The Neural Time Course of Semantic Ambiguity Resolution in Speech Comprehension

Semantically ambiguous words challenge speech comprehension, particularly when listeners must select a less frequent (subordinate) meaning at disambiguation. Using combined magnetoencephalography (MEG) and EEG, we measured neural responses associated with distinct cognitive operations during semantic ambiguity resolution in spoken sentences: (i) initial activation and selection of meanings in response to an ambiguous word and (ii) sentence reinterpretation in response to subsequent disambiguation to a subordinate meaning. Ambiguous words elicited an increased neural response approximately 400–800 msec after their acoustic offset compared with unambiguous control words in left frontotemporal MEG sensors, corresponding to sources in bilateral frontotemporal brain regions. This response may reflect increased demands on processes by which multiple alternative meanings are activated and maintained until later selection. Disambiguating words heard after an ambiguous word were associated with marginally increased neural activity over bilateral temporal MEG sensors and a central cluster of EEG electrodes, which localized to similar bilateral frontal and left temporal regions. This later neural response may reflect effortful semantic integration or elicitation of prediction errors that guide reinterpretation of previously selected word meanings. Across participants, the amplitude of the ambiguity response showed a marginal positive correlation with comprehension scores, suggesting that sentence comprehension benefits from additional processing around the time of an ambiguous word. Better comprehenders may have increased availability of subordinate meanings, perhaps due to higher quality lexical representations and reflected in a positive correlation between vocabulary size and comprehension success.

The relationship between sentence comprehension and lexical-semantic retuning

A single encounter with an ambiguous word (e.g. bark, ball) in the context of a less-frequent meaning (e.g. “Sally worried about how crowded the ball would be.”) can shift the later interpretation of the word toward the same subordinate meaning. This lexical-semantic retuning functions to improve future comprehension of ambiguous words. The present paper investigates the relationship between this form of learning and the specific processes that occur during sentence comprehension. One possibility is that lexical-semantic retuning occurs immediately upon hearing the ambiguous word, during initial meaning activation and selection, so priming should be strongest when the disambiguating context is provided before the ambiguous word (prior disambiguation). Alternatively, priming may relate to the degree of reinterpretation needed, which would predict maximal learning when the word is initially misunderstood because the critical context is given after the word (subsequent disambiguation, e.g. “Sally worried that the ball would be too crowded.”). In four experiments, adults listened to prior and subsequent disambiguation sentences, and were later tested on their interpretations of primed and unprimed ambiguous words. The results showed that lexical-semantic retuning can occur for both sentence types. Importantly, however, the emergence of priming for subsequent disambiguation sentences was sensitive to the prime conditions: when the task could potentially be performed without needing to re-analyse the ambiguity, then no significant priming was observed. This is consistent with the ‘good enough’ view of language processing which states that representations can remain as (im)precise as mandated by the situation, and that lexical-semantic retuning operates on the output of good-enough interpretation. More generally, our findings suggest that lexical-semantic retuning is driven by participants’ final interpretation of the word meanings during the prime encounter, regardless of initial meaning activation or misinterpretation.

Still Suspicious: The Suspicious-Coincidence Effect Revisited

Imagine hearing someone call a particular dalmatian a “dax.” The meaning of the novel noun dax is ambiguous between the subordinate meaning (dalmatian) and the basic-level meaning (dog). Yet both children and adults successfully learn noun meanings at the intended level of abstraction from similar evidence. Xu and Tenenbaum (2007a) provided an explanation for this apparent puzzle: Learners assume that examples are sampled from the true underlying category (strong sampling), making cases in which there are more observed exemplars more consistent with a subordinate meaning than cases in which there are fewer exemplars (the suspicious-coincidence effect). Authors of more recent work (Spencer, Perone, Smith, & Samuelson, 2011) have questioned the relevance of this finding, however, arguing that the effect occurs only when the examples are presented to the learner simultaneously. Across a series of 12 experiments ( N = 600), we systematically manipulated several experimental parameters that varied across previous studies, and we successfully replicated the findings of both sets of authors. Taken together, our data suggest that the suspicious-coincidence effect in fact is robust to presentation timing of examples but is sensitive to another factor that varied in the Spencer et al. (2011) experiments, namely, trial order. Our work highlights the influence of pragmatics on behavior in experimental tasks.

Contextual priming of word meanings is stabilized over sleep

Evidence is growing for the involvement of consolidation processes in the learning and retention of language, largely based on instances of new linguistic components (e.g., new words). Here, we assessed whether consolidation effects extend to the semantic processing of highly familiar words. The experiments were based on the word-meaning priming paradigm in which a homophone is encountered in a context that biases interpretation towards the subordinate meaning. The homophone is subsequently used in a word-association test to determine whether the priming encounter facilitates the retrieval of the primed meaning. In Experiment 1 (N = 74), we tested the resilience of priming over periods of 2 and 12 hours that were spent awake or asleep, and found that sleep periods were associated with stronger subsequent priming effects. In Experiment 2 (N = 55) we tested whether the sleep benefit could be explained in terms of a lack of retroactive interference by testing participants 24 hours after priming. Participants who had the priming encounter in the evening showed stronger priming effects after 24 hours than participants primed in the morning, suggesting that sleep makes priming resistant to interference during the following day awake. The results suggest that consolidation effects can be found even for highly familiar linguistic materials. We interpret these findings in terms of a contextual binding account in which all language perception provides a learning opportunity, with sleep and consolidation contributing to the updating of our expectations, ready for the next day.

Listeners and Readers Generalise Their Experience With Word Meanings Across Modalities

Research has shown that adults’ lexical-semantic representations are surprisingly malleable. For instance, the interpretation of ambiguous words (e.g. bark) is influenced by experience such that recently encountered meanings become more readily available (Rodd et al., 2016, 2013). However the mechanism underlying this word-meaning priming effect remains unclear, and competing accounts make different predictions about the extent to which information about word meanings that is gained within one modality (e.g. speech) is transferred to the other modality (e.g. reading) to aid comprehension. In two web-based experiments, ambiguous target words were primed with either written or spoken sentences that biased their interpretation toward a subordinate meaning, or were unprimed. About 20 minutes after the prime exposure, interpretation of these target words was tested by presenting them in either written or spoken form, using word association (Experiment 1, N=78) and speeded semantic relatedness decisions (Experiment 2, N=181). Both experiments replicated the auditory unimodal priming effect shown previously (Rodd et al., 2016, 2013) and revealed significant cross-modal priming: primed meanings were retrieved more frequently and swiftly across all primed conditions compared to the unprimed baseline. Furthermore, there were no reliable differences in priming levels between unimodal and cross-modal prime-test conditions. These results indicate that recent experience with ambiguous word meanings can bias the reader’s or listener’s later interpretation of these words in a modality-general way. We identify possible loci of this effect within the context of models of long-term priming and ambiguity resolution.

The processing of Chinese compound words with ambiguous morphemes in sentence context

We employed a boundary paradigm to investigate how Chinese two-character compounds (i.e., compound words) are processed during reading. The first character of the compound was an ambiguous morpheme that had a dominant and subordinate meaning. In Experiment 1, there were three previews of the second character: identical to the target character; the preview provided subordinate biasing information (the subordinate condition); the preview provided dominant biasing information (the dominant condition). An invisible boundary was inserted between the two characters. We found that gaze durations and go-past times on the compounds were longer in the subordinate condition than those in the dominant or identical conditions. In Experiment 2, the semantic similarity between target and preview words in the dominant condition was manipulated to determine whether the differences in fixation durations in Experiment 1 resulted from the semantic similarity between the preview and target words. There were significant fixation duration differences on the target word between the dominant and subordinate conditions only when the preview and target words were semantically related. This finding indicated that the whole-word meaning plays an important role in processing Chinese compounds and that the whole-word access route is the principal processing route in reading two-character compounds in Chinese.

The Fifth Slovene Hamlet: Return to Tradition?

Over the nearly two centuries that Hamlet has been a fixture of the Slovene cultural firmament, the complete text has been translated five times, mostly by highly esteemed figures of Slovene literature and literary translation. This article focuses on the most recent translation, which was done by the prominent Slovene drama translator Srečko Fišer for a performance at the National Theatre in Ljubljana in 2013. It examines the new translation’s relations to its source text as well as to the previous translations. After the late twentieth century, when Hamlet was regarded as a text to be challenged, this new translation indicates the return to the tradition of reverence both for the source text and its author, and for the older translations. This is demonstrated on all levels, from the choice of source text edition, which seems to bear more similarities with the older translations than with the most recent predecessors, to the style, which echoes the solutions used by the earlier translators. Fišer continues the Slovenian tradition to a far greater extent than the two translators twenty years ago, by using the same strategies as the early translators, not fixing what was not broken, and only adding his own interpretation to the existing ones, instead of challenging or ignoring them. At the same time, however, traces of subversion of the source text can be detected, not in the form of rebellion, but rather as a mild disregard. This latest translation is the first one to frequently reshuffle the text. It is also the first to subordinate meaning to style. This all indicates that despite the apparent return to tradition, the source text is no longer treated with the reverence of the past.

Still suspicious: The suspicious coincidence effect revisited

In previous work, Xu and Tenenbaum (2007a) provide evidence that learners are able to infer the subordinate meaning of a word from only positive examples of the category. Under their proposal, learners assume that examples are sampled from the true underlying category ("strong sampling''), making certain data patterns more consistent with a subordinate meaning than others (the "suspicious coincidence'' effect). More recent work (Spencer, Perone, Smith & Samuelson, 2011) questions the relevance of this finding by arguing that the effect only occurs when the examples are presented to the learner simultaneously. Across a series of 12 studies, we systematically manipulate several experimental parameters that vary between the previous studies, and successfully replicate the findings of both sets of authors. Taken together, our data suggest that the suspicious coincidence effect in fact is robust to presentation timing of examples, but is sensitive to a confound in previous experiments, namely, trial order.

Multisensory Integration: The Case of a Time Window of Gesture–Speech Integration

This experiment investigates the integration of gesture and speech from a multisensory perspective. In a disambiguation paradigm, participants were presented with short videos of an actress uttering sentences like “She was impressed by the BALL, because the GAME/DANCE….” The ambiguous noun (BALL) was accompanied by an iconic gesture fragment containing information to disambiguate the noun toward its dominant or subordinate meaning. We used four different temporal alignments between noun and gesture fragment: the identification point (IP) of the noun was either prior to (+120 msec), synchronous with (0 msec), or lagging behind the end of the gesture fragment (−200 and −600 msec). ERPs triggered to the IP of the noun showed significant differences for the integration of dominant and subordinate gesture fragments in the −200, 0, and +120 msec conditions. The outcome of this integration was revealed at the target words. These data suggest a time window for direct semantic gesture–speech integration ranging from at least −200 up to +120 msec. Although the −600 msec condition did not show any signs of direct integration at the homonym, significant disambiguation was found at the target word. An explorative analysis suggested that gesture information was directly integrated at the verb, indicating that there are multiple positions in a sentence where direct gesture–speech integration takes place. Ultimately, this would implicate that in natural communication, where a gesture lasts for some time, several aspects of that gesture will have their specific and possibly distinct impact on different positions in an utterance.

Working memory influences on cross-language activation during bilingual lexical disambiguation

This study investigated the role of verbal working memory on bilingual lexical disambiguation. Spanish–English bilinguals read sentences that ended in either a cognate or noncognate homonym or a control word. Participants decided whether follow-up target words were related in meaning to the sentences. On critical trials, sentences biased the subordinate meaning of a homonym and were followed by targets related to the dominant meaning. Bilinguals with high span were faster at rejecting unrelated targets when the sentences ended in a homonym, whereas bilinguals with low span were slower. Furthermore, error rates for bilinguals with low span showed cognate inhibition, while bilinguals with high span showed no effects of cross-language activation. Results demonstrated that bilinguals with high span benefit from shared lexical codes whether these converge on to a single semantic representation (cognates) or not (homonyms). Conversely, bilinguals with low span showed inhibition from the competing lexical codes, even when they converge onto a single semantic representation.