Conditionals in context: Brain signatures of prediction in discourse processing

Comprehenders are known to generate expectations about upcoming linguistic input at the sentence and discourse level. However, most previous studies on prediction focused mainly on word-induced brain activity rather than examining neural activity preceding a critical stimulus in discourse processing, where prediction actually takes place. In this EEG study, participants were presented with multiple sentences resembling a discourse including conditional sentences with either only if or if, which are characterized by different semantics, triggering stronger or weaker predictions about the possible continuation of the presented discourses, respectively. Results revealed that discourses including only if, as compared to discourses with bare if, triggered an increased predictive neural activity before the expected critical word, resembling the readiness potential. Moreover, word-induced P300 brain responses were found to be enhanced by unpredictable discourse continuations and reduced in predictable discourse continuations. Intriguingly, brain responses preceding and following the critical word were found to be correlated, which yields evidence for predictive activity modulating word-induced processing on the discourse level. These findings shed light on the predictive nature of neural processes at the discourse level, critically advancing our understanding of the functional interconnection between discourse understanding and prediction processes in brain and mind.

Text validation: Overlooking consistency effect discrepancies

The consistency effect, prevalent in the text comprehension literature, comprises longer reading times for inconsistent than equivalent consistent text continuations. It is widely interpreted as reflecting readers' effective "validation" of text coherence. However, there are also numerous phenomena of readers' deficient validation, sometimes collectively labelled "misinformation effects." This study asked whether readers become consciously aware of the text discrepancies diagnosed by the consistency effect. Experiment 1 scrutinized (a) conspicuous conceptual inconsistencies and (b) character-trait inconsistencies. It replicated the consistency effect both at a critical target sentence and at a subsequent sentence (spillover). Experiment 2 replaced self-paced reading with consistency judgments about the target sentences. The subjects overlooked almost half of the inconsistencies, thus denying that readers reliably become aware of consistency-effect discrepancies. In Experiment 3, the former target sentences were reframed as explicit questions. Accuracy for inconsistencies was statistically indistinguishable from accuracy for consistent targets, favoring the interpretation that Experiment 2 subjects overlooked known, encoded discrepancies. The results are interpreted with reference to Kintsch's (Psychological Review, 95, 163-182, Kintsch, 1988; Comprehension. New York: Cambridge University Press, Kintsch, 1998) construction-integration model, a refinement of which adds an immediate, passive stage of validation processing to construction and integration. It is proposed that passive validation affords the detection of text inconsistencies that do not reach the level of readers' conscious awareness.

Negation Cancels Discourse-Level Processing Differences: Evidence from Reading Times in Concession and Result Relations

Seminal studies on negation revealed that negative sentences are difficult to process, as they require an extra mental step. Similarly, at the discourse level, concession has been repeatedly shown to be more complex than other relations such as result because it implies the denial of an inference. The affinity between negation and concession prompted the present study to test whether overt verb polarity would affect the processing of upcoming discourse relations. In particular, it investigated whether negation can act as a cue to help process concessive relations. Results from four self-paced reading experiments indeed show a robust facilitation effect of negation on concession that cancels the baseline difference between concessive and result relations, thus nuancing existing context-blind categorizations of concession as a highly complex relation. This study furthers our understanding of how various types of cues interact in discourse processing and switches the focus from "what makes negation easier to process" to "what is made easier thanks to negation".

Mental Simulations of Phonological Representations Are Causally Linked to Silent Reading of Direct Versus Indirect Speech

Embodied theories propose that language is understood via mental simulations of sensory states related to perception and action. Given that direct speech (e.g., She says, "It's a lovely day!") is perceived to be more vivid than indirect speech (e.g., She says (that) it's a lovely day) in perception, recent research shows in silent reading that more vivid speech representations are mentally simulated for direct speech than for indirect speech. This 'simulated' speech is found to contain suprasegmental prosodic representations (e.g., speech prosody) but its phonological detail and its causal role in silent reading of direct speech remain unclear. Here in three experiments, I explored the phonological aspect and the causal role of speech simulations in silent reading of tongue twisters in direct speech, indirect speech and non-speech sentences. The results demonstrated greater visual tongue-twister effects (phonemic interference) during silent reading (Experiment 1) but not oral reading (Experiment 2) of direct speech as compared to indirect speech and non-speech. The tongue-twister effects in silent reading of direct speech were selectively disrupted by phonological interference (concurrent articulation) as compared to manual interference (finger tapping) (Experiment 3). The results replicated more vivid speech simulations in silent reading of direct speech, and additionally extended them to the phonological dimension. Crucially, they demonstrated a causal role of phonological simulations in silent reading of direct speech, at least in tongue-twister reading. The findings are discussed in relation to multidimensionality and task dependence of mental simulation and its mechanisms.

Examining the factors that affect structural repetition in question answering

We present two experiments that examine structural priming in the single-trial phone-call paradigm introduced by Levelt and Kelter (Cognitive psychology, 14 (1), 78-106, 1982). Experimenters called businesses and asked either What time do you close? or At what time do you close? Participants were more likely to produce a prepositional response (At 7 o'clock vs. 7 o'clock) following a prepositional question than following a non-prepositional question. Experiments 1 and 2 attempted to strengthen the priming effect by having the experimenters engage in a brief interaction with the participant before asking the What time…? question. The interactions did not reliably affect the observed priming effect. An analysis across experiments demonstrated that the priming effect found in this paradigm is generally smaller than the average structural priming effect (as reported in Mahowald, James, Futrell, & Gibson, Journal of Memory and Language, 91, 5-27, 2016), but within the range of the effects that are observed in different structural priming paradigms.

The neurocognitive signature of focus alternatives

Focus alternatives are words/phrases that can substitute for the focused constituent of an utterance. In "Carsten has picked [CHERRIES]_F from the tree.", (marked by pitch focus on cherries), the speaker wants to not only convey the fact that Carsten has picked cherries, but also to contrast cherries with other fruit that could have been picked, such as plums. Although focus alternatives are key to understanding the implicit aspects of an utterance, nothing is known about their neural representation. We directly contrasted neural representations of lexico-semantic similarity and focus alternative status using fMRI. Semantic relatedness was reflected in decreased activation in the bilateral superior temporal gyri. By contrast, processing of focus alternatives induced increased activations in the precuneus and the fronto-median wall, two regions previously implicated in discourse processing. These results suggest that focus alternative status is processed separately from semantic relatedness, at the level of discourse integration.

Tracking and maintenance of goal-relevant location information in narratives

Two experiments were conducted to examine whether readers maintain location in a highly-accessible state in memory during narrative comprehension while reading narratives with goals closely tied to locations that story protagonists needed to reach. College undergraduates (n = 185, n = 100) read short, experiment-generated narratives manipulated in three ways. First, protagonist location was manipulated such that the goal was either completed or not, making subsequent critical sentences consistent or inconsistent, respectively, with the last-described location. Second, text distance between the manipulation of location and the later target sentence was varied such that the critical sentences were close to or distant from the last mention of location. Third, location words that explicitly mentioned the protagonist's location were either present or not in the critical sentences. Readers took longer to read critical sentences when the protagonist had not been described as reaching the goal location, suggesting that readers were maintaining location information in highly-accessible state. This effect emerged with or without explicit location words in the critical sentences and with near or distant backgrounding. These results are discussed in the context of scenario-based and memory-based theories of comprehension.

1/f neural noise and electrophysiological indices of contextual prediction in aging

Prediction of upcoming words during reading has been suggested to enhance the efficiency of discourse processing. Emerging models have postulated that predictive mechanisms require synchronous firing of neural networks, but to date, this relationship has been investigated primarily through oscillatory activity in narrow frequency bands. A recently-developed measure proposed to reflect broadband neural activity - and thereby synchronous neuronal firing - is 1/f neural noise extracted from EEG spectral power. Previous research has indicated that this measure of 1/f neural noise changes across the lifespan, and these neural changes predict age-related behavioral impairments in visual working memory. Using a cross-sectional sample of young and older adults, we examined age-related changes in 1/f neural noise and whether this measure predicted ERP correlates of successful lexical prediction during discourse comprehension. 1/f neural noise across two different language tasks revealed high within-subject correlations, indicating that this measure can provide a reliable index of individualized patterns of neural activation. In addition to age, 1/f noise was a significant predictor of N400 effects of successful lexical prediction; however, noise did not mediate age-related declines in other ERP effects. We discuss broader implications of these findings for theories of predictive processing, as well as potential applications of 1/f noise across research populations.

Suppression and Working Memory in Auditory Comprehension of L2 Narratives: Evidence from Cross-Modal Priming

Using a cross-modal priming task, the present study explores whether Chinese-English bilinguals process goal related information during auditory comprehension of English narratives like native speakers. Results indicate that English native speakers adopted both mechanisms of suppression and enhancement to modulate the activation of goals and keep track of the "causal path" in narrative events and that L1 speakers with higher working memory (WM) capacity are more skilled at attenuating interference. L2 speakers, however, experienced the phenomenon of "facilitation-without-inhibition." Their difficulty in suppressing irrelevant information was related to their performance in the test of working memory capacity. For the L2 group with greater working memory capacity, the effects of both enhancement and suppression were found. These findings are discussed in light of a landscape model of L2 text comprehension which highlights the need for WM to be incorporated into comprehensive models of L2 processing as well as theories of SLA.

Do discourse global coherence and cumulated information impact on sentence syntactic processing? An event-related brain potentials study

The present study aimed at exploring how two main primarily semantic factors of discourse comprehension, namely global coherence and amount of information cumulated across a passage, may impact on the sentential syntactic processing. This was measured in two event-related brain potentials (ERP) to grammatical (morphosyntactic) violations: anterior negativities (LAN) and posterior positivities (P600). Global coherence did not yield any significant effects on either ERP component, although it appeared advantageous to the detection of morphosyntactic errors. Anterior negativities were also unaffected by the amount of cumulated information. Accordingly, it seems that first-pass syntactic processes are unaffected by these discourse variables. In contrast, the first portion of the P600 was significantly modulated (increased) by the latter factor. This probably reflects bigger efforts to combine sentential information during situations highly demanding for working memory. Our results would suggest that processes involved in global discourse coherence appear relatively independent of the on-line syntactic and combinatorial mechanisms reflected in the LAN and the P600 components of the ERPs.

Reversing expectations during discourse comprehension

In two ERP experiments, we asked whether comprehenders used the concessive connective, even so, to predict upcoming events. Participants read coherent and incoherent scenarios, with and without even so, e.g. "Elizabeth had a history exam on Monday. She took the test and aced/failed it. (Even so), she went home and celebrated wildly.", as they rated coherence (Experiment 1) or simply answered intermittent comprehension questions (Experiment 2). The semantic function of even so was used to reverse real-world knowledge predictions, leading to an attenuated N400 to coherent versus incoherent target words ("celebrated"). Moreover, its pragmatic communicative function enhanced predictive processing, leading to more N400 attenuation to coherent targets in scenarios with than without even so. This benefit however, did not come for free: the detection of failed event predictions triggered a later posterior positivity and/or an anterior negativity effect, and costs of maintaining alternative likelihood relations manifest as a sustained negativity effect on sentence-final words.

Context-driven expectations about focus alternatives

What is conveyed by a sentence frequently depends not only on the descriptive content carried by its words, but also on implicit alternatives determined by the context of use. Four visual world eye-tracking experiments examined how alternatives are generated based on aspects of the discourse context and used in interpreting sentences containing the focus operators only and also. Experiment 1 builds on previous reading time studies showing that the interpretations of only sentences are constrained by alternatives explicitly mentioned in the preceding discourse, providing fine-grained time course information about the expectations triggered by only. Experiments 2 and 3 show that, in the absence of explicitly mentioned alternatives, lexical and situation-based categories evoked by the context are possible sources of alternatives. While Experiments 1-3 all demonstrate the discourse dependence of alternatives, only explicit mention triggered expectations about alternatives that were specific to sentences with only. By comparing only with also, Experiment 4 begins to disentangle expectations linked to the meanings of specific operators from those generalizable to the class of focus-sensitive operators. Together, these findings show that the interpretation of sentences with focus operators draws on both dedicated mechanisms for introducing alternatives into the discourse context and general mechanisms associated with discourse processing.

The neural representation of plural discourse entities

Little is known about the underlying neural structures that mediate the generation and tracking of discourse referents. In two functional magnetic resonance imaging experiments, we examined the neural structures involved in generating and maintaining the representations of multiple referents. Experiment 1 used two-sentence discourses with singular and plural conditions linking back to single or conjoined subjects. In Experiment 2, conjunction type was manipulated in order to keep the number of discourse entities constant across the discourse. Both experiments found greater activation in the superior parietal lobule bilaterally for plural entities relative to singular entities in Experiment 1 and for unconjoined plural entities relative to conjoined plural entities in Experiment 2. This parietal activation suggests that referring to multiple entities evokes multiple representations that need to be integrated and tracked. We discuss these findings in terms of psycholinguistic theories of multiple referent representations.

The fox and the cabra: an ERP analysis of reading code switched nouns and verbs in bilingual short stories

Comprehending a language (or code) switch within a sentence context triggers 2 electrophysiological signatures: an early left anterior negativity post code switch onset - a LAN - followed by a Late Positive Component (LPC). Word class and word position modulate lexico-semantic processes in the monolingual brain, e.g., larger N400 amplitude for nouns than verbs and for earlier than later words in the sentence. Here we test whether the bilingual brain is affected by word class and word position when code switching, or if the cost of switching overrides these lexico-semantic and sentence context factors. Adult bilinguals read short stories in English containing 8 target words. Targets were nouns or verbs, occurred early or late in a story and were presented alternately in English (non-switch) or Spanish (switch) across different story versions. Overall, switched words elicited larger LAN and LPC amplitude than non-switched words. The N400 amplitude was larger for nouns than verbs, more focal for switches than non-switches, and for early than late nouns but not for early than late verbs. Moreover, an early LPC effect was observed only for switched nouns, but not verbs. Together, this indicates that referential elements (nouns) may be harder to process and integrate than relational elements (verbs) in discourse, and when switched, nouns incur higher integration cost. Word position did not modulate the code switching effects, implying that switching between languages may invoke discourse independent processes.