Distinct effects of different visual cues on sentence comprehension and later recall: The case of speaker gaze versus depicted actions

When a look is enough: Neurophysiological correlates of referential speaker gaze in situated comprehension

Behavioral studies have shown that speaker gaze to objects in a co-present scene can influence listeners' expectations about how the utterance will unfold. These findings have recently been supported by ERP studies that linked the underlying mechanisms of the integration of speaker gaze with an utterance meaning representation to multiple ERP components. This leads to the question, however, as to whether speaker gaze should be considered part of the communicative signal itself, such that the referential information conveyed by gaze can help listeners not only form expectations but also to confirm referential expectations induced by the prior linguistic context. In the current study, we investigated this question by conducting an ERP experiment (N=24, Age:[19,31]), in which referential expectations were established by linguistic context together with several depicted objects in the scene. Those expectations then could be confirmed by subsequent speaker gaze that preceded the referential expression. Participants were presented with a centrally positioned face performing gaze actions aligned to utterances comparing two out of three displayed objects, with the task to judge whether the sentence was true given the provided scene. We manipulated the gaze cue to be either Present (toward the subsequently named object) or Absent preceding contextually Expected or Unexpected referring nouns. The results provided strong evidence for gaze as being treated as an integral part of the communicative signal: While in the absence of gaze, effects of phonological verification (PMN), word meaning retrieval (N400) and sentence meaning integration/evaluation (P600) were found on the unexpected noun, in the presence of gaze effects of retrieval (N400) and integration/evaluation (P300) were solely found in response to the pre-referent gaze cue when it was directed toward the unexpected referent with attenuated effects on the following referring noun.

Influence of Actor's Congruent and Incongruent Gaze on Language Processing

In interpreting spoken sentences in event contexts, comprehenders both integrate their current interpretation of language with the recent past (e.g., events they have witnessed) and develop expectations about future event possibilities. Tense cues can disambiguate this linking but temporary ambiguity in their interpretation may lead comprehenders to also rely on further, situation-specific cues (e.g., an actor's gaze as a cue to his future actions). How comprehenders reconcile these different cues in real time is an open issue that we must address to accommodate comprehension. It has been suggested that relating a referential expression (e.g., a verb) to a referent (e.g., a recent event) is preferred over relying on other cues that refer to the future and are not yet referentially grounded (“recent-event preference”). Two visual-world eye-tracking experiments compared this recent-event preference with effects of an actor's gaze and of tense/temporal adverbs as cues to a future action event. The results revealed that people overall preferred to focus on the recent (vs. future) event target in their interpretation, suggesting that while a congruent and incongruent actor gaze can jointly with futuric linguistic cues neutralize the recent-event preference late in the sentence, the latter still plays a key role in shaping participants' initial verb-based event interpretation. Additional post-experimental memory tests provided insight into the longevity of the gaze effects.

Integration of Social Context vs. Linguistic Reference During Situated Language Processing

Research findings on language comprehension suggest that many kinds of non-linguistic cues can rapidly affect language processing. Extant processing accounts of situated language comprehension model these rapid effects and are only beginning to accommodate the role of non-linguistic emotional, cues. To begin with a detailed characterization of distinct cues and their relative effects, three visual-world eye-tracking experiments assessed the relative importance of two cue types (action depictions vs. emotional facial expressions) as well as the effects of the degree of naturalness of social (facial) cues (smileys vs. natural faces). We predicted to replicate previously reported rapid effects of referentially mediated actions. In addition, we assessed distinct world-language relations. If how a cue is conveyed matters for its effect, then a verb referencing an action depiction should elicit a stronger immediate effect on visual attention and language comprehension than a speaker's emotional facial expression. The latter is mediated non-referentially via the emotional connotations of an adverb. The results replicated a pronounced facilitatory effect of action depiction (relative to no action depiction). By contrast, the facilitatory effect of a preceding speaker's emotional face was less pronounced. How the facial emotion was rendered mattered in that the emotional face effect was present with natural faces (Experiment 2) but not with smileys (Experiment 1). Experiment 3 suggests that contrast, i.e., strongly opposing emotional valence information vs. non-opposing valence information, might matter for the directionality of this effect. These results are the first step toward a more principled account of how distinct visual (social) cues modulate language processing, whereby the visual cues that are referenced by language (the depicted action), copresent (the depicted action), and more natural (the natural emotional prime face) tend to exert more pronounced effects.

Referential vs. Non-referential World-Language Relations: How Do They Modulate Language Comprehension in 4 to 5-Year-Olds, Younger, and Older Adults?

Age has been shown to influence language comprehension, with delays, for instance, in older adults' expectations about upcoming information. We examined to what extent expectations about upcoming event information (who-does-what-to-whom) change across the lifespan (in 4- to 5-year-old children, younger, and older adults) and as a function of different world-language relations. In a visual-world paradigm, participants in all three age groups inspected a speaker whose facial expression was either smiling or sad. Next they inspected two clipart agents (e.g., a smiling cat and a grumpy rat) depicted as acting upon a patient (e.g., a ladybug tickled by the cat and arrested by the rat). Control scenes featured the same three characters without the action depictions. While inspecting the depictions, comprehenders listened to a German sentence [e.g., Den Marienkäfer kitzelt vergnügt der Kater; literally: “The ladybug (object/patient) tickles happily the cat (subject/agent)”]. Referential verb-action relations (i.e., when the actions were present) could, in principle, cue the cat-agent and so could non-referential relations via links from the speaker's smile to “happily” and the cat's smile. We examined variation in participants' visual anticipation of the agent (the cat) before it was mentioned depending on (a) participant age and (b) whether the referentially mediated action depiction or the non-referentially associated speaker smile cued the agent. The action depictions rapidly boosted participants' visual anticipation of the agent, facilitating thematic role assignment in all age groups. By contrast, effects of the non-referentially cued speaker smile emerged in the younger adults only. We outline implications of these findings for processing accounts of the temporally coordinated interplay between listeners' age-dependent language comprehension, their interrogation of the visual context, and visual context influences.

Anticipating a future versus integrating a recent event? Evidence from eye-tracking

When comprehending a spoken sentence that refers to a visually-presented event, comprehenders both integrate their current interpretation of language with the recent event and develop expectations about future event possibilities. Tense cues can disambiguate this linking, but temporary ambiguity in these cues may lead comprehenders to also rely on further, experience-based (e.g., frequency or an actor's gaze) cues. How comprehenders reconcile these different cues in real time is an open issue. Extant results suggest that comprehenders preferentially relate their unfolding interpretation to a recent event by inspecting its target object. We investigated to what extent this recent-event preference could be overridden by short-term experiential and situation-specific cues. In Experiments 1-2 participants saw substantially more future than recent events and listened to more sentences about future-events (75% in Experiment 1 and 88% in Experiment 2). Experiment 3 cued future target objects and event possibilities via an actor's gaze. The event frequency increase yielded a reduction in the recent event inspection preference early during sentence processing in Experiments 1-2 compared with Experiment 3 (where event frequency and utterance tense were balanced) but did not eliminate the overall recent-event preference. Actor gaze also modulated the recent-event preference, and jointly with future tense led to its reversal in Experiment 3. However, our results showed that people overall preferred to focus on recent (vs. future) events in their interpretation, suggesting that while two cues (actor gaze and short-term event frequency) can partially override the recent-event preference, the latter still plays a key role in shaping participants' interpretation.