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Results for “semantic path analysis”

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PubMed2002

Semantic geodesic maps: a unifying geometrical approach for studying the structure and dynamics of single trial evoked responses.

OBJECTIVES: A general framework for identifying and describing structure in a given sample of evoked response single-trial signals (STs) is introduced. The approach is based on conceptually simple geometrical ideas and enables the convergence of pattern analysis and non-linear time series analysis. METHODS: Classical steps for analyzing the STs by waveform are first employed and the ST-analysis is transferred to a multidimensional space, the feature space, the geometry of which is systematically studied via multidimensional scaling (MDS) techniques giving rise to semantic maps. The structure in the feature space characterizes the trial-to-trial variability and this is utilized to probe functional connectivity between two brain areas. The underlying dynamic process responsible for the emerged structure can be described by a multidimensional trajectory in the feature space. This in turn enables the detection of dynamical interareal coupling as similarity between the corresponding trajectories. RESULTS AND CONCLUSIONS: The utility of semantic maps was demonstrated using magnetoencephalographic data from a simple auditory paradigm. The coupling of ongoing activity and evoked response is vividly demonstrated and contrasted with the apparent deflection from zero baseline that survives averaging. Prototypes are easily identified as the end points of distinct paths in the semantic map representation, and their neighborhood is populated by STs with distinct properties not only in the latencies where the evoked response is expected to be strong, but also and very significantly in the prestimulus period. Finally our results provide evidence for interhemispheric binding in the (4-8 Hz) range and dynamical coupling at faster time scales.

Brain Mapping↗

PubMed1994

Brain potentials elicited by garden-path sentences: evidence of the application of verb information during parsing.

Event-related potentials were recorded from 13 scalp locations while participants read sentences containing a syntactic ambiguity. In Experiment 1, syntactically disambiguating words that were inconsistent with the "favored" syntactic analysis elicited a positive-going brain potential (P600). Experiment 2 examined whether syntactic ambiguities are resolved by application of a phrase-structure-based minimal attachment principle or by word-specific subcategorization information. P600 amplitude was a function of subcategorization biases rather than syntactic complexity. These findings indicate that such biases exist and can influence the parser under certain conditions and that P600 amplitude is a function of the perceived syntactic well-formedness of the sentence.

Adolescent↗

PubMed1994

Schizophrenia and temporal lobe epilepsy. A neuropsychological analysis.

BACKGROUND: Recent neuroimaging studies have reported structural abnormalities of mesial temporal lobe structures in schizophrenia. This study compared the neuropsychological performance of patients with schizophrenia with patients with either left or right temporal lobe epilepsy to determine if lateralized, developmental temporal lobe dysfunction provides a model of the cognitive impairments observed in schizophrenia. METHODS: A total 66 patients with schizophrenia and 101 patients with medically intractable focal temporal lobe epilepsy (48 left temporal, 53 right temporal) received a comprehensive neuropsychological battery. RESULTS: The three groups did not differ on age, years of education, or Full-Scale IQ. However, clear differences were noted in performance profiles. Patients with schizophrenia scored significantly higher than either epilepsy group on a measure of word reading thought to reflect premorbid competence. Patients with schizophrenia demonstrated greater attentional impairment and motor slowing than either epilepsy group. The patients with schizophrenia had superior semantic knowledge and verbal memory compared with the left temporal lobe group. On the Wisconsin Card Sorting Test the patients with schizophrenia obtained significantly fewer categories than either temporal lobe group, but were not significantly more perseverative. CONCLUSIONS: Data suggest lateralized temporal lobe dysfunction does not provide an adequate model of the cognitive impairments seen in schizophrenia. The disorders seem to follow different developmental paths: In early-onset epilepsy, the acquisition of cognitive skills and academic knowledge is compromised, while in schizophrenia cognitive functions are lost. Extratemporal pathologic features, most likely of the frontal lobe, are implicated in the cognitive dysfunction of schizophrenia.

Adult↗

PubMedDate not supplied

A comparison of two reading interventions for children with reading disabilities.

This study compared the effectiveness of two reading interventions in a public school setting. Forty-five second-grade children with reading disabilities were randomly assigned to a 6-week phonological awareness, word analogy, or math-training program. The two reading interventions differed from each other in (a) the unit of word analysis (phoneme versus onset-rime), (b) the approach to intervention (contextualized versus decontextualized), and (c) the primary domain of reading instruction (oral versus written language). Results indicate that children in both reading programs achieved significant gains in beginning reading skills, learning the specific skills taught in their respective programs, and applying what they had learned to uninstructed material on several transfer-of-learning measures, in comparison to children in the control group. For children in both reading intervention groups, the most significant mediator of growth in oral reading fluency was a child's initial level of word identification skill. Implications of these findings are that systematic, high quality reading intervention can occur in a small group, public school setting and that there are several different paths to the remediation of children with reading disabilities.

Child↗

PubMed2001

Thematic roles assigned along the garden path linger.

In the literature dealing with the reanalysis of garden path sentences such as While the man hunted the deer ran into the woods, it is generally assumed either that people completely repair their initial incorrect syntactic representations to yield a final interpretation whose syntactic structure is fully consistent with the input string or that the parse fails. In a series of five experiments, we explored the possibility that partial reanalyses take place. Specifically, we examined the conditions under which part of the initial incorrect analysis persists at the same time that part of the correct final analysis is constructed. In Experiments 1a and 1b, we found that both the length of the ambiguous region and the plausibility of the ultimate interpretation affected the likelihood that such sentences would be fully reanalyzed. In Experiment 2, we compared garden path sentences with non-garden path sentences and compared performance on two different types of comprehension questions. In Experiments 3a and 3b, we constructed garden path sentences using a small class of syntactically unique verbs to provide converging evidence against the position that people employ some sort of "general reasoning" or pragmatic inference when faced with syntactically difficult garden paths. The results from these experiments indicate that reanalysis of such sentences is not always complete, so that comprehenders often derive an interpretation for the full sentence in which part of the initial misanalysis persists. We conclude that the goal of language processing is not always to create an idealized structure, but rather to create a representation that is "good enough" to satisfy the comprehender that an appropriate interpretation has been obtained.

Cognition↗

PubMed1993

Processing Dutch sentence structures.

This paper summarizes existing research on syntactic processing of Dutch sentences by adult native speakers of the language, with an eye to the implications of this work for a general theory of the human sentence processing mechanism (HSPM). The principles underlying the assignment of phrase structure and the binding of traces seem to be the same as those proposed for languages like English or Italian. For example, no delays of analysis exist in parsing the constituents of a phrase even if the phrase is head-final. Also, the obligatory topicalization of a constituent which is required in the highest clause of a Dutch sentence does not appear to result in trace postulation principles distinct from those operative in languages where topicalization is optional. The studies reviewed also address questions concerning the complexity of the dependency between a moved constituent and its trace as measured by the length of a path vs. the length of a chain, the processing of subject gaps following an overt complementizer, the complexity of interpreting an adjunct moved from an obligatory position, and the processing of discontinuous words. Though the studies do not pose a problem for pre-existing views of the HSPM, they do highlight certain areas of parsing theory which remain seriously underdeveloped. Foremost, perhaps, is the specification of the principles governing the architecture of the processing system, which ultimately should explain how the organization of the HSPM and its subcomponents results from acquiring the grammar of any particular language.

Animals↗

PubMed1997

Language and Williams syndrome: how intact is "intact"?

It has been claimed that Williams syndrome (WS), a rare neurodevelopmental disorder, is characterized by serious cognitive deficits alongside intact language. The syndrome is often used as a prime example of the modularity of an innate faculty for morphosyntactic rules. We challenge this claim and hypothesize that morphosyntax, although surprisingly good given WS level of mental retardation, is by no means intact. We make an initial test of this hypothesis through an analysis of the receptive language of a group of English-speaking WS individuals on a standardized morphosyntactic test. We then present an experimental study of expressive language that examines grammatical gender assignment in French-speaking WS patients. Despite a Verbal Mental Age selected to be higher than the chronological age of the young control group, these people with WS continue even in adulthood to show clear-cut deficits in their production of an aspect of morphosyntax that normal children acquire effortlessly very early. The results of the 2 studies, one focusing on receptive language and the other on expressive language, challenge the notion that comprehension and use of morphosyntactic rules in WS individuals are intact. The Within-domain dissociations regarding the use of grammatical gender assignment across several sentence clements and their difficulties in understanding embedded sentences-two quintessentially linguistic skills-suggest that we must rethink the notion of spared, modular, language capacities in Williams syndrome. We conclude that WS language follows a different path to normal acquisition and may turn out to be more like second language learning.

Adolescent↗