The word order problem in agrammatism : I. Comprehension

The results of a picture-pointing comprehension test show that agrammatic aphasics have difficulty understanding sentences in which the underlying semantic roles are marked by the order of noun phrases around a verbal element. Agrammatic patients performed poorly on reversible constructions involving spatial prepositions (e.g., “The square is above the circle”) and verbs (e.g., “The dancer applauds the clown”). These results have significance for the interpretation of the underlying disturbance in agrammatism—whether the deficit is syntactic or purely phonological.     

Experimental evidence for a minimalist account of English resumptive pronouns.

In this article we provide evidence for a Minimalist account of English-type resumptive pronouns. Our findings provide empirical support for syntactic theories that, like Minimalist accounts, allow for competition among derivations. According to our account, resumptive pronouns are spell-outs of traces. For reasons of economy, the resumptive pronoun surfaces only when the derivation with the trace is precluded by syntactic principles. This account predicts that resumptive pronouns should only improve violations of constraints on representation, and not violations of constraints on movement. We tested this prediction by conducting an acceptability judgment task with 36 native speakers of English. The results bore out our prediction; subjects preferred the resumptive pronoun over the trace in cases where the trace itself was illicit, but not in cases where only the movement operation was illicit.     

Aphasics' selective deficits in appreciating grammatical agreements

This study attempted to dissociate in aphasic patients different aspects of grammatical capacity. Subjects were asked to evaluate sentences containing violations of agreements between pronouns and verbs. Agreements which are considered primarily structural in nature were violated (e.g., a surface object case like “them” placed in a surface subject sentential slot) while other violated agreements seemed to involve both structural and semantic information (e.g., lack of agreement between a pronoun and a verb in terms of the number of people performing the act). These violations were couched in one of three types of sentential frames which varied in terms of syntactic complexity (e.g., active declarative vs. passive syntactic voices). The results revealed that Broca's aphasics found agreement violations difficult to detect in complex syntactic frames. They were quite successful at detecting even violations of the largely structural “case” type of agreement, however, when couched in simpler syntactic frames. Fluent aphasics encountered more difficulty detecting violations of agreements involving both semantic and structural information than agreements which were primarily structural in nature, that is, regardless of the syntactic frame. These unique performance profiles suggest that Broca's aphasics may be agrammatic only with respect to certain aspects of a sentence's structure, and that fluent aphasics may also experience some selective—but different—grammatical deficits.     

Repetition in the transcortical aphasias

Transcortical aphasic patients were assessed on a repetition task comprised of both well-formed and deviant sentences. The patients faithfully repeated those sentences that were factually incorrect but grammatically well formed, and those sentences that were ungrammatical because of selection restriction violations. In contrast, presented with sentences featuring only minor syntactic violations (e.g., lack of number agreement), the patients spontaneously, and without awareness, resisted exact repetition; moreover, the resultant changes most often served to correct the syntactic deviations. Repetitions of sentences of this latter type also revealed a difference between the patients as a function of level of comprehension. The transcortical motor aphasic patient was influenced by semantic factors in his alterations of the minor syntactic violations, while the transcortical sensory aphasic was not. These findings are discussed in relation to the notion of autonomous syntactic processing. They are taken to suggest that syntactic facts such as number agreement are represented at a level in the processing chain that is distinct from that of semantic representation.     

Production of non-canonical sentences in agrammatic aphasia: limits in representation or rule application?

The study reported here compares two linguistically informed hypotheses on agrammatic sentence production, the TPH [Friedmann, N., & Grodzinsky, Y. (1997). Tense and agreement in agrammatic production: Pruning the syntactic tree. Brain and Language, 56, 397-425.] and the DOP [Bastiaanse, R., & van Zonneveld, R. (2005). Sentence production with verbs of alternating transitivity in agrammatic Broca's aphasia. Journal of Neurolinguistics, 18, 59-66]. To explain impaired production of non-canonical sentences in agrammatism, the TPH basically relies on deleted or pruned clause structure positions in the left periphery, whereas the DOP appeals to limitations in the application of movement rules. Certain non-canonical sentences such as object-questions and object-relative clauses require the availability of nodes in the left periphery as well as movement to these nodes. In languages with relatively fixed word order such as English, the relevant test cases generally involve a coincidence of left periphery and movement, such that the predictions of the TPH and the DOP are identical although for different reasons. In languages with relatively free word order such as German, on the other hand, it is possible to devise specific tests of the different predictions due to the availability of scrambling. Scrambled object sentences, for example, do not involve the left periphery but do require application of movement in a domain below the left periphery. A study was conducted with German agrammatic subjects which elicited canonical sentences without object movement and non-canonical scrambled sentences with object movement. The results show that agrammatic speakers have a particular problem with the production of scrambled sentences. Further evidence reported in the study from spontaneous speech, elicitation of object relatives, questions and passives and with different agrammatic subjects confirms that non-canonical sentences are generally harder to produce for agrammatics. These findings provide evidence in favor of the DOP and it will be argued that a cross-modal explanation of agrammatic deficits is possible if two factors--movement and canonicity--are taken into consideration.     

Sensitivity to inflectional morphology in agrammatism: investigation of a highly inflected language

We present the results of a study with six Serbo-Croatian-speaking agrammatic patients on a test of inflectional morphology in which subjects judged whether spoken sentences were grammatical or ungrammatical. Sensitivity to two kinds of syntactic features was investigated in these aphasic patients: (1) subcategorization rules for transitive verbs (which must be followed by a noun in the accusative case; intransitive verbs can be followed by nouns in other noun cases); (2) sensitivity to the inflectional morphology marking noun case. The test items consisted of three-word sentences (noun-verb-noun) in which verb transitivity and appropriateness of the case inflection of the following noun were manipulated. Results of the grammaticality judgment task show that both syntactic properties are preserved in these patients.     

Processing "d-linked" phrases

Linguists draw a distinction between two types of interrogatives: discourse linked (d-linked) phrases such as which man, which implies the existence of a set of contextually determined entities (men) from which the speaker is asking for a choice, and non–d-linked interrogatives such as who, which carry no such implication. Two questionnaires and an on-line reading study showed that readers prefer a d-linked phrase more than a non–d-linked phrase as the antecedent for a pronoun, suggesting that d-linked phrases are immediately instantiated in a discourse representation that is checked during the process of pronoun interpretation. Comparable difficulty is not observed for non–d-linked interrogatives. A questionnaire and an on-line listening study also showed that readers and listeners were more willing to accept a grammatical island violation containing a pronoun when the pronoun's antecendent was a d-linked interrogative than when the antecedent was non–d-linked, suggesting that they check a discourse representation for the pronoun antecedent. All results suggest that d-linked phrases are immediately interpreted in a discourse representation, not just in a syntactic representation.     

Learning to divide the labor: an account of deficits in light and heavy verb production

Theories of sentence production that involve a convergence of activation from conceptual‐semantic and syntactic‐sequential units inspired a connectionist model that was trained to produce simple sentences. The model used a learning algorithm that resulted in a sharing of responsibility (or “division of labor”) between syntactic and semantic inputs for lexical activation according to their predictive power. Semantically rich, or “heavy”, verbs in the model came to rely on semantic cues more than on syntactic cues, whereas semantically impoverished, or “light”, verbs relied more on syntactic cues. When the syntactic and semantic inputs were lesioned, the model exhibited patterns of production characteristic of agrammatic and anomic aphasic patients, respectively. Anomic models tended to lose the ability to retrieve heavy verbs, whereas agrammatic models were more impaired in retrieving light verbs. These results obtained in both sentence production and single‐word naming simulations. Moreover, simulated agrammatic lexical retrieval was more impaired overall in sentences than in single‐word tasks, in agreement with the literature. The results provide a demonstration of the division‐of‐labor principle, as well as general support for the claim that connectionist learning principles can contribute to the understanding of non‐transparent neuropsychological dissociations.     

A note on the "word-order problem" in agrammatism

This brief note has two parts. First, it presents an analysis of the ability of English agrammatic patients to assign the thematic roles of agent, instrument, theme, and locative to noun phrases in active and passive sentences and prepositional phrases. Data regarding this ability have been presented by Schwartz, Saffran, and Marin (Brain and Language, 10, 149-262 (1980) regarding comprehension, and by Saffran, Schwartz, and Marin (Brain and Language, 10, 263-280 (1980) regarding production. These authors claim their data show that English agrammatic aphasics do not map "word order" onto thematic information. However, a very simple set of principles accounts for all their results, including results which are discrepant in their treatment, but requires that English agrammatics assign thematic roles to NPs in part by virtue of the position of an NP in a sentence or a phrase. In the second part of this note, several issues raised by this re-analysis are briefly discussed.     

Situation models,propositions, and the fan effect

According to theories of language comprehension, people can construct multiple levels of representation: the surface form, the propositional text base, and the situation model. In this study, I looked at how the referential nature of memory probes affects the experience of retrieval interference. All the subjects memorized sentences about objects in locations (e.g., “The potted palm is in the hotel”). When memory probes were sentences and, therefore, referential and most closely associated with the situation model level, no interference was observed during retrieval for information that could be integrated into a common situation model. In contrast, interference was observed in such cases when the memory probes were concept pairs (POTTED PALM-HOTEL) and hence not directly referential. This is interpreted to mean that nonreferential memory probes involve surface form and text base representations more than do referential sentence probes.     

Syntactic and semantic contributions to sentence comprehension in agrammatism

Five aphasic subjects, who demonstrated agrammatic speech, and eight control subjects were presented with a sentence-picture matching task in which the factors of syntactic complexity, semantic reversibility, and sentence plausibility were independently varied. A subset of the sentences was patterned after that presented by A. Caramazza and E. Zurif (1976, Brain and Language, 5, 572-583) who concluded that Broca's aphasics rely on semantic constraints instead of syntactic information for sentence comprehension. Our aphasic subjects showed the same pattern of performance on this subset of sentences. However, the results from the full set of sentence materials we tested show that the aphasic subjects could perform some sentence level syntactic analyses, even when syntactic information conflicted with semantic constraints. The aphasic subjects correctly interpreted most active and passive sentences. They failed, however, to assign thematic roles and adjectives in center-embedded relative sentences, and instead relied on nonsyntactic information. These results show that both semantic and syntactic information contributed to sentence comprehension in the aphasic subjects we tested, in contrast to previous claims that syntactic and semantic processes are completely dissociated in this population.     

Semantic heuristics,syntactic analysis,and case-role assignment

Forster's (1979) proposals regarding the autonomy of syntax and his explanation of experiments that support the alternative interactive theory of syntactic analysis are briefly reviewed. It is argued that a slightly different account is consistent with evidence from neuropsychology. On the basis of the work of Linebarger, Schwartz, and Saffran (1983) with agrammatics, a distinction is drawn between a sentence's syntactic representation and its propositional representation. The suggestion is that the processor responsible for assigning case roles within a proposition has access to semantic and pragmatic information as well as to a purely syntatic representation. In this way, certain top-down effects in sentence processing can be comfortably accommodated without violating the autonomy of the syntactic representation.     

The isomorphic mapping hypothesis: evidence from Korean

This paper evaluates the relative merits of the trace deletion hypothesis, which attributes agrammatic comprehension difficulties to the loss of traces, and the isomorphic mapping hypothesis, which proposes that agrammatics have difficulty understanding sentences in which there is a nonisomorphic mapping between the syntactic representation and the corresponding event in the real world. (The two are isomorphic if the order of NPs reflects the place of entities in the event's 'action chain.' Since agents act on themes and transmit them to goals, the agent-theme-goal order is isomorphic with the corresponding event but the agent-goal-theme order is not.) The two hypotheses contrast in the predictions they make concerning goal-theme and theme-goal patterns in Korean: the TDH predicts degraded performance on the theme-goal structure (which is derived from the goal-theme structure); the IMH predicts difficulties on the goal theme structure, since it is nonisomorphic. Results of a comprehension study involving four Korean Broca's aphasics provide strong support for the IMH over the TDH.     

Verb deficits in Alzheimer's disease and agrammatism: implications for lexical organization

This study examined the nature of verb deficits in 14 individuals with probable Alzheimer's Disease (PrAD) and nine with agrammatic aphasia. Production was tested, controlling both semantic and syntactic features of verbs, using noun and verb naming, sentence completion, and narrative tasks. Noun and verb comprehension and a grammaticality judgment task also were administered. Results showed that while both PrAD and agrammatic subjects showed impaired verb naming, the syntactic features of verbs (i.e., argument structure) influenced agrammatic, but not Alzheimer's disease patients' verb production ability. That is, agrammatic patients showed progressively greater difficulty with verbs associated with more arguments, as has been shown in previous studies (e.g., Kim & Thompson, 2000; Thompson, 2003; Thompson, Lange, Schneider, & Shapiro, 1997), and suggest a syntactic basis for verb production deficits in agrammatism. Conversely, the semantic complexity of verbs affected PrAD, but not agrammatic, patients' performance, suggesting "bottom-up" breakdown in their verb lexicon, paralleling that of nouns, resulting from the degradation or loss of semantic features of verbs.     

Real-time comprehension processes in agrammatism: A case study

The ability of an agrammatic patient to construct structural syntactic and interpretative representations on-line was tested in two experiments. The first focused on global representations spanning an entire utterance, while the second examined lexical syntactic and semantic constraints on verb-argument relations. An off-line version of the second experiment was also carried out. There were two major findings. First, the patient could construct a semantic, but not syntactic, representation of an utterance. Second, he was much more dependent than normal upon pragmatic information. These results are discussed with respect to current claims about the nature of agrammatic comprehension deficits.     

Sensitivity to Syntactic Changes in Garden Path Sentences

The results of two text-change experiments are reported. The experiments were designed to investigate the syntactic representation of garden path sentences such as While the man hunted the deer that was brown and graceful ran into the woods, specifically the claim that a significant number of misinterpretations of such sentences are due to incomplete syntactic reanalysis (Christianson et al. Cogn Psychol 42:368–407, 2001). In the experiments reported here, the pronoun it was added (Expt. 1) or deleted (Expt. 2) from short texts containing such sentences. Participants were more or less likely to notice both deletions and additions of it in certain syntactic contexts, as predicted by the incomplete reanalysis account. Correlations with reading times support this interpretation of the results. Overall, the data are consistent with a “good enough” view of language processing (Ferreira et al. J Psycholinguist Res 30:3–20, 2001).     

Working memory and planning during sentence production

Speakers retrieve conceptual, syntactic and lexical information in advance of articulation during sentence production. What type of working memory (WM) store is used to hold the planned information before speaking? To address this question, we measured onset latencies when subjects produced sentences that began with either a complex or a simple initial noun phrase, while holding semantic, phonological or spatial information in WM. Although we found that subjects had longer onset latencies for sentences beginning with a complex noun phrase, showing a phrasal scope of planning, the magnitude of this complexity effect was not affected by any type of WM load. However, subjects made more syntactic errors (but not lexical errors) for sentences beginning with a complex noun phrase, suggesting that advance planning for these phrases occurs at a syntactic rather than lexical–semantic level, which may account for the lack of effect with various types of WM load in the current study.