Rules and heuristics during sentence comprehension: evidence from a dual-task brain potential study

The Automatic but Flexible and Content-Dependent Nature of Syntax

Syntactic processing has often been considered an utmost example of unconscious automatic processing. In this line, it has been demonstrated that masked words containing syntactic anomalies are processed by our brain triggering event related potential (ERP) components similar to the ones triggered by conscious syntactic anomalies, thus supporting the automatic nature of the syntactic processing. Conversely, recent evidence also points out that regardless of the level of awareness, emotional information and other relevant extralinguistic information modulate conscious syntactic processing too. These results are also in line with suggestions that, under certain circumstances, syntactic processing could also be flexible and context-dependent. However, the study of the concomitant automatic but flexible conception of syntactic parsing is very scarce. Hence, to this aim, we examined whether and how masked emotional words (positive, negative, and neutral masked adjectives) containing morphosyntactic anomalies (half of the cases) affect linguistic comprehension of an ongoing unmasked sentence that also can contain a number agreement anomaly between the noun and the verb. ERP components were observed to emotional information (EPN), masked anomalies (LAN and a weak P600), and unmasked ones (LAN/N400 and P600). Furthermore, interactions in the processing of conscious and unconscious morphosyntactic anomalies and between unconscious emotional information and conscious anomalies were detected. The findings support, on the one hand, the automatic nature of syntax, given that syntactic components LAN and P600 were observed to unconscious anomalies. On the other hand, the flexible, permeable, and context-dependent nature of the syntactic processing is also supported, since unconscious information modulated conscious syntactic components. This double nature of syntactic processing is in line with theories of automaticity, suggesting that even unconscious/automatic, syntactic processing is flexible, adaptable, and context-dependent.

Language comprehension in the social brain: Electrophysiological brain signals of social presence effects during syntactic and semantic sentence processing

Although, evolutionarily, language emerged predominantly for social purposes, much has yet to be uncovered regarding how language processing is affected by social context. Social presence research studies the ways in which the presence of a conspecific affects processing, but has yet to be thoroughly applied to language processes. The principal aim of this study was to see how syntactic and semantic language processing might be subject to mere social presence effects by studying Event-Related brain Potentials (ERP). In a sentence correctness task, participants read sentences with a semantic or syntactic anomaly while being either alone or in the mere presence of a confederate. Compared to the alone condition, the presence condition was associated with an enhanced N400 component and a more centro-posterior LAN component (interpreted as an N400). The results seem to imply a boosting of heuristic language processing strategies, proper of lexico-semantic operations, which actually entails a shift in the strategy to process morphosyntactic violations, typically based on algorithmic or rule-based strategies. The effects cannot be related to increased arousal levels. The apparent enhancement of the activity in the precuneus while in presence of another person suggests that the effects conceivably relate to social cognitive and attentional factors. The present results suggest that understanding language comprehension would not be complete without considering the impact of social presence effects, inherent to the most natural and fundamental communicative scenarios.

Effects of reader's facial expression on syntactic processing: A brain potential study

Embodied views of language support that facial sensorimotor information can modulate language comprehension. The aim of this study is to test whether the syntactic processing of simple sentences, as measured with event-related brain potentials (ERP), could be affected by reader's facial expressions. Participants performed a correctness decision task using sentences that could be either correct (50%) or contain a morphosyntactic disagreement (either in gender or number), while making one of four facial expressions: participants either (a) posed no facial expression ("control" condition) (b) brought their eyebrows together, making the ends of two golf tees touch ("frown" condition), (c) held a pencil with their teeth ("smile" condition), or (d) held the pencil using their lips ("non-smile" condition). In all conditions the customary left anterior negativities did not appear. In contrast, an N400-like component emerged, which was larger for the "frown" condition and reduced in the "smile" and "non-smile" conditions. These results can be interpreted as the consequence of either an unconscious emotion induction or an interplay between the motor and the language systems subsequent to the effort needed to hold the facial expression.

The nature of morphosyntactic processing during language perception. Evidence from an additional-task study in Spanish and German

The present study investigates in how far morphosyntactic processing is affected by an additional non-verbal task and whether this effect differs between German and Spanish, two languages with differences in processing grammatical gender (lexical vs. cue-based processing). By manipulating task load and language we aimed at getting an insight into subprocesses of morphosyntax and their dependence on resources of general and verbal working memory, respectively. In more general terms, this study contributes to the debate on the modularity of morphosyntax. Written German or Spanish sentences with or without gender violations were presented word by word to native speakers. The critical words temporally overlapped in different degrees with a non-linguistic stimulus (a high or low tone). In a single task (Experiment 1) participants judged sentence acceptability and ignored the tones. Experiment 2 required a response to the tones. Left-anterior negativity (LAN) and P600 components were analyzed in the ERPs to critical words. Whereas the LAN was not affected by any of the experimental manipulations, the P600 was modulated as a function of language during the single task conditions (Experiment 1). In Experiment 2 the additional task did not add up with this effect; instead, the differences between language groups vanished. This may indicate that the processes reflected in the P600 draw on resources of general working memory. The LAN data seem to be in line with modularity of first pass morphosyntactic processing, although this interpretation contradicts findings from other studies. The P600 results may highlight the flexibility of sentence-based syntactic processing.

Attentional modulation of orthographic neighborhood effects during reading: Evidence from event-related brain potentials in a psychological refractory period paradigm

It is often assumed that word reading proceeds automatically. Here, we tested this assumption by recording event-related potentials during a psychological refractory period (PRP) paradigm, requiring lexical decisions about written words. Specifically, we selected words differing in their orthographic neighborhood size-the number of words that can be obtained from a target by exchanging a single letter-and investigated how influences of this variable depend on the availability of central attention. As expected, when attentional resources for lexical decisions were unconstrained, words with many orthographic neighbors elicited larger N400 amplitudes than those with few neighbors. However, under conditions of high temporal overlap with a high priority primary task, the N400 effect was not statistically different from zero. This finding indicates strong attentional influences on processes sensitive to orthographic neighbors during word reading, providing novel evidence against the full automaticity of processes involved in word reading. Furthermore, in conjunction with the observation of an underadditive interaction between stimulus onset asynchrony (SOA) and orthographic neighborhood size in lexical decision performance, commonly taken to indicate automaticity, our results raise issues concerning the standard logic of cognitive slack in the PRP paradigm.

Isolating the Effects of Word's Emotional Valence on Subsequent Morphosyntactic Processing: An Event-Related Brain Potentials Study

Emotional information significantly affects cognitive processes, as proved by research in the past decades. Recently, emotional effects on language comprehension and, particularly, syntactic processing, have been reported. However, more research is needed, as this is yet very scarce. The present paper focuses on the effects of emotion-laden linguistic material (words) on subsequent morphosyntactic processing, by using Event-Related brain Potentials (ERP). The main aim of this paper is to clarify whether the effects previously reported remain when positive, negative and neutral stimuli are equated in arousal levels and whether they remain long-lasting. In addition, we aimed at testing whether these effects vary as a function of the task performed with the emotion-laden words, to assess their robustness across variations in attention and cognitive load during the processing of the emotional words. In this regard, two different tasks were performed: a reading aloud (RA) task, where participants simply read aloud the words, written in black on white background, and an Emotional Stroop (ES) task, where participants named the colors in which the emotional words were shown. After these words, neutral sentences followed, that had to be evaluated for grammaticality while recording ERPs (50% containing a morphosyntactic anomaly). ERP analyses showed main effects of valence across tasks on the two components reflecting morphosyntactic processing: The Left Anterior Negativity (LAN) is increased by previous emotional words (more by negative than positive) relative to neutral ones, while the P600 is similarly decreased. No interactions between task and valence were found. As a result, an emotion-laden word preceding a sentence can modulate the syntactic processing of the latter, independently of the arousal and processing conditions of the emotional word.

Subliminal Emotional Words Impact Syntactic Processing: Evidence from Performance and Event-Related Brain Potentials

Recent studies demonstrate that syntactic processing can be affected by emotional information and that subliminal emotional information can also affect cognitive processes. In this study, we explore whether unconscious emotional information may also impact syntactic processing. In an Event-Related brain Potential (ERP) study, positive, neutral and negative subliminal adjectives were inserted within neutral sentences, just before the presentation of the supraliminal adjective. They could either be correct (50%) or contain a morphosyntactic violation (number or gender disagreements). Larger error rates were observed for incorrect sentences than for correct ones, in contrast to most studies using supraliminal information. Strikingly, emotional adjectives affected the conscious syntactic processing of sentences containing morphosyntactic anomalies. The neutral condition elicited left anterior negativity (LAN) followed by a P600 component. However, a lack of anterior negativity and an early P600 onset for the negative condition were found, probably as a result of the negative subliminal correct adjective capturing early syntactic resources. Positive masked adjectives in turn prompted an N400 component in response to morphosyntactic violations, probably reflecting the induction of a heuristic processing mode involving access to lexico-semantic information to solve agreement anomalies. Our results add to recent evidence on the impact of emotional information on syntactic processing, while showing that this can occur even when the reader is unaware of the emotional stimuli.

Odor-induced mood state modulates language comprehension by affecting processing strategies

It is controversial whether mood affects cognition by triggering specific processing strategies or by limiting processing resources. The current event-related potential (ERP) study pursued this issue by examining how mood modulates the processing of task relevant/irrelevant information. In question-answer pairs, a question context marked a critical word in the answer sentence as focus (and thus relevant) or non-focus (thereby irrelevant). At the same time, participants were exposed to either a pleasant or unpleasant odor to elicit different mood states. Overall, we observed larger N400s when the critical words in the answer sentences were semantically incongruent (rather than congruent) with the question context. However, such N400 effect was only found for focused words accompanied by a pleasant odor and for both focused and non-focused words accompanied by an unpleasant odor, but not for non-focused words accompanied by a pleasant odor. These results indicate top-down attentional shift to the focused information in a positive mood state and non-selective attention allocated to the focused and non-focused information in a less positive mood state, lending support to the "processing strategy" hypothesis. By using a novel approach to induce mood states, our study provides fresh insights into the mechanisms underlying mood modulation of language comprehension.

P600 alteration of syntactic language processing in patients with bipolar mania: Comparison to schizophrenic patients and healthy subjects

BACKGROUND

Disturbances in thought, speech, and linguistic processing are frequently observed in bipolar manic patients, but the underlying neurophysiological mechanisms are not well understood. P600 is a distinct, positive event-related potential component elicited by syntactic violations. Using the P600 ERP, we examined neural processing of syntactic language comprehension in patients with bipolar mania compared to patients with schizophrenia and healthy people.

METHOD

P600s were recorded from 21 manic patients with bipolar disorder, 26 patients with schizophrenia, and 29 healthy subjects during the presentation of 120 auditory sentences with syntactic violations or non-violations. Subjects were asked to judge whether each sentence was correct or incorrect.

RESULTS

Patients with mania and schizophrenia had significantly smaller P600 amplitudes associated with syntactic violations compared with healthy subjects. There was no difference in P600 amplitude between patient groups. For behavioral performance, patients with schizophrenia had significantly less accurate rates and longer reaction times compared with healthy subjects, whereas manic patients exhibited no significant differences in accuracy and only showed increased reaction times in comparison with healthy subjects.

LIMITATIONS

Psychotropic drug usage and small sample size.

CONCLUSION

Patients with bipolar mania have reduced P600 amplitude, comparable to patients with schizophrenia. Our findings may represent the first neurophysiological evidence of abnormal syntactic linguistic processing in bipolar mania.

Is Semantic Processing During Sentence Reading Autonomous or Controlled? Evidence from the N400 Component in a Dual Task Paradigm

The present study contributes to the discussion on the automaticity of semantic processing. Whereas most previous research investigated semantic processing at word level, the present study addressed semantic processing during sentence reading. A dual task paradigm was combined with the recording of event-related brain potentials. Previous research at word level processing reported different patterns of interference with the N400 by additional tasks: attenuation of amplitude or delay of latency. In the present study, we presented Spanish sentences that were semantically correct or contained a semantic violation in a critical word. At different intervals preceding the critical word a tone was presented that required a high-priority choice response. At short intervals/high temporal overlap between the tasks mean amplitude of the N400 was reduced relative to long intervals/low temporal overlap, but there were no shifts of peak latency. We propose that processing at sentence level exerts a protective effect against the additional task. This is in accord with the attentional sensitization model (Kiefer & Martens, 2010), which suggests that semantic processing is an automatic process that can be enhanced by the currently activated task set. The present experimental sentences also induced a P600, which is taken as an index of integrative processing. Additional task effects are comparable to those in the N400 time window and are briefly discussed.

From incoherence to mirth: neuro-cognitive processing of garden-path jokes

In so-called garden-path jokes, an initial semantic representation is violated, and semantic revision reestablishes a coherent representation. 48 jokes were manipulated in three conditions: (i) a coherent ending, (ii) a joke ending, and (iii) a discourse-incoherent ending. A reading times study (N = 24) and three studies with recordings of ERP and pupil changes (N = 21, 24, and 24, respectively) supported the hypothesized cognitive processes. Jokes showed increased reading times of the final word compared to coherent endings. ERP data mainly indicated semantic integration difficulties (N400). Larger pupil diameters to joke endings presumably reflect emotional responses. ERP evidence for increased discourse processing efforts and emotional responses, as assumed to be reflected in modulations of the late left anterior negativity (LLAN) and in an enhanced late frontal positivity (fP600), respectively, remains however incomplete. Processing of incoherent endings was also accompanied by increased reading times, a stronger and sustained N400, and context-sensitive P600 effects. Together, these findings provide evidence for a sequential, non-monotonic, and incremental discourse comprehension of garden-path jokes.

Differential task effects on N400 and P600 elicited by semantic and syntactic violations

Syntactic violations in sentences elicit a P600 component in the event-related potential, which is frequently interpreted as signaling reanalysis or repair of the sentence structure. However, P600 components have been reported also for semantic and combined semantic and syntactic violations, giving rise to still other interpretations. In many of these studies, the violation might be of special significance for the task of the participants; however there is a lack of studies directly targeting task effects on the P600. Here we repeated a previously published study but using a probe verification task, focusing on individual words rather than on sentence correctness and directly compared the results with the previous ones. Although a (somewhat smaller) N400 component occurred also in the present study, we did not observe a parietal P600 component. Instead, we found a late anterior negativity. Possibly, the parietal P600 observed in sentence acceptability paradigms relates to the target value of the violations or to late sentence structure-specific processes that are more task-sensitive than the N400 and which are or not initiated in the probe verification task. In any case the present findings show a strong dependency of P600-eliciting processes from attention to the sentences context whereas the N400 eliciting processes appear relatively robust.

The influence of emotional words on sentence processing: electrophysiological and behavioral evidence

Whereas most previous studies on emotion in language have focussed on single words, we investigated the influence of the emotional valence of a word on the syntactic and semantic processes unfolding during sentence comprehension, by means of event-related brain potentials (ERP). Experiment 1 assessed how positive, negative, and neutral adjectives that could be either syntactically correct or incorrect (violation of number agreement) modulate syntax-sensitive ERP components. The amplitude of the left anterior negativity (LAN) to morphosyntactic violations increased in negative and decreased in positive words in comparison to neutral words. In Experiment 2, the same sentences were presented but positive, negative, and neutral adjectives could be either semantically correct or anomalous given the sentence context. The N400 to semantic anomalies was not significantly affected by the valence of the violating word. However, positive words in a sentence seemed to influence semantic correctness decisions, also triggering an apparent N400 reduction irrespective of the correctness value of the word. Later linguistic processes, as reflected in the P600 component, were unaffected in either experiment. Overall, our results indicate that emotional valence in a word impacts the syntactic and semantic processing of sentences, with differential effects as a function of valence and domain.

How the emotional content of discourse affects language comprehension

Emotion effects on cognition have often been reported. However, only few studies investigated emotional effects on subsequent language processing, and in most cases these effects were induced by non-linguistic stimuli such as films, faces, or pictures. Here, we investigated how a paragraph of positive, negative, or neutral emotional valence affects the processing of a subsequent emotionally neutral sentence, which contained either semantic, syntactic, or no violation, respectively, by means of event-related brain potentials (ERPs). Behavioral data revealed strong effects of emotion; error rates and reaction times increased significantly in sentences preceded by a positive paragraph relative to negative and neutral ones. In ERPs, the N400 to semantic violations was not affected by emotion. In the syntactic experiment, however, clear emotion effects were observed on ERPs. The left anterior negativity (LAN) to syntactic violations, which was not visible in the neutral condition, was present in the negative and positive conditions. This is interpreted as reflecting modulatory effects of prior emotions on syntactic processing, which is discussed in the light of three alternative or complementary explanations based on emotion-induced cognitive styles, working memory, and arousal models. The present effects of emotion on the LAN are especially remarkable considering that syntactic processing has often been regarded as encapsulated and autonomous.

How is sentence processing affected by external semantic and syntactic information? Evidence from event-related potentials

Background

A crucial question for understanding sentence comprehension is the openness of syntactic and semantic processes for other sources of information. Using event-related potentials in a dual task paradigm, we had previously found that sentence processing takes into consideration task relevant sentence-external semantic but not syntactic information. In that study, internal and external information both varied within the same linguistic domain—either semantic or syntactic. Here we investigated whether across-domain sentence-external information would impact within-sentence processing.

Methodology

In one condition, adjectives within visually presented sentences of the structure [Det]-[Noun]-[Adjective]-[Verb] were semantically correct or incorrect. Simultaneously with the noun, auditory adjectives were presented that morphosyntactically matched or mismatched the visual adjectives with respect to gender.

Findings

As expected, semantic violations within the sentence elicited N400 and P600 components in the ERP. However, these components were not modulated by syntactic matching of the sentence-external auditory adjective. In a second condition, syntactic within-sentence correctness-variations were combined with semantic matching variations between the auditory and the visual adjective. Here, syntactic within-sentence violations elicited a LAN and a P600 that did not interact with semantic matching of the auditory adjective. However, semantic mismatching of the latter elicited a frontocentral positivity, presumably related to an increase in discourse level complexity.

Conclusion

The current findings underscore the open versus algorithmic nature of semantic and syntactic processing, respectively, during sentence comprehension.