Biomedical subjects

Dorothee J Chwilla

Publications and source records attributed to Dorothee J Chwilla.

9 recordsLinked to original sources

PubMed2006

The interplay of heuristics and parsing routines in sentence comprehension: evidence from ERPs and reaction times.

Semantic anomalies like "the fox that hunted the poacher" elicit P600 effects. Kolk et al. [Kolk, H.J., Chwilla, D.J., Van Herten, M., Oor, P.J.W., 2003. Structure and limited capacity in verbal working memory: a study with event related potentials. Brain and language, 85(1), 1-36] proposed that this P600 effect is triggered by a conflict between the outcome of a lexical strategy with that of the parsing routine. Specifically, when the lexical strategy indicates that the poacher hunted the fox, the full parse leads to the conclusion that the fox was the one who did the hunting. We tested this hypothesis by replicating the study cited above but manipulating the context by means of instruction. Participants were informed that semantic anomalies were created on purpose and that they should not be misled by these anomalies but instead focus on syntax or sentence structure. This instruction led to a strong reduction in P600 effect. This result supports the view that expectations play an important role in the generation of P600 effects to semantic anomalies, as proposed by Kolk et al. [Kolk, H.J., Chwilla, D.J., Van Herten, M., Oor, P.J.W., 2003. Structure and limited capacity in verbal working memory: a study with event related potentials. Brain and language, 85(1), 1-36].

Adolescent↗

PubMed2006

Monitoring in language perception: The effect of misspellings of words in highly constrained sentences.

We present evidence for a monitoring process in language perception at the word level, reflected by a P600. This P600 is triggered when a conflict evolves because the brain encounters an unexpected linguistic item when another item is highly expected. To resolve this conflict between representations, the brain monitors the input to check for possible processing errors. A P600 was hypothesized to occur after orthographic anomalies, like pseudohomophones, in particular when the word from which the pseudohomophone is derived is highly expected. This hypothesis was tested by recording ERPs while participants read high-cloze sentences ('In that library the pupils borrow books ....') and low-cloze sentences ('The pillows are stuffed with books ....'). In a pretest, the high-cloze sentences were produced by more than 90% of the subjects, while the low-cloze sentences were never produced. In half of the sentences, the critical word books was replaced by a pseudohomophone (e.g., bouks), which in the high-cloze sentences orthographically and phonologically resembles the highly expected word. Consistent with the monitoring hypothesis, only pseudohomophones in high-cloze sentences elicited a widely distributed P600 effect while pseudohomophones in low-cloze sentences did not. A standard N400 effect of cloze probability occurred both for words and pseudohomophones. The present ERP results support the view that there is a process of monitoring that takes place in language perception which is reflected by the P600. It occurs whenever a conflict between a strong tendency to accept and one to reject a word brings the cognitive system in state of indecision.

Adolescent↗

PubMed2006

When heuristics clash with parsing routines: ERP evidence for conflict monitoring in sentence perception.

Monitoring refers to a process of quality control designed to optimize behavioral outcome. Monitoring for action errors manifests itself in an error-related negativity in event-related potential (ERP) studies and in an increase in activity of the anterior cingulate in functional magnetic resonance imaging studies. Here we report evidence for a monitoring process in perception, in particular, language perception, manifesting itself in a late positivity in the ERP. This late positivity, the P600, appears to be triggered by a conflict between two interpretations, one delivered by the standard syntactic algorithm and one by a plausibility heuristic which combines individual word meanings in the most plausible way. To resolve this conflict, we propose that the brain reanalyzes the memory trace of the perceptual input to check for the possibility of a processing error. Thus, as in Experiment 1, when the reader is presented with semantically anomalous sentences such as, "The fox that shot the poacher...," full syntactic analysis indicates a semantic anomaly, whereas the word-based heuristic leads to a plausible interpretation, that of a poacher shooting a fox. That readers actually pursue such a word-based analysis is indicated by the fact that the usual ERP index of semantic anomaly, the so-called N400 effect, was absent in this case. A P600 effect appeared instead. In Experiment 2, we found that even when the word-based heuristic indicated that only part of the sentence was plausible (e.g., "...that the elephants pruned the trees"), a P600 effect was observed and the N400 effect of semantic anomaly was absent. It thus seems that the plausibility of part of the sentence (e.g., that of pruning trees) was sufficient to create a conflict with the implausible meaning of the sentence as a whole, giving rise to a monitoring response.

Adult↗

PubMed2005

Testing a model for bilingual semantic priming with interlingual homographs: RT and N400 effects.

Using a semantic priming paradigm, this study examines the effects of semantic and lexical-orthographic context on reaction times (RTs) and event-related potentials (ERPs) for interlingual homographs. Dutch-English bilinguals performed an English lexical decision task in which homographs like STEM (meaning "voice" in Dutch) were preceded by primes like ROOT or FOOL that were semantically related or unrelated to the English reading of the target word. Homographs were responded to faster following semantically related primes than following unrelated primes. The responses in both conditions were modulated by the relative frequencies of the two readings of the homographs: responses were faster when their English word frequency was high or when their Dutch word frequency was low. In the ERPs, N400 effects, taken to reflect processes of semantic integration, were found for homographs preceded by related primes. Remarkably, the amplitude of the N400 effect was also modulated by word frequency in both the first (Dutch, L1) and the second (English, L2) language. The observed relationship between lexical and semantic variables supports a model for bilingual semantic priming that extends the language nonselective BIA+ model for bilingual word recognition.

Adult↗

PubMed2005

Accessing world knowledge: evidence from N400 and reaction time priming.

How fast are we in accessing world knowledge? In two experiments, we tested for priming for word triplets that described a conceptual script (e.g., DIRECTOR-BRIBE-DISMISSAL) but were not associatively related and did not share a category relationship. Event-related brain potentials were used to track the time course at which script information becomes available. In Experiment 1, in which participants made lexical decisions, we found a facilitation for script-related relative to unrelated triplets, as indicated by (i) a decrease in both reaction time and errors, and (ii) an N400-like priming effect. In Experiment 2, we further explored the locus of script priming by increasing the contribution of meaning integration processes. The participants' task was to indicate whether the three words presented a plausible scenario. Again, an N400 script priming effect was obtained. Directing attention to script relations was effective in enhancing the N400 effect. The time course of the N400 effect was similar to that of the standard N400 effect to semantic relations. The present results show that script priming can be obtained in the visual modality, and that script information is immediately accessed and integrated with context. This supports the view that script information forms a central aspect of word meaning. The RT and N400 script priming effects reported in this article are problematic for most current semantic priming models, like spreading activation models, expectancy models, and task-specific semantic matching/integration models. They support a view in which there is no clear cutoff point between semantic knowledge and world knowledge.

Adult↗

PubMed2005

An ERP study of P600 effects elicited by semantic anomalies.

Syntactic anomalies reliably elicit P600 effects. Recent studies, however, reported P600 effects to semantic anomalies. These findings are difficult to reconcile with the common view on the P600 as a purely syntactic component. The present study--carried out in Dutch--tested the possibility that a P600 to semantic anomalies would nevertheless reflect syntactic processing. We presented semantic reversal anomalies in syntactically correct and unambiguous sentences, like #The cat that fled from the mice.... If participants would use a plausibility strategy and combine the lexical items in the most plausible way, they would--in the case of the example--assume that the mice were fleeing from the cat. Furthermore, this interpretation could lead them to expect a particular inflection of the verb (here: plural inflection). The violation of this expectation could have elicited the P600 effect. Such a syntactic mismatch can occur only in sentences in which the number of theme and agent are different. Therefore, in the present study, the number of theme and agent was either different or the same. A centroparietal P600 effect was present not only in different number sentences but also in same number sentences. Consequently, the P600 effect was not due to a syntactic mismatch, thereby challenging a purely syntactic account of the P600. An alternative view concerning the functional significance of the P600 is discussed, i.e., that it reflects a monitoring component that checks upon the veridicality of ones sentence perception.

Acoustic Stimulation↗

PubMed2003

Event-related potential and reaction time evidence for inhibition between alternative meanings of ambiguous words.

We investigated the effects of two primes that converged onto the same semantic target representation (e.g., LION-STRIPES-TIGER) or diverged onto different semantic target representations (e.g., KIDNEY-PIANO-ORGAN). Balota and Paul (1996) showed that the RT effects of two related primes in naming and lexical decision are additive, both for unambiguous and ambiguous words. Only in a relatedness judgment task ambiguous words showed underadditivity, whereas unambiguous words again showed additivity. This underadditivity was interpreted to reflect inhibition of alternative meanings of ambiguous words. In this article we tested whether inhibition occurs for N400, assumed to index postlexical integration. In lexical decision, we found additive N400 and RT effects for unambiguous and for ambiguous words. In a relatedness judgment task we observed differences between measures: (1) for unambiguous words overadditivity for N400 vs. additivity for RT; (2) although, for ambiguous words underadditivity occurred for N400 and RT, the effects were different. For RT, the alternative meaning was only less available, whereas for N400 the alternative meaning appeared completely unavailable. Our results have implications for our understanding of inhibitory processes in the processing of ambiguous words and for the functional significance of N400.

Adult↗

PubMed2003

Structure and limited capacity in verbal working memory: a study with event-related potentials.

In order to test recent claims about the structure of verbal working memory, two ERP experiments with Dutch speaking participants were carried out. We compared the ERP effects of syntactic and semantic mid-sentence anomalies in subject and object relative sentences. In Experiment 1, the participants made acceptability judgments, while in Experiment 2 they read for comprehension. Syntactic anomalies concerned subject-verb disagreement, while semantic anomalies were related to implausible events (e.g., *The cat that fled from the mice ran through the room). Semantic anomalies did not elicit an N400 effect. The semantic as well as syntactic anomalies elicited P600 effects, with similar centro-parietal scalp distributions. For both kinds of anomaly, the P600 effects were modulated by syntactic complexity: they were either relatively small (Experiment 1) or absent (Experiment 2) in object relative sentences. Taken together, our results suggest that: (a) verbal working memory is a limited capacity system; (b) it is not subdivided into an interpretative and a post-interpretative component (); (c) the P600 can reflect the presence of a semantic bias in syntactically unambiguous sentences; (d) the P600 is related to language monitoring: its function is to check upon the veridicality of an unexpected (linguistic) event; (e) if such a check is made, there is no integration of the event and hence no N400 effect.

Adolescent↗

PubMed2002

Three-step priming in lexical decision.

In two experiments, we investigated mediated two-step priming (e.g., from LION to STRIPES via TIGER) and three-step priming (e.g., from MANE to STRIPES via LION and TIGER). Experiment 1 showed robust two-step priming in the double lexical decision task. In Experiment 2, we tested for three-step priming and investigated the possibility that it is not association strength based on free association, but frequency of co-occurrence, that causes three-step priming. Co-occurrence has been proposed as a measure of familiarity and semantic relatedness. Significant three-step priming was obtained. Lexical co-occurrence could not account for the effect. However, a more global measure of semantic similarity that includes the similarity of the contexts in which concepts occur revealed that the three-step pairs were semantically related. If this global measure provides a proper estimate of the semantic relatedness of our items, then three-step priming is consistent not only with spreading activation models, but also with distributed memory models and the compound cue model.

Decision Making↗