amnesia. Case studies of two patients in particular, H.M. and N.A., demonstrated that amnesia involves selective memory impairment. These data converged with data from animal studies which indicated that the memory deficits which resulted from specific lesions were circumscribed and definable ( Pribram 1966, 1969).
These works engendered intensified interest in the nature of amnesia that has continued to the present day. When understood as a selective impairment, the nature of amnesia becomes subtle and fascinating. Since the Milner and Corkin studies, hundreds of papers have explored empirically which memory functions are spared in amnesia. The findings have served as the basis for theoretical accounts of distinct memory systems in amnesia. These accounts have also been considered relevant to understanding the structure of normal memory; that is, to identifying and defining distinct systems operating in normal memory ( Schacter, 1987).
Evidence for a distinct memory system usually features claims that the system can be behaviorally dissociated from other memory systems. Dissociation is demonstrated when performance on memory tasks assumed to represent one system is shown to be at a different level than performance on tasks