The role of the anterior left hemisphere in real-time sentence comprehension: evidence from split intransitivity

We investigate Broca's sentence comprehension as an impairment on normal syntactic composition: the slow-syntax hypothesis (SSH). Experiment 1 examines comprehension of object-relative clauses (Wh-movement). Experiment 2 examines comprehension of sentences with unaccusative verbs (NP-movement), which like passives, base-generate their theme-argument in object position. Guided by the SSH, both experiments test the prediction that syntax-dependent effects such as "gap-filling" are observable but in a delayed fashion. Results show that whereas no priming was obtained at the point of the trace, antecedent reactivation emerged 650 and 800 ms after the verb (for Wh- and NP-movement respectively). This shows, contrary to dependency-based generalizations, that Broca's patients are able to successfully implement dependencies, albeit in a protracted manner. Given the localization value provided by Broca's aphasia, this supports the notion that the temporal implementation of syntactic structure formation (i.e., the requirement that it be fast and automatic) depends on the integrity of the anterior left hemisphere.     

Role of referent concreteness in the acquisition of passive sentence comprehension through abstract modeling

The present experiment tested the hypothesis that development of syntactic comprehension through verbal modeling is enhanced by referent concreteness as a contextual influence. Young children heard a model narrate a series of events in passive form while the model either performed the corresponding activities, showed pictures portraying the same activities, or displayed no referential aids. In accord with prediction, verbal modeling with enactive referents produced higher levels of comprehension of passives than modeling with pictorial referents or modeling without referential aids. Modeling with pictorial referents and modeling without referents did not differ in overall efficacy. However, modeling alone produced results that were less consistent across different measures of comprehension. Children who lacked understanding of passives were more dependent on concrete referents than those who had some initial comprehension of the linguistic form. The results suggest that verbal modeling with pictorial referents and verbal modeling alone facilitate comprehension of passives, whereas verbal modeling with enactive referents promotes learning. Findings of a supplemental experiment reveal that the effects of verbal modeling on comprehension are enhanced when syntactic forms occur in a meaningful verbal context.     

Verb-based versus class-based accounts of actionality effects in children's comprehension of passives

Several studies have shown that children perform worse on tests of passive comprehension when the verb is non-actional than when it is actional. Most existing accounts focus on the semantic characteristics of the class of non-action verbs in explaining this difference. An alternative is a "verb-based" account in which passives are initially learned verb by verb, and children hear fewer non-actional passives in their language input. An analysis of the passives heard by Adam, Eve and Sarah (Brown, 1973) found more actional than non-actional passives, consistent with the verb-based account. In a second study, children tested for passive comprehension were re-tested a week later. The verb-based account predicts that children should show a consistent pattern of responses for individual verbs on test and re-test. Such consistency was found, with some inconsistency due to improvement over the re-test. Further analyses showed no effects of affectedness in explaining children's problems with passives. Finally, we discuss whether a mixed model containing both verb-based and class-based mechanisms is required to explain the actionality effects.     

Agrammatic Broca's aphasia is not associated with a single pattern of comprehension performance

One influential hypothesis posits that the brain regions implicated in Broca's aphasia are responsible for specific syntactic operations that are necessary for the comprehension and production of sentences (Grodzinsky, 1986, 1990, in press). The empirical basis of this hypothesis is the claim that Broca's aphasics have no difficulty understanding sentences in the active voice (and other "canonical" sentence types, such as subject relatives and clefts with negative predicates), but perform at chance level with passive voice constructions (and other "noncanonical" sentences such as object-gap relatives and object clefts). In the face of well-established results indicating that Broca's aphasics can exhibit several different performance patterns on these sentence types, Grodzinsky, Pi?ango, Zurif, and Drai (1999) argued that these conflicting results do not challenge the theory when the data are analyzed appropriately. They carried out a creative statistical analysis of the comprehension performance of published cases of Broca's aphasia and concluded that all of these cases are in agreement with the predicted pattern: chance on passives and 100% correct on actives. Here we show that the statistical reasoning adopted by Grodzinsky et al. (1999) is flawed. We also show that the comprehension performance of a substantial number of the Broca's aphasics in their own sample does not conform to the pattern required. Rather, contrary to these authors' claim, Broca's aphasia is not associated with a consistent pattern of sentence comprehension performance, but allows for a number of distinct patterns in different patients.     

Syntactic frame and verb bias in aphasia: plausibility judgments of undergoer-subject sentences

This study investigates three factors that have been argued to define "canonical form" in sentence comprehension: Syntactic structure, semantic role, and frequency of usage. We first examine the claim that sentences containing unaccusative verbs present difficulties analogous to those of passive sentences. Using a plausibility judgment task, we show that a mixed group of aphasics performed significantly better on unaccusatives than on passives. We then turn to the observation that passives are generally harder than actives for aphasics. We show that this effect is modulated by lexical bias, i.e., the likelihood that a verb appears in a given syntactic structure: Passives of passive-bias verbs were significantly easier than passives of active-bias verbs. More generally, sentences whose structure matches the lexical bias of the main verb are significantly easier than sentences in which structure and lexical bias do not match. These findings suggest that "canonical form" reflects frequency and lexical biases.     

Thematic analysis in agrammatic comprehension: syntactic structures and task demands.

Aphasics' ability to assign thematic roles during sentence comprehension was investigated. The study was motivated by the hypothesis that capacity limitations, e.g., due to slowed processing operations, interact systematically with certain aspects of structural analysis more than with others. Experiments using a sentence-picture matching paradigm were conducted with several agrammatic Broca's and paragrammatic Wernicke's patients. Experiment 1 tested comprehension of various syntatic structures. The astoundingly good performance in Experiment 1 for both patient groups was attributed to the low task demands of the experiment. Raising the task demands, by delaying presentation of the relevant picture set in Experiment 2, resulted in a significant decrement of comprehension performance for agrammatic Broca's aphasics, but not for Wernicke's aphasics. Putting the main verb in the sentence-final position, as in Experiment 3, affected Wernicke's aphasics', but not Broca's aphasics' performance. In principle, one explanation for the performance differences between Experiments 1 and 2 for Broca's patient might be a deficit in these patients' verbal memory capacity. Therefore, verbal memory span on different word categories was tested in an additional experiment. No difference, however, was found between the Broca's patients' and the Wernicke's patients' capacity for verbal memory despite their different sentence comprehension profiles. The present data are taken to support the view that Broca's aphasics' comprehension behavior is due to the processing demands imposed by structural inference chains and not to a general reduction in verbal memory.     

The Passive in 3- and 4-Year-Olds

This paper argues that analyzing the patterns of individual subject performance in tests of comprehension of passives might give insight into how little children interpret passives: 3 and 4 year-olds seem to go through a range of passive interpretation, that varies from actual comprehension to total non-comprehension. The fact that some small children understand long and short passives in Portuguese could be seen as evidence that the concept of universal delay for passives is too stringent. We also argue that below chance results and chance results may reflect a relevant difference in children’s behavior in interpreting the passive: below chance results seem to suggest that children interpret the passive as an active sentence.     

Comprehension of passives in Broca's aphasia

Drai and Grodzinsky have statistically analyzed a large corpus of data on the comprehension of passives by patients with Broca's aphasia. The data come, according to Drai and Grodzinsky, from binary choice tasks. Among the languages that are analyzed are Dutch and German. Drai and Grodzinsky argue that Dutch and German speaking Broca patients should be relatively good (that is, perform above chance) on comprehension of passive sentences, since in Dutch and German passives the relative order of the object and lexical verb is the underlying order and hence no movement takes place. We will demonstrate that both their linguistic arguments and their selection of Dutch data are invalid.     

Syntactic loss versus processing deficit: an assessment of two theories of agrammatism and syntactic comprehension deficits

This research evaluated Grodzinsky's (1984, 1986a) syntactic loss and Kolk and van Grunsven's (1985) working memory impairment explanations of syntactic comprehension deficits in agrammatic aphasics. Four aphasic patients were evaluated who showed different patterns of impairment on morphological and structural aspects of production. The comprehension tasks compared performance on full and truncated passive sentences. The syntactic loss hypothesis predicted worse performance on truncated than full passives, while the working memory deficit hypothesis predicted the reverse. Neither hypothesis was supported, as the patients performed at a similar level on both types of passives. In addition, there was little relation between the patients' production indices and their comprehension level. The results argue against any global theory of agrammatism that attempts to attribute all agrammatic speech and co-occurring syntactic comprehension deficits to the same source.     

The noun-verb problem in Chinese aphasia.

Previous studies have shown that Broca's aphasics experience a selective difficulty with action naming inside or outside of a sentence context. Conversely, it has been suggested that Wernicke's aphasics are particularly impaired in object naming. A number of explanations have been offered to account for this double dissociation, including grammatical accounts according to which the main verb problem in agrammatic Broca's aphasics is viewed as a by-product of their syntactic and/or morphological impairment, due perhaps to the greater morphological load carried by verbs (compared with nouns). In the Chinese language, there are no verb conjugations and no declensions. Hence there is no reason to expect a relationship between morphological impairment and deficits in action naming. We examined comprehension and production of object and action names, outside of a sentence context, in a sample of Chinese-speaking Broca's and Wernicke's aphasics. There was an interaction between patient group and object/action naming, but no corresponding interaction on the comprehension task. We conclude that action-naming deficits in Broca's aphasia (and/or the corresponding sparing of action names in Wernicke's aphasia) cannot be attributed to morphological differences between nouns and verbs. We also found a sublexical variant of the noun/verb dissociation applied to the internal structure of compound words made up of a verbal and a nominal element: Broca's aphasics tended to lexicalize the verbal portion of these words more often than the nominal compound, while Wernicke's showed the opposite pattern. These sublexical effects are difficult to explain in syntactic terms nor do they fit the standard lexical view. A modified lexical account is proposed, emphasizing semantic/conceptual effects in a distributed lexicon.     

Word order and finiteness in Dutch and English Broca's and Wernicke's aphasia

The effect of two linguistic factors in Broca's and Wernicke's aphasia was examined using Dutch and English subjects. Three tasks were used to test (1). the comprehension and (2). the construction of sentences, where verbs (in Dutch) and verb arguments (in Dutch and English) are in canonical versus non-canonical position; (3). the production of finite versus infinitive verbs. Proportions of errors as well as types of errors made by each aphasic group are similar on the sentence comprehension and sentence anagram tasks. On the verb production task the performance pattern is, again, the same, but the error types are different. The discussion focuses on how the similarities and differences across languages and across aphasia types may be interpreted with respect to the underlying deficit in Broca's and Wernicke's aphasia.     

The processing of extraposed structures in English

In most languages, most of the syntactic dependency relations found in any given sentence are projective: the word-word dependencies in the sentence do not cross each other. Some syntactic dependency relations, however, are non-projective: some of their word-word dependencies cross each other. Non-projective dependencies are both rarer and more computationally complex than projective dependencies; hence, it is of natural interest to investigate whether there are any processing costs specific to non-projective dependencies, and whether factors known to influence processing of projective dependencies also affect non-projective dependency processing. We report three self-paced reading studies, together with corpus and sentence completion studies, investigating the comprehension difficulty associated with the non-projective dependencies created by the extraposition of relative clauses in English. We find that extraposition over either verbs or prepositional phrases creates comprehension difficulty, and that this difficulty is consistent with probabilistic syntactic expectations estimated from corpora. Furthermore, we find that manipulating the expectation that a given noun will have a postmodifying relative clause can modulate and even neutralize the difficulty associated with extraposition. Our experiments rule out accounts based purely on derivational complexity and/or dependency locality in terms of linear positioning. Our results demonstrate that comprehenders maintain probabilistic syntactic expectations that persist beyond projective-dependency structures, and suggest that it may be possible to explain observed patterns of comprehension difficulty associated with extraposition entirely through probabilistic expectations.     

The existence of comprehension patterns in Broca's aphasia.

Berndt and Caramazza (1999) claim that Grodzinsky, Pi?ango, Zurif, and Drai (1999) were able to show a canonical-noncanonical difference (e.g., actives vs. passives) in the comprehension of Broca's aphasic patients only because of a patient selection bias. We show that the canonical-noncanonical comprehension pattern exists apart from any such bias, and that this pattern bears importantly on our understanding of the neuroanatomical organization of comprehension capacity at the sentence level.     

Is Passive Syntax Semantically Constrained? Evidence From Adult Grammaticality Judgment and Comprehension Studies

To explain the phenomenon that certain English verbs resist passivization (e.g., *£5 was cost by the book), Pinker (1989) proposed a semantic constraint on the passive in the adult grammar: The greater the extent to which a verb denotes an action where a patient is affected or acted upon, the greater the extent to which it is compatible with the passive. However, a number of comprehension and production priming studies have cast doubt upon this claim, finding no difference between highly affecting agent‐patient/theme‐experiencer passives (e.g., Wendy was kicked/frightened by Bob) and non‐actional experiencer theme passives (e.g., Wendy was heard by Bob). The present study provides evidence that a semantic constraint is psychologically real, and is readily observed when more fine‐grained independent and dependent measures are used (i.e., participant ratings of verb semantics, graded grammaticality judgments, and reaction time in a forced‐choice picture‐matching comprehension task). We conclude that a semantic constraint on the passive must be incorporated into accounts of the adult grammar.     

Patterns of comprehension performance in agrammatic Broca's aphasia: a test of the Trace Deletion Hypothesis

We tested the core prediction of the Trace Deletion Hypothesis (TDH) of agrammatic Broca's aphasia, which contends that such patients' comprehension performance is normal for active reversible sentences but at chance level for passive reversible sentences. We analyzed the comprehension performance of 38 Italian Broca's aphasics with verified damage to Broca's area, who completed sentence-to-picture matching tasks using active and passive reversible sentences as stimuli. The results failed to confirm the predictions made by TDH: only a small minority (15%) performed at chance on passive sentences and better than chance on active sentences. Furthermore, the distribution of the 38 subjects' performance on passive sentences differed from that predicted by the TDH since many more subjects performed at better-than-chance levels than expected. We discuss the implication of these results for claims about the distribution of language processing mechanisms in the brain.     

Perspective-taking and comprehension of passive sentences by Japanese-speaking children

This study demonstrates that children's difficulties in the interpretation of passives are attributed to their perspective-taking ability. Thirty-six Japanese preschool children participated in act-out sentence comprehension tasks. They were asked to manipulate two toy animals to demonstrate the meaning of two types of stimulus sentences: Type I had the child's toy, whose reference involved the child's actual name (e.g., Jun-kun no neko Jun's cat) encoded as grammatical subject, while Type II had the child's toy encoded as non-subject. Since passive structures take the perspective of the patient-denoting subject NP, it is assumed that only Type I passives have the perspective that matches that of the child.The results show that children's performance on passives was significantly better in Type I than in Type II sentences. But this difference was not observed for active sentences. For those who showed (nearly) perfect performance on active sentences, only Type I passives were equally well understood. These results strongly suggest that perspective-taking difficulties mask children's true competence on passives and that even 6-year-olds may not yet have attained the full perspective-taking ability required for comprehension of passive sentences.     

Verb processing during sentence comprehension in aphasia

This study examines verb processing during on-line sentence comprehension in aphasia. We describe two experiments that explore whether a group of Broca's aphasics, who were agrammatic in comprehension as well as speech, a group of fluent aphasics, and a group of normal controls are sensitive to the argument structure arrangements of verbs. Subjects had to perform a complex secondary task both in the immediate vicinity of the verb and also at a point well past the verb while listening to sentences for meaning. Reaction times to this secondary task show that both normal controls and agrammatic Broca's aphasic subjects activate multiple argument structure possibilities for a verb in the vicinity of the verb, yet at a point downstream from the verb such effects disappear. These data suggest that the problems agrammatic subjects show with verbs in sentence comprehension, and the general lexical access deficit also recently claimed to be part of the agrammatics' problem, may not extend to the real-time processing of verbs and their arguments. Fluent aphasic subjects, on the other hand, do not show sensitivity to the argument structure properties of verbs, suggesting that these patients may have a semantic-like sentence processing deficit.     

Filling gaps: Decision principles and structure in sentence comprehension

The correct grammatical characterization of sentences containing filler-gap dependencies is a topic of considerable theoretical interest in linguistics. In some grammatical frameworks, these dependencies are representef in terms of conditions on the permissible indexing of structures (or alternative structure evaluation conditions) which a representation must adhere to in order to be well-formed. In other frameworks, constraints on permissible filler-gap dependencies are simply inherent in the set of phrase structure rules contained in the grammar of a language.The processing of sentences with multiple (potential) filler-gap dependencies was investigated in two experiments. The first experiment provided evidence for three claims. First, the human sentence processor abides by a strategy of assigning the most recent potential filler to a gap. Hence, ‘recent filler’ sentences where this assignment proves to be correct takes less time to comprehend than ‘distant filler’ sentences where this decision turns out to be incorrect. Second, the recent filler strategy is itself just a special case of a more general strategy of assigning the most salient potential filler to a gap. Third, unambiguous sentences in which a filler-gap assignment is disambiguated by ‘control’ information specified by individual verbs gives rise to the same recent filler errors as ambiguous sentences. This suggests that tentative filler-gap assignments are made by the processor before all of the relevant constraints on permissible filler-gap dependencies are consulted by the processor.The second experiment tested an alternative hypothesis that the more complex ‘distant filler’ sentences took longer to comprehend in the first experiment only because these sentences often contained verbs which license two adjacent gaps. The experiment showed that there was a significant recent filler effect in sentences that did not contain adjacent gaps and that this effect did not interact with verb class.The finding that the processor delays use of verb-control information is extremely surprising. It may be explained by the fact that this information is only relevant to one type of gap (‘equi-gaps’) and what type of gap the processor is dealing with often can not be determined unambiguously at the time when it initially encounters a gap in its left-to-right processing of a sentence.If our interpretation of these findings is correct, they argue for a considerable amount of structure in the sentence comprehension system. Further, they favor a view of sentence processing in which processing operations involving constraints on the permissible indexing (or evaluation) of structures lag behind the processor's structure building operations. Hence, the results favor those grammatical theories which preserve this distinction over grammatical theories which provide a uniform characterization of all syntactic well-formedness conditions.     

Interpretation of pronouns in VP-ellipsis constructions in Dutch Broca's and Wernicke's aphasia

In this paper, we investigate the ability of Dutch agrammatic Broca's and Wernicke's aphasics to assign reference to possessive pronouns in elided VP constructions. The assumption is that the comprehension problems in these two populations have different sources that are revealed in distinct patterns of responses. The focus is primarily on the performance of the agrammatic group whose errors in comprehension are not viewed as a consequence of a breakdown of grammatical knowledge but as a result of limited processing resources (for an overview see Grodzinsky, 2000). The results of the present study provide evidence for the psycholinguistic reality of the economy hierarchy as proposed in the Primitives of Binding (Reuland, 2001). According to the economy hierarchy proposed for the non-brain-damaged, the more economical semantic dependencies are preferred over the costlier discourse dependencies. This hierarchy is reflected in agrammatic aphasia where the semantic dependencies are available on time and preferred over the discourse dependences that are not available on time as a result of the lack of processing resources with consequences for comprehension.