Sentence memory in aphasia.

A probe paradigm was used to assess memory for the surface structure of sentences in a group of anterior (Broca’s) and a group of posterior (Wernicke’s) aphasics. Three types of sentences were used: active, passive and center-embedded sentences. Results showed that for both patient groups memory for function words was especially impaired relative to the patient’s ability to recover content words. Further, both groups had marked difficulties in remembering center-embedded sentences. A second experiment rules out the possibility that this latter result was due to the extra syntactic complexity of the center-embedded sentences. Results from both experiments were interpreted as indicating that neither anterior nor posterior aphasics have normal surface structure memory representations and that the aphasic’s memory span for sentence material may be severely limited. RECENT work on the topic of sentence comprehension has emphasized the constructive nature of the process involved. That is, comprehension of a sentence requires the construction of an internal representation that encodes the meaning of individual lexical items as well as the syntactic and semantic relations among those items. This constructive process underlying sentence comprehension is believed to provide the basis for the representation of sentences in memory [I]. The representation that is initially constructed may undergo further abstraction and integration into more complex ideas consistent with contextual information and personal knowledge [2]. Even so, there is a brief period of time following the presentation of a sentence in which the subject has available a fairly veridical representation of that sentence -a representation from which detailed information about specific lexical items and about the exact syntactic form of the sentence can be retrieved [3, 41. However, whether or not this initial representation and subsequent constructions will be available depends upon the “depth of processing” the sentence receives at the time of input [5]. With these interrelated notions concerning initial sentence processing as a starting point, the present paper attempts to characterize the form of memory representations that are generated by anterior (Broca’s) and posterior (Wemicke’s) aphasics. In addition, it attempts to describe the type of syntactic and semantic processing performed by these patients in encoding sentences. *Please address reprint requests to Alfonso Caramaua, Department of Psychology, The Johns Hopkins University, Baltimore, Maryland 21218, U.S.A.