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A D Friederici

Publications and source records attributed to A D Friederici.

At least 73 records · Page 4Linked to original sources
PubMed1996

Attention and mental performance in confinement: evidence from cognitive psychophysiology.

In summary, the results provide several lines of evidence for the assumption that confinement and isolation for a period of 60 days attenuate attentional capacity differentially during auditory classification: the extraction of information from low probability events, but not from high probability events, is decreased by attentional limitations. With the advent of automatic control systems there is an increasing number of operations which require the monitoring of information sources for low probability critical stimuli for extended periods of time. Given the functional similarities of the task employed in this study and the monitoring tasks in practical settings, the results of this study should be considered as a human factor concern for control operations taking place under conditions of confinement and isolation.

Adult↗
PubMed1996

Temporal structure of syntactic parsing: early and late event-related brain potential effects.

Event-related brain potentials (ERPs) were recorded from participants listening to or reading sentences that were correct, contained a violation of the required syntactic category, or contained a syntactic-category ambiguity. When sentences were presented auditorily (Experiment 1), there was an early left anterior negativity for syntactic-category violations, but not for syntactic-category ambiguities. Both anomaly types elicited a late centroparietally distributed positivity. When sentences were presented visually word by word (Experiment 2), again an early left anterior negativity was found only for syntactic-category violations, and both types of anomalies elicited a late positivity. The combined data are taken to be consistent with a 2-stage model of parsing, including a 1st stage, during which an initial phrase structure is built and a 2nd stage, during which thematic role assignment and, if necessary, reanalysis takes place. Disruptions to the 1st stage of syntactic parsing appear to be correlated with an early left anterior negativity, whereas disruptions to the 2nd stage might be correlated with a late posterior distributed positivity.

Adult↗
PubMed1996

Oscillatory neuromagnetic activity induced by language and non-language stimuli.

Event-related oscillatory brain activity during language perception differs from activity occurring during the processing of comparable non-language stimuli. This fact became apparent in the observation of changes in the normalized spectral power of magnetoencephalographic (MEG) signals during the subject's processing of these stimuli. MEG was recorded over the left and right hemispheres of 12 right-handed subjects. During the experimental session, bisyllablic content words and physically similar non-language stimuli were presented with equal probability in a randomized order in either the visual or auditory modality. Approximately 15% of these stimuli were marked and the subject's task was to detect these marked stimuli. As a major characteristic of language vs. non-language processing, we obtained an enhancement of the normalized spectral power around 240 ins in the 60-65-Hz band over the left hemisphere for the language condition and over the right hemisphere for the non-language condition, independent of the modality of stimulus presentation. Starting at approximately the same latency but in lower-frequency bands (15-45-Hz), an extended (250-600 ms) reduction of normalized spectral power was observed. This reduction, although it generally confirmed previous results, differed in the no hemisphere-specific reduction was found for the processing of words. A domain-specific enhancement of normalized spectral power was also evident around 800-1200 ms in the 15-30-Hz band. In the auditory condition, this enhancement of the normalized spectral power was larger after the presentation of language stimuli whereas in the visual condition a larger enhancement of the normalized spectral power was obtained after presentation of non-language stimuli. As this latter effect appears relatively late after the stimulus onset and differs in expression for both modalities of stimulus presentation, a simple relationship between language perception and oscillatory brain dynamics can be excluded for this enhancement. In contrast, the left hemispheric enhancement of the normalized spectral power present around 240 ms in the 60-65-Hz band seems to reflect oscillatory pattern specific to the processing of words.

Acoustic Stimulation↗
PubMed1995

The time course of syntactic activation during language processing: a model based on neuropsychological and neurophysiological data.

This paper presents a model describing the temporal and neurotopological structure of syntactic processes during comprehension. It postulates three distinct phases of language comprehension, two of which are primarily syntactic in nature. During the first phase the parser assigns the initial syntactic structure on the basis of word category information. These early structural processes are assumed to be subserved by the anterior parts of the left hemisphere, as event-related brain potentials show this area to be maximally activated when phrase structure violations are processed and as circumscribed lesions in this area lead to an impairment of the on-line structural assignment. During the second phase lexical-semantic and verb-argument structure information is processed. This phase is neurophysiologically manifest in a negative component in the event-related brain potential around 400 ms after stimulus onset which is distributed over the left and right temporo-parietal areas when lexical-semantic information is processed and over left anterior areas when verb-argument structure information is processed. During the third phase the parser tries to map the initial syntactic structure onto the available lexical-semantic and verb-argument structure information. In case of an unsuccessful match between the two types of information reanalyses may become necessary. These processes of structural reanalysis are correlated with a centroparietally distributed late positive component in the event-related brain potential.(ABSTRACT TRUNCATED AT 250 WORDS)

Aphasia, Broca↗
PubMed1995

Processing relative clauses varying on syntactic and semantic dimensions: an analysis with event-related potentials.

Event-related potentials were used to study how parsing of German relative clauses is influenced by semantic information. Subjects read well-formed sentences containing either a subject or an object relative clause and answered questions concerning the thematic roles expressed in those sentences. Half of the sentences contained past participles that on grounds of semantic plausibility biased either a subject or an object relative reading; the other half contained past participles that provided no semantic information favoring either reading. The past participle elicited an N400 component, larger in amplitude for neutral than for semantically biased verbs, but this occurred only in the case of subject relative clauses. More specific effects were obtained only for a subgroup of subjects, when these were grouped into fast and slow comprehenders on the basis of their question-answering reaction times. Fast comprehenders showed larger N400 amplitudes for neutral than for semantically biased past participles in general and larger N400s for the latter when there was a bias for an object relative reading as opposed to a subject relative reading. Syntactic ambiguity resolution, indicated by an auxiliary in sentence final position, was associated in this subgroup with a positive component (P345), larger in amplitude for auxiliaries indicating an object relative reading than for those indicating a subject relative reading. The latter component was independent of semantically biasing information given by a preceding past participle. Implications of these findings for models of language comprehension are considered.

Adult↗
PubMed1994

Processing articles and pronouns in agrammatic aphasia: evidence from French.

The hypothesis that closed-class items which participate in theta-role assignment are less problematic in agrammatism than items which do not (Rizzi, 1985) is put to an empirical test. Five French-speaking agrammatic patients were tested in a sentence-picture matching paradigm to probe their comprehension of sentences containing articles, which are not involved in theta-role assignment, and of sentences containing pronouns, which in the direct object position are homophonous with articles and are theta-role assignees. Gender was used as a variable to differentiate between target and distractor. The data indicate that pronouns are significantly more difficult to process than articles. This result disconfirms the claim that the availability of grammatical information encoded in closed-class items is a function of their involvement in theta-role assignment. The present study demonstrates that the ability to process gender marked articles is generally well preserved in French-speaking agrammatic patients.

Adult↗
PubMed1993

Event-related brain potentials during natural speech processing: effects of semantic, morphological and syntactic violations.

The present study investigated different aspects of auditory language comprehension. The sentences which were presented as connected speech were either correct or incorrect including a semantic error (selectional restriction), a morphological error (verb inflection), or a syntactic error (phrase structure). After each sentence, a probe word was presented auditorily, and subjects had to decide whether this word was part of the preceding sentence or not. Event-related brain potentials (ERPs) were recorded from 7 scalp electrodes. The ERPs evoked by incorrect sentences differed significantly from the correct ones as a function of error type. Semantic anomalies evoked a 'classical' N400 pattern. Morphological errors elicited a pronounced negativity between 300 and 600 ms followed by a late positivity. Syntactic errors, in contrast, evoked an early negativity peaking around 180 ms followed by a negativity around 400 ms. The early negativity was only significant over the left anterior electrode. The present data demonstrate that linguistic errors of different categories evoke different ERP patterns. They indicate that with using connected speech as input, different aspects of language comprehension processes cannot only be described with respect to their temporal structure, but eventually also with respect to possible brain systems subserving these processes.

Adult↗
PubMed1993

Phonotactic knowledge of word boundaries and its use in infant speech perception.

The development of a lexicon critically depends on the infant's ability to identify wordlike units in the auditory speech input. The present study investigated at what age infants become sensitive to language-specific phonotactic features that signal word boundaries and to what extent they are able to use this knowledge to segment speech input. Experiment 1 showed that infants at the age of 9 months were sensitive to the phonotactic structure of word boundaries when word-like units were presented in isolation. Experiments 2 to 5 demonstrated that this sensitivity was present even when critical items were presented in context, although only under certain conditions. Preferences for legal over illegal word boundary clusters were found when critical items were embedded in two identical syllables, keeping language processing requirements and attentional requirements low. Experiment 6 replicated the findings of Experiment 1. Experiment 7 was a low-pass-filtered version of Experiment 6 that left the prosody of the stimulus items intact while removing most of the distinctive phonotactic cues. As expected, no listening preference for legal over illegal word boundary clusters was found in this experiment. This clearly suggests that the preferential patterns observed can be attributed to the infants' sensitivity to phonotactic constraints on word boundaries in a given language and not to suprasegmental cues.

Acoustic Stimulation↗
PubMed1992

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.

Adult↗
PubMed1992

Sensitivity to inflectional morphology in aphasia: a real-time processing perspective.

The present study investigates Broca's aphasics' sensitivity to morphological information in an on-line task. German is used as the test language because it is highly inflected. Results from two word monitoring experiments show first that Broca's patients like normal controls are sensitive to the presence of a contextually incorrect inflection. Contrary to normals, they are, however, not sensitive to the absence of an obligatory inflection even when its presence is syntactically highly constrained. Second, they reveal that Broca's aphasics are only sensitive to the presence of an incorrect inflection when it functions as a marker of lexical category (noun vs. verb) and not when it functions as a diacritical marker (second person singular vs. third person singular). The results are taken as evidence for the claim that Broca's aphasics are impaired in the ability to process the full syntactic information encoded in closed class elements in a fast, automatic, and obligatory way.

Adult↗
PubMed1991

Pronoun comprehension in aphasia: a comparison of three languages.

The research reported here investigated the effect of phonological and syntactic factors on the processing of pronouns by aphasics. The comprehension of these "closed-class" elements was studied in three different languages: French, Dutch, and German. The cross-linguistic design made it possible to vary phonological status (clitic/nonclitic) and phrasal category (noun phrase/prepositional phrase) as well as grammatical relation (direct/indirect object) while keeping class membership (closed class) and meaning constant. A sentence-picture matching task was given to 20 German-speaking, 16 Dutch-speaking, and 14 French-speaking aphasics, half of each language group being classified as agrammatic Broca's and half as paragrammatic Wernicke's aphasics. The results suggest that Broca's aphasics' limitations in retrieving pronouns, and therefore other closed-class elements, are not a function of either phonological status, phrasal category, or grammatical relation. These subjects' observed high level of performance on pronouns in language comprehension appears due to the kind of semantic and syntactic information they encode. Our findings indicate that a more refined distinction than closed class vs. open class is necessary.

Aphasia, Broca↗
PubMed1990

Spatial reference in weightlessness: perceptual factors and mental representations.

The role of gravity in spatial coordinate assignment and the mental representation of space were studied in three experiments, varying different perceptual cues systematically: the retinal, the visual background, the vestibular, and proprioceptive information. Verbal descriptions of visually presented arrays were required under different head positions (straight/tilt) and under different gravitational conditions (gravity present/gravity absent). The results of two experiments conducted with 2 subjects who participated in a space flight revealed that subjects are able to adequately assign positions in space in the absence of gravitational information, and that they do this by using their head-retinal coordinates as primary references. This indicates that they cognitively adapted to the perceptually new situation. The findings from a third experiment conducted with a larger group of subjects under a condition in which the gravitational information was present but irrelevant to the task being solved (subjects were in a horizontal supine position) show that subjects, in general, are flexible in using cues other than gravitational ones as references when the latter cannot serve as a referential system. These findings, together with the observation that consistent spatial assignment is possible even immediately after first exposure to the perceptually totally novel situation of weightlessness, seem to suggest that the mental representation of space, onto which given perceptual information is mapped, is independent of a particular percept.

Adult↗
PubMed1988

On the preservation of word order in aphasia: cross-linguistic evidence.

Studies of language production in English-speaking aphasics (both fluent and nonfluent) generally lead to the conclusion that word order is preserved to a much greater degree than grammatical morphology and/or lexical retrieval. However, because word order is rigidly preserved even in normal English speech, this pattern might reflect nothing more than "the weak link in the chain." Using a constrained production paradigm, we provide evidence showing that canonical sentence order is well preserved in both fluent and nonfluent patients, in Italian and German (languages that permit much more pragmatic word-order variation) as well as English. Patients also retain the ability to order nouns around a preposition, and among Italian patients, access to a high-frequency form of pragmatic word-order variation is also retained. Syntactic difficulties seem to revolve not around loss of ordering principles, but (1) reduction in syntactic complexity, (2) overuse of canonical word order as a "safe harbor," (3) blend errors in which a form appears in legal but semantically incorrect position, and (4) abandonment of the effort to produce a complete sentence under stressful conditions. We offer a redefinition of syntactic impairment as a problem in the access of phrase structure types, resulting in a preference for higher frequency forms. Parallels between lexical retrieval and phrase structure retrieval suggest that similar mechanisms may be at work in both cases.

Adolescent↗
PubMed1987

Processing passive sentences in aphasia: deficits and strategies.

Broca's and Wernicke's aphasics' ability to process passive sentences in the absence of semantic cues was investigated in an experiment which varies syntactic complexity and word order. The results indicate that Broca and Wernicke patients use different strategies for sentence comprehension. Wernicke patients use rather general strategies for interpretation, which assign syntactic function according to sequential arrangements of words. Broca's aphasics, by contrast, base their interpretation on specific structural elements of the sentence's surface form, without, however, being able to exploit the full syntactic information of these elements. The different strategies are interpreted to reflect differential underlying deficits.

Anomia↗
PubMed1987

Resolving perceptual conflicts: the cognitive mechanism of spatial orientation.

The cognitive mechanisms of spatial orientation were studied in an experiment varying different perceptual cues systematically: the retinal, the visual background, the vestibular, and the somatosensory information. Verbal descriptions of visually presented arrays were required under different head positions (straight/tilt) and under different gravity conditions (1 G/micro G). Results for two subjects clearly show that different coordinate systems are used under the two gravity conditions. Under 1 G it is the gravitational vertical which is chosen for primary reference, whereas under microgravity retinal information is primary. Conflicts between competing pieces of sensory information are solved by weighting the perceptual cues differently. The finding that consistent assignment can be made immediately after first exposure to weightlessness indicates that mental representations of space can be used independently of perceptual input parameters.

Cognition↗
PubMed1985

Strategy and impairment in sentence understanding by Broca's and Wernicke's aphasics.

15 Broca's aphasics and 14 Wernicke's aphasics, both German and Dutch speaking patients, were presented with a sentence-picture matching task. Both syntactic and semantic distractor pictures were used. Sentences were either reversible or non-reversible, had a topicalized or a non-topicalized word order and contained either of three types of prepositions that were labelled 'syntactic' (case-marking), 'obligatory' (subcategorized) and 'lexical' (locative). Results indicated (a) a significant difference between reversible and non reversible sentences for both Broca's and Wernicke's; (b) no significant differences between these two groups in the differences scores reversible minus non-reversible; (c) an above-chance performance on reversible sentences for both groups. To explain the pattern of differences between the various types of sentences, two schemes of interpretation are presented. The first scheme assumes that both Broca's and Wernicke's have lost basic (but different) syntactic abilities and that they can understand reversible sentences by non-syntactic strategies only. The second scheme assumes that there is no such loss, but that the impairment in Broca's and Wernicke's aphasia is such that the more syntactic analysis is required, the more errors are made. Patients are assumed to approach this task by trying to limit their syntactic analysis to the beginning of the sentence.

Adult↗