Semantic Context Effects Research Articles

Examining the N400 semantic context effect item-by-item: Relationship to corpus-based measures of word co-occurrence

With increasing availability of digital text, there has been an explosion of computational methods designed to turn patterns of word co-occurrence in large text corpora into numerical scores expressing the “semantic distance” between any two words. The success of such methods is typically evaluated by how well they predict human judgments of similarity. Here, I examine how well corpus-based methods predict amplitude of the N400 component of the event-related potential (ERP), an online measure of lexical processing in brain electrical activity. ERPs elicited by the second words of 303 word pairs were analyzed at the level of individual items. Three corpus-based measures (mutual information, distributional similarity, and latent semantic analysis) were compared to a traditional measure of free association strength. In a regression analysis, corpus-based and free association measures each explained some of the variance in N400 amplitude, suggesting that these may tap distinct aspects of word relationships. Lexical factors of concreteness of word meaning, word frequency, number of semantic associates, and orthographic similarity also explained variance in N400 amplitude at the single-item level.

Lexical Retrieval is not by Competition: Evidence from the Blocked Naming Paradigm.

A central issue in research on speech production is whether or not the retrieval of words from the mental lexicon is a competitive process. An important experimental paradigm to study the dynamics of lexical retrieval is the blocked naming paradigm, in which participants name pictures of objects that are grouped by semantic category ('homogenous' or 'related' blocks) or not grouped by semantic category ('heterogeneous' or 'unrelated' blocks). Typically, pictures are repeated multiple times (or cycles) within both related and unrelated blocks. It is known that participants are slower in related than in unrelated blocks when the data are collapsed over all within-block repetitions. This semantic interference effect, as observed in the blocked naming task, is the strongest empirical evidence for the hypothesis of lexical selection by competition. Here we show, contrary to the accepted view, that the default polarity of semantic context effects in the blocked naming paradigm is facilitation, rather than interference. In a series of experiments we find that interference arises only when items repeat within a block, and only because of that repetition: What looks to be 'semantic interference' in the blocked naming paradigm is actually less repetition priming in related compared to unrelated blocks. These data undermine the theory of lexical selection by competition and indicate a model in which the most highly activated word is retrieved, regardless of the activation levels of nontarget words. We conclude that the theory of lexical selection by competition, and by extension the important psycholinguistic models based on that assumption, are no longer viable, and frame a new way to approach the question of how words are retrieved in spoken language production.

Prospective and retrospective semantic processing: Prediction, time, and relationship strength in event-related potentials

Semantic context effects have variously been attributed to prospective processing – predictions about upcoming words – or to retrospective appreciation of relationships after reading both context and target. In two experiments, we altered the core variable distinguishing prospective from retrospective processing, namely time. Word pairs varying in strength of relationship were presented sequentially, to allow time for anticipation of the second word, or simultaneously. For both sorts of presentation, the amplitude of the N400 component of the event-related potential was graded from Unrelated to Moderate/Weak to Strong associates. Strong associates showed a temporal advantage over weaker associates – an earlier context effect – only during sequential presentation. Spatial distributions of the N400 context effects also differed for simultaneous versus sequential presentation.

Effects of sentence context on phonemic categorization of natural and synthetic consonant-vowel tokens.

The purpose was to assess if phonemic categorization in sentential context is best explained by autonomous feedforward processing or by top-down feedback processing that affects phonemic representation. 11 listeners with normal hearing, ages 20-50 years, were asked to label consonants in /pi/-/ti/ consonant-vowel (CV) stimuli in 9-step continua. One continuum was derived from natural tokens and the other was synthetically generated. The CV stimuli were presented in isolation and in three sentential contexts: a neutral context, a context favoring /p/, and a context favoring /t/. For both natural and synthetic stimuli, the isolated and neutral context sentences yielded significantly more /t/ responses than sentence contexts primed for either /p/ or /t/. No other conditions were significantly different. Results did not show easily explainable semantic context effects. Instead, data clustering was more readily explained by top-down feedback processing affecting phonemic representation.

Mapping concrete and abstract meanings to new words using verbal contexts

In three experiments, we examine the effects of semantic context and word concreteness on the mapping of existing meanings to new words. We developed a new-word-learning paradigm in which participants were required to discover the meaning of a new-word form from a specific verbal context. The stimulus materials were manipulated according to word concreteness, context availability and semantic congruency across contexts. Overall, participants successfully learned the meaning of the new word whether it was a concrete or an abstract word. Concrete word meanings were discovered and learned faster than abstract word meanings even when matched on context availability. The present results are discussed considering the various hypotheses that have been used to try to explain the ‘concreteness effect’. We conclude that the present investigation provides new evidence that the concreteness effect observed in learning is due to the different organization of abstract and concrete conceptual information in semantic memory.

A Paradigm for Investigating Executive Control Mechanisms in Word Retrieval in Language-Impaired and Neurotypical Speakers

A Paradigm for Investigating Executive Control Mechanisms in Word Retrieval in Language-Impaired and Neurotypical Speakers

Gradients versus dichotomies: How strength of semantic context influences event-related potentials and lexical decision times

In experiments devoted to word recognition and/or language comprehension, reaction time in the lexical decision task is perhaps the most commonly used behavioral dependent measure, and the amplitude of the N400 component of the event-related potential (ERP) is the most common neural measure. Both are sensitive to multiple factors, including frequency of usage, orthographic similarity to other words, concreteness of word meaning, and preceding semantic context. All of these factors vary continuously. Published results have shown that both lexical decision times and N400 amplitudes show graded responses to graded changes of word frequency and orthographic similarity, but a puzzling discrepancy in their responsivity to the strength of a semantic context has received little attention. In three experiments, we presented pairs of words varying in the strengths of their semantic relationships, as well as unrelated pairs. In all three experiments, N400 amplitudes showed a gradient from unrelated to weakly associated to strongly associated target words, whereas lexical decision times showed a binary division rather than a gradient across strengths of relationship. This pattern of results suggests that semantic context effects in lexical decision and ERP measures arise from fundamentally different processes.

The Effects of Semantic Context and the Type and Amount of Acoustic Distortion on Lexical Decision by Younger and Older Adults

In this study, the authors investigated how acoustic distortion affected younger and older adults' use of context in a lexical decision task. The authors measured lexical decision reaction times (RTs) when intact target words followed acoustically distorted sentence contexts. Contexts were semantically congruent, neutral, or incongruent. Younger adults (n = 216) were tested on three distortion types: low-pass filtering, time compression, and masking by multitalker babble, using two amounts of distortion selected to control for word recognition accuracy. Older adults (n = 108) were tested on two amounts of time compression and one low-pass filtering condition. For both age groups, there was robust facilitation by congruent contexts but minimal inhibition by incongruent contexts. Facilitation decreased as distortion increased. Older listeners had slower RTs than younger listeners, but this difference was smaller in congruent than in neutral or incongruent conditions. After controlling for word recognition accuracy, older listeners' RTs were slower in time-compressed than in low-pass filtering conditions, but younger listeners performed similarly in both conditions. These RT results highlight the interdependence between bottom-up sensory and top-down semantic processing. Consistent with previous findings based on accuracy measures, compared with younger adults, older adults were disproportionately slowed when speech was time compressed but more facilitated by congruent contexts.

Cumulative and Non-Cumulative Semantic Interference in Object Naming: Evidence from Blocked and Continuous Manipulations of Semantic Context

Experiments involving blocked and continuous manipulations of the semantic naming context demonstrate that, when speakers name several taxonomically related objects in close succession, they display persistent interference effects. A review of studies using the blocked paradigm shows that, unlike the continuous paradigm, it typically does not induce cumulative interference effects in healthy speakers. This contrasts with the simulation results obtained from a model of semantic context effects recently put forward by Oppenheim and colleagues [Oppenheim, G. M., Dell, G. S., & Schwartz, M. F. (2010). The dark side of incremental learning: A model of cumulative semantic interference during lexical access in speech production. Cognition, 114, 227--262], which generates cumulative effects in both paradigms. We propose that the effects are non-cumulative in the blocked paradigm, because it allows participants to bias top-down the levels of activation of lexical-semantic representations, thereby curtailing the accumulating interference. Indeed, prior research has shown that the interference effects in the blocked paradigm are exacerbated when participants carry out a concurrent digit-retention task, loading on working memory and reducing their capacity to exert a top-down bias. In Experiment 1, combining the continuous paradigm with a digit-retention task, we demonstrate that this does not exacerbate cumulative context effects, corroborating the selective role of working memory and the associated top-down biasing mechanism in the blocked paradigm. A review of neuropsychological and neuroimaging studies demonstrates that left inferior frontal regions may play a critical role in controlling semantic interference top-down. We discuss the implications of these findings for language production research and for models of lexical-semantic encoding.

The Influence of Semantic Context on the Perception of Spanish-Accented American English

In this article, the authors examine (a) the effect of semantic context on accentedness, comprehensibility, and intelligibility of Spanish-accented American English (AE) as judged by monolingual AE listeners and (b) the interaction of semantic context and accentedness on comprehensibility and intelligibility. Twenty adult native (L1) Spanish speakers proficient in AE and 4 L1 AE speakers (controls) read 48 statements consisting of true-false, semantically meaningful, and semantically anomalous sentences. Eighty monolingual AE listeners assessed accentedness, comprehensibility, and intelligibility of the statements. A significant main effect was found for semantic category on all 3 dependent variables. Accents were perceived to be stronger, and both comprehensibility and intelligibility were worse, in semantically anomalous contexts. Speaker data were grouped into strong, mid-level, and mild accents. The interaction between semantic category and accent was significant for both comprehensibility and intelligibility. The effect of semantic context was strongest for strong accents. Intelligibility was excellent for speakers with mid-level accents in true-false and semantically meaningful contexts, and it was excellent for mild accents in all contexts. Listeners access semantic information, in addition to phonetic and phonotactic features, in the perception of nonnative speech. Both accent level and semantic context are important in research on foreign-accented speech.

Long-lasting inhibitory semantic context effects on object naming are necessarily conceptually mediated: Implications for models of lexical-semantic encoding

Abstract When participants name several taxonomically related objects in close succession, they display persistent interference effects. Experimental manipulations of the semantic naming context have been used in two variants, a blocked and a continuous paradigm. Counterintuitively, results from previous studies suggest that the context effects induced by these paradigms arise at distinct levels of processing, namely at the lemma level (blocked paradigm), and at the interface of conceptual and lexical representations (continuous paradigm). In five experiments, both variants of the paradigm were assessed in object naming, semantic classification, word naming, and word-plus-determiner naming tasks. Experiments 1–3 show that participants display semantic context effects only in those tasks that mandatorily require conceptual processing (semantic classification, object naming). Experiment 4 fails to replicate the finding that, in the continuous paradigm, semantic context effects can transfer from object naming to word-plus-determiner naming but not vice versa, instead yielding no transfer in either direction. Experiment 5 demonstrates that the effects seen in semantic classification and object naming influence each other, suggesting that they are causally linked and that they both originate at the conceptual level. The implications of these findings for current accounts of lexical-semantic encoding in word production are discussed.

Semantic versus perceptual interactions in neural processing of speech-in-noise

Native listeners make use of higher-level, context-driven semantic and linguistic information during the perception of speech-in-noise. In a recent behavioral study, using a new paradigm that isolated the semantic level of speech by using words, we showed that this native-language benefit is at least partly driven by semantic context (Golestani et al., 2009). Here, we used the same paradigm in a functional magnetic resonance imaging (fMRI) experiment to study the neural bases of speech intelligibility, as well as to study the neural bases of this semantic context effect in the native language. A forced-choice recognition task on the first of two auditorily presented semantically related or unrelated words was employed, where the first, 'target' word was embedded in different noise levels. Results showed that activation in components of the brain language network, including Broca's area and the left posterior superior temporal sulcus, as well as brain regions known to be functionally related to attention and task difficulty, was modulated by stimulus intelligibility. In line with several previous studies examining the role of linguistic context in the intelligibility of degraded speech at the sentence level, we found that activation in the angular gyrus of the left inferior parietal cortex was modulated by the presence of semantic context, and further, that this modulation depended on the intelligibility of the speech stimuli. Our findings help to further elucidate neural mechanisms underlying the interaction of context-driven and signal-driven factors during the perception of degraded speech, and this specifically at the semantic level.

Effects of Semantic and Acoustic Context on Nonword Detection in Children With Hearing Loss

Children with hearing loss (HL) are known to have smaller receptive vocabularies than children with normal hearing (NH). This may be due, in part, of their reduced exposure to new words and their slower rate of word learning. A necessary prerequisite to lexical development is the detection of new words in conversation. The purpose of this study was to examine the effects of HL on children's ability to detect the presence of nonwords within sentences that varied in semantic and acoustic context. Twenty-nine children with NH and 16 children with HL between the ages of 7 and 13 years participated. The children listened to short sentences and reported the number of nonwords detected, ranging from zero to two nonwords, in each sentence. The structure of the sentences was either meaningful or nonsensical to the children to reveal the effects of semantic context. The effects of acoustic context were revealed by presenting the sentences in quiet, steady-state noise, and in multi-talker babble. Significant effects of age (older > younger), hearing (NH > HL), and listening condition (quiet > noise and babble) were observed. Also, nonword detection was better for semantically meaningful sentences than for nonsense sentences. Error analyses revealed that the children with NH tended to underestimate the number of nonwords in meaningful sentences but not in nonsense sentences. The children with HL, however, were more likely to underestimate the number of nonwords than were the children with NH for both meaningful and nonsense sentences. These error patterns were observed in each listening condition. Error patterns suggest that children with HL apply strong repair strategies during speech perception, which may limit their opportunities to learn new words.

Differential processing of thematic and categorical conceptual relations in spoken word production.

Studies of semantic context effects in spoken word production have typically distinguished between categorical (or taxonomic) and associative relations. However, associates tend to confound semantic features or morphological representations, such as whole-part relations and compounds (e.g., BOAT-anchor, BEE-hive). Using a picture-word interference paradigm and functional magnetic resonance imaging (fMRI), we manipulated categorical (COW-rat) and thematic (COW-pasture) TARGET-distractor relations in a balanced design, finding interference and facilitation effects on naming latencies, respectively, as well as differential patterns of brain activation compared with an unrelated distractor condition. While both types of distractor relation activated the middle portion of the left middle temporal gyrus (MTG) consistent with retrieval of conceptual or lexical representations, categorical relations involved additional activation of posterior left MTG, consistent with retrieval of a lexical cohort. Thematic relations involved additional activation of the left angular gyrus. These results converge with recent lesion evidence implicating the left inferior parietal lobe in processing thematic relations and may indicate a potential role for this region during spoken word production.

Examining the Facilitative Effect of Semantic Context on Sentence Reading in Aphasia using Eye-Tracking

Examining the Facilitative Effect of Semantic Context on Sentence Reading in Aphasia using Eye-Tracking

Behavioral and fMRI evidence that cognitive ability modulates the effect of semantic context on speech intelligibility

Text cues facilitate the perception of spoken sentences to which they are semantically related (Zekveld, Rudner, et al., 2011). In this study, semantically related and unrelated cues preceding sentences evoked more activation in middle temporal gyrus (MTG) and inferior frontal gyrus (IFG) than nonword cues, regardless of acoustic quality (speech in noise or speech in quiet). Larger verbal working memory (WM) capacity (reading span) was associated with greater intelligibility benefit obtained from related cues, with less speech-related activation in the left superior temporal gyrus and left anterior IFG, and with more activation in right medial frontal cortex for related versus unrelated cues. Better ability to comprehend masked text was associated with greater ability to disregard unrelated cues, and with more activation in left angular gyrus (AG). We conclude that individual differences in cognitive abilities are related to activation in a speech-sensitive network including left MTG, IFG and AG during cued speech perception.

Poster #161 THE CHARACTERISTICS OF REVERSAL RESPONSE INITIATION AND ASSOCIATIVE LEARNING OF REWARD APPROACH AND LOSS AVERSION IN SCHIZOPHRENIA

Mentalizing deficits are a core manifestation of schizophrenia spectrum disorders. They contribute to the social handicap associated with the pathology, leading to disruption in autonomy, professional achievement, and interpersonal relationships. However, the underlying mechanisms of these deficits remain poorly understood. The aim of the present study was to test the hypothesis that context processing deficits would be responsible for mentalizing difficulties in schizotypy (personality traits considered as attenuated manifestations of schizophrenic symptoms) by using an irony comprehension task. Irony processing is a mentalizing exercise that requires the ability to take into account the semantic context to understand the literal meaning of the utterance, and to integrate the pragmatic context to infer the speaker's intention. These two steps of processing can be indexed by the N400 and P600 components, respectively, of event-related brain potentials (ERPs). Forty participants were assigned to high or low schizotypy groups according to their Schizotypal Personality Questionnaire (SPQ) score, and ERPs were recorded while they read short stories ending with a literal, ironic, or incompatible statement. In the low-SPQ group, there was a significant N400 semantic context effect (literal targets elicited less negative N400 amplitudes compared to incompatible targets) followed by a P600 pragmatic context effect (ironic targets evoked greater positive P600 amplitudes than literal targets). In contrast, there was neither a N400 nor P600 effect in the high-SPQ group. These abnormalities were associated with high interpersonal SPQ factor scores. These results show a strong association between context processing, mentalizing abilities, and interpersonal functioning in schizophrenia spectrum.

Interactions between Senses: Updating on Neural Mechanisms and Behavioral Evidence

Interactions between Senses: Updating on Neural Mechanisms and Behavioral Evidence

Homophonic Context Effects when Naming Japanese Kanji: Evidence for Processing Costs?

The current study investigated the effects of phonologically related context pictures on the naming latencies of target words in Japanese and Chinese. Reading bare words in alphabetic languages has been shown to be rather immune to effects of context stimuli, even when these stimuli are presented in advance of the target word (e.g., Glaser & Düngelhoff, 1984 ; Roelofs, 2003 ). However, recently, semantic context effects of distractor pictures on the naming latencies of Japanese kanji (but not Chinese hànzì) words have been observed (Verdonschot, La Heij, & Schiller, 2010 ). In the present study, we further investigated this issue using phonologically related (i.e., homophonic) context pictures when naming target words in either Chinese or Japanese. We found that pronouncing bare nouns in Japanese is sensitive to phonologically related context pictures, whereas this is not the case in Chinese. The difference between these two languages is attributed to processing costs caused by multiple pronunciations for Japanese kanji.

Electrophysiological effects of semantic context in picture and word naming

Recent language production studies have started to use electrophysiological measures to investigate the time course of word selection processes. An important contribution with respect to this issue comes from studies that have relied on an effect of semantic context in the semantic blocking task. Here we used this task to further establish the empirical pattern associated with the effect of semantic context, and whether the effect arises during output processing. Electrophysiological and reaction time measures were co-registered while participants overtly named picture and word stimuli in the semantic blocking task. The results revealed inhibitory reaction time effects of semantic context for both words and pictures, and a corresponding electrophysiological effect that could not be interpreted in terms of output processes. These data suggest that the electrophysiological effect of semantic context in the semantic blocking task does not reflect output processes, and therefore undermine an interpretation of this effect in terms of word selection.