Syntactic features in reanalysis: Positive and negative symptoms

Meng and Bader have presented evidence that a Case conflict is a more effec tive cue for garden-path reanalysis than a number conflict is, for German,v h-sentences with subject-object ambiguities. The preferred first-pass analy sis has the wh-trace in subject position, although object position is corre ct. In a speeded grammaticality judgment task, perceivers accepted Case-dis ambiguated examples more often and more rapidly than number-disambiguated e xamples, although comprehension questions indicated that both were eventual ly understood correctly. For ungrammatical sentences, a Case mismatch error resulted in more false positive grammaticality judgments than a number mis match error. We offer an explanation for why Case and number features diffe r in these two ways in their effects on sentence processing. We propose, wi thin the Diagnosis Model of garden-path processing, that reanalysis trigger ed by a Case mismatch guides the parser more effectively toward the correct structure. Case is a positive symptom, which carries information about the new structure that must be built. By contrast, a number mismatch is a nega tive symptom it invalidates the incorrect structure without showing how to rebuild it, This difference in the transparency of garden-path repair can a lso account for the greater overacceptance of Case-disambiguated ungrammati cal sentences. The speeded grammaticality judgment task is designed to enco urage hasty responses. Usually, these are hasty rejections of garden path s entences that, on calmer reflection, the parser would find acceptable. Conv ersely, over-hasty acceptance could occur if some initial progress is made in resolving a grammatical problem. Thus, a higher rate of false positives on ungrammaticals is to be expected where reanalysis proceeds successfully for a while before blocking.