Psychological Bulletin1978, Vol. 85, No. 4, 898-918Semantic and Syntactic Processes in Aphasia:A Review of the LiteratureAlfonso Caramazza and Rita Sloan BerndtThe Johns Hopkins UniversityRecent investigations of lexical and syntactic aspects of language comprehensionin aphasia are reviewed. It is argued that these studies support theoretical as-sumptions concerning the functional independence of various components ofnormal language processing. Studies of the structure of the lexicon in aphasiaprovide support for componential theories of lexical semantics in that differenttypes of features of meaning can be selectively disrupted under conditions ofbrain damage. Studies of sentence comprehension support the existence of asyntactic mechanism that is independent of lexically based heuristic strategiesfor assigning meaning. There is evidence that these independent elements oflanguage are subserved by different portions of the dominant hemisphere of thebrain. Focal brain damage can thus cause selective disruption of components,allowing the separation of elements that are highly integrated in the normaladult. Studies of aphasic language, therefore, provide a valuable source of con-straints on theories of normal language processing.In a recent influential book, Fodor, Bever,and Garrett (1974) stated: "It is ... thesad truth that remarkably little has beenlearned about the psychology of languageprocesses in normals from over one hundredyears of aphasia study" (p. xiv). This viewmay not be far from the truth. Historically,the study of language dissolution has beenalmost exclusively the province of neurolo-gists, whose concerns were not so much withthe normal organization of language pro-cesses as with the correlation between brainstructures and specific language behaviors.Although traditional work in aphasia haslargely failed to provide direct informationDuring the writing of this review, Rita SloanBerndt was supported by Public Health ServiceTraining Grant 5 TCX MH 06742-18 to the JohnsHopkins University.The authors would like to thank Oscar Marin forhis comments on an earlier version of the article.They owe a special debt to Edgar Zurif, who al-lowed them to borrow freely many of the ideasthat they have developed in collaboration withhim over the past few years.Requests for reprints should be sent to AlfonsoCaramazza, Department of Psychology, The JohnsHopkins University, Baltimore, Maryland 21218.concerning the organization of normal lan-guage processes, it has established a solidfoundation from which more recent aphasio-logical research can address these questions.What is most important is that this earlywork has established that although no twoaphasics are exactly alike either in thenature of the disorder or in the consequentlanguage performance, it is the case thatthere are discernible patterns of dissolution.Focal brain damage to the dominant hemi-sphere (left hemisphere in most right-handedindividuals) does not simply result in anoverall undifferentiated reduction of languagecapacity or a random constellation of symp-toms (Geschwind, 1970, 1972; Luria, 1970).On the contrary, it appears that differentparts of the brain subserve different linguisticfunctions.For psychologists, however, of more im-portance than the brain/function correlationis the identification of different types ofaphasias characterized by predictable constel-lations of symptoms. The occurrence of suchwell-organized patterns of dissolution mayreflect natural divisions in the organization oflanguage processes in normal adults. ArmedCopyright 1978 by the American Psychological Association, Inc. 0033-2909/78/8504-0898$00.75898APHASIA899with this well-established fact that languagedissolution follows predictable patterns, re-cent investigators of aphasic language havebegun to ask questions that are of concernnot only to aphasiologists but also to psy-chologists concerned with normal languagefunctioning.There are two arguments that can be madeconcerning the importance of aphasia re-search to the study of normal processes. First,models of normal language functioningshould not be inconsistent with the dataobtained with aphasic populations. Since cur-rent theories of language are so underdeter-mined by data, it would be foolhardy toignore a source of constraint on permissibletheories of language. The second and moreimportant argument is based on the beliefthat there is ultimately more than a trivialconnection between psychological processesand the brain. This stronger claim is the onethat motivates this review. It is specificallyargued that in the ideal case, brain damageselectively impairs discrete components oflanguage, so processes that are highly inter-dependent in the normal adult can be moreclearly identified. Even in cases involvingcomplex patterns of dissolution, it is possibleby a judicious process of comparing variouspatient types to identify components of pro-cessing that are so closely intertwined in thenormal adult that they are irretrievable.Ultimately, research motivated on the basisof this claim should generate new hypothesesabout the structure of language processing.This review focuses on aphasia researchthat addresses two components that are in-volved in sentence comprehension: lexicaland syntactic processing. The basic issuesaddressed at the level of lexical processingconcern the question of the representation oflexical information. At the syntactic level,the concern is with determining whethersyntactic processes are independent of se-mantic and heuristic processes in sentencecomprehension.Comprehension in AphasiaResearch in aphasia has typically focusedon deficits in the productive capacities ofbrain-damaged patients, that is, on overtspeech behavior. Discussion of impairment ofthe ability to comprehend spoken languagehas been limited, for the most part, to im-pressions that a patient's comprehension isrelatively "impaired" or clinically "intact."Such global descriptions of the phenomenonof language comprehension obscure the factthat a highly complex interactive system ofcomponents and processes underlies the ex-traction of meaning from a particular config-uration of words. It is likely that damage todifferent parts of the brain will differentiallydisrupt these components of comprehension,just as the various elements of productivespeech are differentially affected.Several recent investigations have lookedmore carefully at the process of comprehen-sion in an attempt to disentangle the com-ponents