Displaying 1 - 7 of 7
  • Carota, F., Nili, H., Pulvermüller, F., & Kriegeskorte, N. (2021). Distinct fronto-temporal substrates of distributional and taxonomic similarity among words: Evidence from RSA of BOLD signals. NeuroImage, 224: 117408. doi:10.1016/j.neuroimage.2020.117408.

    Abstract

    A class of semantic theories defines concepts in terms of statistical distributions of lexical items, basing meaning on vectors of word co-occurrence frequencies. A different approach emphasizes abstract hierarchical taxonomic relationships among concepts. However, the functional relevance of these different accounts and how they capture information-encoding of meaning in the brain still remains elusive. We investigated to what extent distributional and taxonomic models explained word-elicited neural responses using cross-validated representational similarity analysis (RSA) of functional magnetic resonance imaging (fMRI) and novel model comparisons. Our findings show that the brain encodes both types of semantic similarities, but in distinct cortical regions. Posterior middle temporal regions reflected word links based on hierarchical taxonomies, along with the action-relatedness of the semantic word categories. In contrast, distributional semantics best predicted the representational patterns in left inferior frontal gyrus (LIFG, BA 47). Both representations coexisted in angular gyrus supporting semantic binding and integration. These results reveal that neuronal networks with distinct cortical distributions across higher-order association cortex encode different representational properties of word meanings. Taxonomy may shape long-term lexical-semantic representations in memory consistently with sensorimotor details of semantic categories, whilst distributional knowledge in the LIFG (BA 47) enable semantic combinatorics in the context of language use. Our approach helps to elucidate the nature of semantic representations essential for understanding human language.
  • Lemhöfer, K., Schriefers, H., & Indefrey, P. (2020). Syntactic processing in L2 depends on perceived reliability of the input: Evidence from P600 responses to correct input. Journal of Experimental Psychology: Learning, Memory, and Cognition, 46(10), 1948-1965. doi:10.1037/xlm0000895.

    Abstract

    In 3 ERP experiments, we investigated how experienced L2 speakers process natural and correct syntactic input that deviates from their own, sometimes incorrect, syntactic representations. Our previous study (Lemhöfer, Schriefers, & Indefrey, 2014) had shown that L2 speakers do engage in native-like syntactic processing of gender agreement but base this processing on their own idiosyncratic (and sometimes incorrect) grammars. However, as in other standard ERP studies, but different from realistic L2 input, the materials in that study contained a large proportion of incorrect sentences. In the present study, German speakers of Dutch read exclusively objectively correct Dutch sentences that did or did not contain subjective determiner “errors” (e.g., de boot “the boat,” which conflicts with the intuition of many German speakers that the correct phrase should be het boot). During reading for comprehension (Experiment 1), no syntax-related ERP responses for subjectively incorrect compared to correct phrases were observed. The same was true even when participants explicitly attended to and learned from the determiners in the sentences (Experiment 2). Only when participants judged the correctness of determiners in each sentence (Experiment 3) did a clear P600 appear. These results suggest that the full and native-like use of subjective grammars, as reflected in the P600 to subjective violations, occurs only when speakers have reason to mistrust the grammaticality of the input, either because of the nature of the task (grammaticality judgments) or because of the salient presence of incorrect sentences.
  • Bekemeier, N., Brenner, D., Klepp, A., Biermann-Ruben, K., & Indefrey, P. (2019). Electrophysiological correlates of concept type shifts. PLoS One, 14(3): e0212624. doi:10.1371/journal.pone.0212624.

    Abstract

    A recent semantic theory of nominal concepts by Löbner [1] posits that–due to their inherent uniqueness and relationality properties–noun concepts can be classified into four concept types (CTs): sortal, individual, relational, functional. For sortal nouns the default determination is indefinite (a stone), for individual nouns it is definite (the sun), for relational and functional nouns it is possessive (his ear, his father). Incongruent determination leads to a concept type shift: his father (functional concept: unique, relational)–a father (sortal concept: non-unique, non-relational). Behavioral studies on CT shifts have demonstrated a CT congruence effect, with congruent determiners triggering faster lexical decision times on the subsequent noun than incongruent ones [2, 3]. The present ERP study investigated electrophysiological correlates of congruent and incongruent determination in German noun phrases, and specifically, whether the CT congruence effect could be indexed by such classic ERP components as N400, LAN or P600. If incongruent determination affects the lexical retrieval or semantic integration of the noun, it should be reflected in the amplitude of the N400 component. If, however, CT congruence is processed by the same neuronal mechanisms that underlie morphosyntactic processing, incongruent determination should trigger LAN or/and P600. These predictions were tested in two ERP studies. In Experiment 1, participants just listened to noun phrases. In Experiment 2, they performed a wellformedness judgment task. The processing of (in)congruent CTs (his sun vs. the sun) was compared to the processing of morphosyntactic and semantic violations in control conditions. Whereas the control conditions elicited classic electrophysiological violation responses (N400, LAN, & P600), CT-incongruences did not. Instead they showed novel concept-type specific response patterns. The absence of the classic ERP components suggests that CT-incongruent determination is not perceived as a violation of the semantic or morphosyntactic structure of the noun phrase.

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  • Nayernia, L., Van den Vijver, R., & Indefrey, P. (2019). The influence of orthography on phonemic knowledge: An experimental investigation on German and Persian. Journal of Psycholinguistic Research, 48(6), 1391-1406. doi:10.1007/s10936-019-09664-9.

    Abstract

    This study investigated whether the phonological representation of a word is modulated by its orthographic representation in case of a mismatch between the two representations. Such a mismatch is found in Persian, where short vowels are represented phonemically but not orthographically. Persian adult literates, Persian adult illiterates, and German adult literates were presented with two auditory tasks, an AX-discrimination task and a reversal task. We assumed that if orthographic representations influence phonological representations, Persian literates should perform worse than Persian illiterates or German literates on items with short vowels in these tasks. The results of the discrimination tasks showed that Persian literates and illiterates as well as German literates were approximately equally competent in discriminating short vowels in Persian words and pseudowords. Persian literates did not well discriminate German words containing phonemes that differed only in vowel length. German literates performed relatively poorly in discriminating German homographic words that differed only in vowel length. Persian illiterates were unable to perform the reversal task in Persian. The results of the other two participant groups in the reversal task showed the predicted poorer performance of Persian literates on Persian items containing short vowels compared to items containing long vowels only. German literates did not show this effect in German. Our results suggest two distinct effects of orthography on phonemic representations: whereas the lack of orthographic representations seems to affect phonemic awareness, homography seems to affect the discriminability of phonemic representations.
  • Redmann, A., FitzPatrick, I., & Indefrey, P. (2019). The time course of colour congruency effects in picture naming. Acta Psychologica, 196, 96-108. doi:10.1016/j.actpsy.2019.04.005.

    Abstract

    In our interactions with people and objects in the world around us, as well as in communicating our thoughts, we rely on the use of conceptual knowledge stored in long-term memory. From a frame-theoretic point of view, a concept is represented by a central node and recursive attribute-value structures further specifying the concept. The present study explores whether and how the activation of an attribute within a frame might influence access to the concept's name in language production, focussing on the colour attribute. Colour has been shown to contribute to object recognition, naming, and memory retrieval, and there is evidence that colour plays a different role in naming objects that have a typical colour (high colour-diagnostic objects such as tomatoes) than in naming objects without a typical colour (low colour-diagnostic objects such as bicycles). We report two behavioural experiments designed to reveal potential effects of the activation of an object's typical colour on naming the object in a picture-word interference paradigm. This paradigm was used to investigate whether naming is facilitated when typical colours are presented alongside the to-be-named picture (e.g., the word “red” superimposed on the picture of a tomato), compared to atypical colours (such as “brown”), unrelated adjectives (such as “fast”), or random letter strings. To further explore the time course of these potential effects, the words were presented at different time points relative to the to-be-named picture (Exp. 1: −400 ms, Exp. 2: −200 ms, 0 ms, and+200 ms). By including both high and low colour-diagnostic objects, it was possible to explore whether the activation of a colour differentially affects naming of objects that have a strong association with a typical colour. The results showed that (pre-)activation of the appropriate colour attribute facilitated naming compared to an inappropriate colour. This was only the case for objects closely connected with a typical colour. Consequences of these findings for frame-theoretic accounts of conceptual representation are discussed.
  • Weber, K., Christiansen, M., Indefrey, P., & Hagoort, P. (2019). Primed from the start: Syntactic priming during the first days of language learning. Language Learning, 69(1), 198-221. doi:10.1111/lang.12327.

    Abstract

    New linguistic information must be integrated into our existing language system. Using a novel experimental task that incorporates a syntactic priming paradigm into artificial language learning, we investigated how new grammatical regularities and words are learned. This innovation allowed us to control the language input the learner received, while the syntactic priming paradigm provided insight into the nature of the underlying syntactic processing machinery. The results of the present study pointed to facilitatory syntactic processing effects within the first days of learning: Syntactic and lexical priming effects revealed participants’ sensitivity to both novel words and word orders. This suggested that novel syntactic structures and their meaning (form–function mapping) can be acquired rapidly through incidental learning. More generally, our study indicated similar mechanisms for learning and processing in both artificial and natural languages, with implications for the relationship between first and second language learning.
  • Niccolai, V., Klepp, A., Indefrey, P., Schnitzler, A., & Biermann-Ruben, K. (2017). Semantic discrimination impacts tDCS modulation of verb processing. Scientific Reports, 7: 17162. doi:10.1038/s41598-017-17326-w.

    Abstract

    Motor cortex activation observed during body-related verb processing hints at simulation accompanying linguistic understanding. By exploiting the up- and down-regulation that anodal and cathodal transcranial direct current stimulation (tDCS) exert on motor cortical excitability, we aimed at further characterizing the functional contribution of the motor system to linguistic processing. In a double-blind sham-controlled within-subjects design, online stimulation was applied to the left hemispheric hand-related motor cortex of 20 healthy subjects. A dual, double-dissociation task required participants to semantically discriminate concrete (hand/foot) from abstract verb primes as well as to respond with the hand or with the foot to verb-unrelated geometric targets. Analyses were conducted with linear mixed models. Semantic priming was confirmed by faster and more accurate reactions when the response effector was congruent with the verb’s body part. Cathodal stimulation induced faster responses for hand verb primes thus indicating a somatotopical distribution of cortical activation as induced by body-related verbs. Importantly, this effect depended on performance in semantic discrimination. The current results point to verb processing being selectively modifiable by neuromodulation and at the same time to a dependence of tDCS effects on enhanced simulation. We discuss putative mechanisms operating in this reciprocal dependence of neuromodulation and motor resonance.

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