Aphasics'' sentence repetition behavior as a funciton of grammaticality

Twenty asphasics repeated grammatical and ungrammatical sentences. Ungrammatical sentences were characterized by violations of syntactic and/or semantic structure. Aphasics repeated accurately more grammatical than ungrammatical sentences. Ungrammatical sentences with violations of syntactic structure were repeated less accurately than those with preserved syntax. Aphasics' repetition errors were classified as: incorrect repetition, inapropriate correction, morphological error, lexical deletion and substitution responses. Repetition errors appeared to result from performance deficits, such as reduced retention span and physiological limitations of the speech musculature. Results suggest that asphasics are to some extent guided by a greater residual linguistic knowledge or competence than might be inferred from their spontaneous production.     

Performance of adult aphasics on a sentence evaluation and revision task

Adult aphasics completed a sentence evaluation and revision task to test some aspects of their linguistic competence. Grammatical and ungrammatical sentences served as the stimuli. Ungrammatical sentences were characterized by violations of syntactic or semantic structure, or both. Aphasics evaluated correctly the grammaticality of most stimulus sentences. Incorrect evaluations were associated with sentences characterized by violations of syntactic structure. Aphasics' revisions of sentences that they judged to be ungrammatical were in the direction of appropriate grammatical structures. Omission of morphological endings was the most frequent sentence revision error. Aphasics' errors on both tasks could be accounted for by performance deficits such as inattentiveness to syntactic detail, auditory perceptual impairments, and inefficient lexical retrieval. These findings lend support to the argument that aphasia is best characterized as a performance rather than competence disruption.     

Hemispheric differences in context sensitivity during lexical ambiguity resolution

Three experiments were conducted to investigate the influence of contextual constraint on lexical ambiguity resolution in the cerebral hemispheres. A cross-modal priming variant of the divided visual field task was utilized in which subjects heard sentences containing homonyms and made lexical decisions to targets semantically related to dominant and subordinate meanings. Experiment 1 showed priming in both hemispheres of dominant meanings for homonyms embedded in neutral sentence contexts. Experiment 2 showed priming in both hemispheres of dominant and subordinate meanings for homonyms embedded in sentence contexts that biased a central semantic feature of the subordinate meaning. Experiment 3 showed priming of dominant meanings in the left hemisphere (LH), and priming of the subordinate meaning in the right hemisphere (RH) for homonyms embedded in sentences that biased a peripheral semantic feature of the subordinate meaning. These results are consistent with a context-sensitive model of language processing that incorporates differential sensitivity to semantic relationships in the cerebral hemispheres.     

Right Hemisphere Sensitivity to Word- and Sentence-Level Context: Evidence From Event-Related Brain Potentials.

Researchers using lateralized stimuli have suggested that the left hemisphere is sensitive to sentence-level context, whereas the right hemisphere (RH) primarily processes word-level meaning. The authors investigated this message-blind RH model by measuring associative priming with event-related brain potentials (ERPs). For word pairs in isolation, associated words elicited more positive ERPs than unassociated words with similar magnitudes and onset latencies in both visual fields. Embedded in sentences, these same pairs showed large sentential context effects in both fields. Small effects of association were observed, confined to incongruous sentences after right visual hemifield presentation but present for both congruous and incongruous sentences after left visual hemifield presentation. Results do not support the message-blind RH model but do suggest hemispheric asymmetries in the use of word and sentence context during real-time processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lexical and sentence context effects in word recognition.

Three experiments examined lexical and sentence-level contributions to contextual facilitation effects in word recognition. Subjects named target words preceded by normal or scrambled sentence contexts that contained lexical associates of the target. In Experiment 1, normal sentences showed facilitation for related targets and inhibition for unrelated targets. Experiment 2 eliminated syntactically anomalous targets among unrelated items and showed only facilitation for related targets. In neither experiment was there any effect of relatedness for scrambled stimuli. Experiment 3 included syntactically normal but semantically anomalous sentences to test whether the failure of scrambled sentences to show priming was due to their syntactic incoherence. Normal sentences again showed contextual facilitation, but neither scrambled nor anomalous sentences showed such effects. The results indicate that there are sentence-context effects that do not arise solely from intralexical spreading activation and suggest that context facilitates the identification of a lexical candidate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structural and lexical constraints on filling gaps during sentence comprehension: A time-course analysis.

Reaction time and speed-accuracy trade-off procedures were used to examine when different linguistic constraints were operative in processing sentences with filler-gap dependencies. Experiments measured the time to assess the acceptability of structures with anomalous filler-gap dependencies stemming from violations of configuration (syntactic) constraints or local lexical constraints. Full time-course data indicate that configurational (island) constraints were operative 200–400 ms before local lexical constraints (i.e., subcategorization and thematic role restrictions). These results suggest that filler-gap assignments are determined by processes that appeal first to general syntactic information and only later to specific lexical information. The time-course data indicate that the parser does not posit potential gap sites within syntactic islands, which in turn motivates a restricted version of a first-resort model of filler-gap processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crystal structure of human serum albumin complexed with fatty acid reveals an asymmetric distribution of binding sites

A lexical decision experiment investigated hemisphere asymmetries in resolving lexical ambiguity within a sentence context. Sentences that biased a single meaning (either dominant or subordinate) of sentence-final ambiguous words were followed by a lateralized target related to the sentence-congruent or -incongruent meaning of the ambiguous word, or an unrelated word. In the RVF sentence-congruent targets were facilitated, while incongruent targets were not primed. In contrast, related targets were facilitated in the LVF, regardless of sentence context. This suggests that selecting the contextually appropriate word meaning requires the left hemisphere, and supports a right hemisphere role in maintaining alternate word senses.     

Eye movements of young and older adults during reading.

The eye movements of young and older adults were tracked as they read sentences varying in syntactic complexity. In Experiment 1, cleft object and object relative clause sentences were more difficult to process than cleft subject and subject relative clause sentences; however, older adults made many more regressions, resulting in increased regression path fixation times and total fixation times, than young adults while processing cleft object and object relative clause sentences. In Experiment 2, older adults experienced more difficulty than young adults while reading cleft and relative clause sentences with temporary syntactic ambiguities created by deleting the that complementizers. Regression analyses indicated that readers with smaller working memories need more regressions and longer fixation times to process cleft object and object relative clause sentences. These results suggest that age-associated declines in working memory do affect syntactic processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phonological phrase boundaries constrain the online syntactic analysis of spoken sentences.

Two experiments tested whether phonological phrase boundaries constrain online syntactic analysis in French. Pairs of homophones belonging to different syntactic categories (verb and adjective) were used to create sentences with a local syntactic ambiguity (e.g., [le petit chien mort], in English, the dead little dog, vs. [le petit chien] [mord], in English, the little dog bites, where brackets indicate phonological phrase boundaries). An expert speaker recorded the sentences with either a maximally informative prosody or a minimally informative one. Participants correctly assigned the appropriate syntactic category to the target word, even without any access to the lexical disambiguating information, in both a completion task (Experiment 1) and an abstract word detection task (Experiment 2). The size of the experimental effect was modulated by the prosodic manipulation (maximally vs. minimally informative), guaranteeing that prosody played a crucial role in disambiguation. The authors discuss the implications of these results for models of online speech perception and language acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Making sense of sentences in schizophrenia: Electrophysiological evidence for abnormal interactions between semantic and syntactic processing.

Event-related potentials to critical verbs were measured as patients with schizophrenia and healthy controls read sentences word by word. Relative to their preceding context, critical verbs were (a) congruous, (b) incongruous and semantically unrelated to individual preceding words (pragmatic-semantic violations), (c) incongruous but semantically related to individual preceding words (animacy-semantic violations), or (d) syntactically anomalous. The N400 was modulated normally in patients, suggesting that semantic integration between individual words within sentences was normal in schizophrenia. The amplitude of the P600 to both syntactic and animacy-semantic violations was reduced in patients relative to controls. The authors suggest that, in schizophrenia, an abnormality in combining semantic and syntactic information online to build up propositional meaning leaves sentence processing to be primarily driven by semantic relationships between individual words. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The dependence of lexical relatedness effects on syntactic connectedness.

Context effects on lexical decision were analyzed by manipulating lexical relatedness and syntactic connectedness. Related and unrelated word pairs were embedded in syntactic (e.g., "the author of this book/floor") and in scrambled (e.g., "the author the and book/floor") phrases. The sequences were presented serially and subjects made lexical decisions to the terminal targets. In four experiments, relatedness effects were substantial in syntactic phrases but only marginal in scrambled sequences. This result was unaffected by presentation rate or by blocking manipulations. A fifth experiment showed that the relatedness effect in syntactic phrases involved both facilitation of responses to related words and inhibition of responses to unrelated words. These results argue against a role for intralexical priming in on-line reading. They highlight the role of syntactic connectedness and suggest that contextual facilitation depends on the ease of integration of new words with the current text-level representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Categorical priming in the cerebral hemispheres: automatic in the left hemisphere, postlexical in the right hemisphere?

Automatic and postlexical semantic processing in the cerebral hemispheres was studied by presenting categorically related but nonassociated word pairs (e.g., TABLE-BED) to the left visual field (LVF) or to the right visual field (RVF) in semantic priming experiments. Experiment 1 examined automatic priming across stimulus onset asynchronies (SOAs) of 165 and 750 ms with a low proportion of related pairs and a low nonword ratio, employing a GO-NOGO lexical decision task. In contrast to an earlier view that a larger range of meanings is automatically activated in the right than in the left hemisphere, priming was observed in the RVF/left hemisphere only. SOA did not exert any effects. In Experiment 2, postlexical semantic matching of the prime and the target was encouraged by requiring subjects to respond to both of them at the same time. Now there was priming in the LVF, suggesting that a postlexical matching process works in the right hemisphere. The earlier studies showing a right hemisphere advantage in categorical priming are reinterpreted according to the postlexical right hemisphere hypothesis.     

The persistence of structural priming: Transient activation or implicit learning?

Structural priming in language production is a tendency to recreate a recently uttered syntactic structure in different words. This tendency can be seen independent of specific lexical items, thematic roles, or word sequences. Two alternative proposals about the mechanism behind structural priming include (a) short-term activation from a memory representation of a priming structure and (b) longer term adaptation within the cognitive mechanisms for creating sentences, as a form of procedural learning. Two experiments evaluated these hypotheses, focusing on the persistence of structural priming. Both experiments yielded priming that endured beyond adjacent sentences, persisting over 2 intervening sentences in Experiment 1 and over 10 in Experiment 2. Although memory may have short-term consequences for some components of this kind of priming, the persisting effects are more compatible with a learning account than a transient memory account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of time course and context on the facilitation of semantic features in the cerebral hemispheres.

Two divided visual field priming experiments were designed to determine the nature of lexical retrieval in the cerebral hemispheres by studying the facilitation of semantic features of unambiguous nouns. Unambiguous nouns have a single meaning, yet semantic features associated with these nouns may vary in the degree to which they are compatible with this single meaning (e.g., LAMB–WOOL as compared with LAMB–CHOPS). Results suggest that the left hemisphere selects both strongly and weakly associated semantic features that are compatible with the dominant representation of the noun. Dominance compatibility, rather than association strength, seems to be the more important factor for deciding what features are maintained in the left hemisphere. In contrast, the right hemisphere maintains more varied information, including features that are less compatible with the dominant representation (Experiment 1) and context information (Experiment 2). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Task demands and sentence comprehension in patients with dementia of the Alzheimer's type

Patients with dementia of the Alzheimer's type (DAT) and matched normal controls were given three tests of syntactic comprehension in which nonlinguistic visual and memory task demands were varied. In all tasks, subjects were presented spoken semantically reversible sentences with a variety of syntactic structures and required to match the sentence to a picture. In the first experiment, subjects matched the spoken sentence to one of two pictures that appeared either before or immediately following the presentation of the sentence. The target picture depicted the spoken sentence correctly and the foil depicted the reversed thematic roles to those in the sentence (i.e., it was a syntactic foil). The second experiment employed a sentence video-verification task in which subjects were required to determine if the spoken sentence matched a videotaped depiction of the action in the sentence or a syntactic foil. In the third experiment, in different conditions, subjects were required to determine whether the spoken sentence matched a single picture or to choose the picture that matched the sentence from an array of two or three pictures. In this experiment, both lexical and syntactic foils were used. In all tasks, DAT patients were affected by the number of propositions in the presented sentence, but not by the syntactic complexity of the sentence. Control subjects also were unaffected by the syntactic complexity of the sentence; the number-of-proposition effect was present in some experiments in the control population. Comparison of performance across the one-, two-, and three-picture versions of the task showed that the magnitude of the effect of number of propositions increased as the number of pictures in the array increased. In addition, analysis of the data from each of the tasks separately showed that the effect of number of propositions only occurred when subjects were attempting to match the target to a syntactic foil (one-picture version) or to choose between the target and a syntactic foil (two- and three-picture versions). The results support the view that patients with DAT do not have disturbances affecting syntactic processing. In addition, they suggest that the effect of number of propositions arises at a stage of analysis that is partially separate from assigning sentence meaning, such as in holding a representation of the sentence in memory until the pictures can be analyzed and encoded and/or in comparing the results of the picture analysis with a stored representation of the sentence meaning.     

Asymmetries in the preparation and control of manual aiming movements.

Conducted 2 experiments with 20 undergraduates to determine if typical right hand target aiming advantages could be reduced or eliminated by increasing the spatial demands of the aiming task. In Exp 1, right hand advantages were found for both movement time and error regardless of spatial characteristics of the task. When a greater degree of spatial uncertainty was introduced in Exp 2, Ss exhibited a left hand reaction time advantage. Taken together, results suggest that the right cerebral hemisphere may have a special role to play in preparing the spatial aspects of an aiming movement, while the left hemisphere is more important for movement execution. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The lexical nature of syntactic ambiguity resolution.

Ambiguity resolution is a central problem in language comprehension. Lexical and syntactic ambiguities are standardly assumed to involve different types of knowledge representations and be resolved by different mechanisms. An alternative account is provided in which both types of ambiguity derive from aspects of lexical representation and are resolved by the same processing mechanisms. Reinterpreting syntactic ambiguity resolution as a form of lexical ambiguity resolution obviates the need for special parsing principles to account for syntactic interpretation preferences, reconciles a number of apparently conflicting results concerning the roles of lexical and contextual information in sentence processing, explains differences among ambiguities in terms of ease of resolution, and provides a more unified account of language comprehension than was previously available. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Left hemisphere dysfunction and left hemisphere overactivation in schizophrenia.

Reports 2 experiments relating schizophrenia to functional brain asymmetry. In Exp I, 24 schizophrenics (mean age, 30.8 yrs) were compared to 24 matched controls (mean age, 37.3 yrs) on 2 tachistoscopic tasks (Syllable Test and Dot Location Test) designed to measure verbal and spatial information processing in the 2 hemispheres. Unlike the controls, the schizophrenics showed a right hemisphere superiority both on the verbal and on the spatial tests, indicating left hemisphere dysfunction in the initial processing of verbal information. In Exp II, lateral eye movements, as an index of contralateral hemispheric activation, were measured in a group of 24 paranoid schizophrenics (mean age, 28.9 yrs), 24 nonparanoid schizophrenics (mean age, 32.7 yrs), and 24 matched controls (mean age, 31.2 yrs). The eye movements were elicited by presenting the Ss with verbal neutral, verbal emotional, spatial neutral, and spatial emotional questions. The schizophrenics had significantly more rightward eye movement, compared to controls, regardless of question type, indicating left hemisphere overactivation. Results suggest that schizophrenia is associated with a pattern consisting of both left hemisphere dysfunction and overactivation. (63 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of language intervention on syntactic skill levels in preschoolers.

Questions concerning the role of input in the growth of syntactic skills have generated substantial debate within psychology and linguistics. The authors address these questions by investigating the effects of experimentally manipulated input on children's skill with the passive voice. The study involved 72 four-year-olds who listened to stories containing either a high proportion of passive voice sentences or a high proportion of active voice sentences. Following 10 story sessions, children's production and comprehension of passives were assessed. Intervention type affected performance--children who heard stories with passive sentences produced more passive constructions (and with fewer mistakes) and showed higher comprehension scores than children who heard stories with active sentences. Theoretical implications of these results for the understanding of the nature of syntactic skills and practical implications for the development of preschool materials are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)