Publications

Abstract

A foundational assumption of human communication is that speakers should say as much as necessary, but no more. Yet, people routinely produce redundant adjectives and their propensity to do so varies cross-linguistically. Here, we propose a computational theory, whereby speakers create referential expressions designed to facilitate listeners’ reference resolution, as they process words in real time. We present a computational model of our account, the Incremental Collaborative Efficiency (ICE) model, which generates referential expressions by considering listeners’ real-time incremental processing and reference identification. We apply the ICE framework to physical reference, showing that listeners construct expressions designed to minimize listeners’ expected visual search effort during online language processing. Our model captures a number of known effects in the literature, including cross-linguistic differences in speakers’ propensity to over-specify. Moreover, the ICE model predicts graded acceptability judgments with quantitative accuracy, systematically outperforming an alternative, brevity-based model. Our findings suggest that physical reference production is best understood as driven by a collaborative goal to help the listener identify the intended referent, rather than by an egocentric effort to minimize utterance length.

Abstract

When people hear words for objects with prototypical colors (e.g., ‘banana’), they look at objects of the same color (e.g., lemon), suggesting a link in comprehension between objects and their prototypical colors. However, that link does not carry over to production: The experimental record also shows that when people speak, they tend to omit prototypical colors, using color adjectives when it is informative (e.g., when referring to clothes, which have no prototypical color). These findings yield an interesting prediction, which we tested here: while prior work shows that people look at yellow objects when hearing ‘banana’, they should look away from bananas when hearing ‘yellow’. The results of an offline sentence-completion task (N = 100) and an online eye-tracking task (N = 41) confirmed that when presented with truncated color descriptions (e.g., ‘Click on the yellow…’), people anticipate clothing items rather than stereotypical fruits. A corpus analysis ruled out the possibility that this association between color and clothing arises from simple context-free co-occurrence statistics. We conclude that comprehenders make linguistic predictions based not only on what they know about the world (e.g., which objects are yellow) but also on what speakers tend to say about the world (i.e., what content would be informative).

Abstract

In the Dot task, children and adults involuntarily compute an avatar’s visual perspective, which has been interpreted by some as automatic Theory of Mind. This interpretation has been challenged by other researchers arguing that the task reveals automatic attentional orienting. Here we tested a new interpretation of previous findings: the seemingly automatic processes revealed by the Dot task result from the high Executive Control demands of this verification paradigm, which taxes short-term memory and imposes perspective-switching costs. We tested this hypothesis in three experiments conducted in India with newly sighted children (Experiment 1; N = 5; all girls), neurotypical children (Experiment 2; ages 5–10; N = 90; 38 girls) and adults (Experiment 3; N = 30; 18 women) in a highly simplified version of the Dot task. No evidence of automatic perspective-taking was observed, although all groups revealed perspective-taking costs. A newly sighted child and the youngest children in our sample also showed an egocentric bias, which disappeared by age 10, confirming that visual perspective taking develops during the school years. We conclude that the standard Dot task imposes such methodological demands on both children and adults that the alleged evidence of automatic processes (either mindreading or domain general) may simply reveal limitations in Executive Control.

Abstract

In referential communication, gaze is often interpreted as a social cue that facilitates comprehension and enables word learning. Here we investigated the degree to which head turning facilitates gaze following. We presented participants with static pictures of a man looking at a target object in a first and third block of trials (pre- and post-intervention), while they saw short videos of the same man turning towards the target in the second block of trials (intervention). In Experiment 1, newly sighted individuals (treated for congenital cataracts; N = 8) benefited from the motion cues, both when comparing their initial performance with static gaze cues to their performance with dynamic head turning, and their performance with static cues before and after the videos. In Experiment 2, neurotypical school children (ages 5–10 years; N = 90) and adults (N = 30) also revealed improved performance with motion cues, although most participants had started to follow the static gaze cues before they saw the videos. Our results confirm that head turning is an effective social cue when interpreting new words, offering new insights for a pathways approach to development.

Abstract

Previous research has pointed at communicative efficiency as a possible constraint on language structure. Here we investigated adjective position in American Sign Language (ASL), a language with relatively flexible word order, to test the incremental efficiency hypothesis, according to which both speakers and signers try to produce efficient referential expressions that are sensitive to the word order of their languages. The results of three experiments using a standard referential communication task confirmed that deaf ASL signers tend to produce absolute adjectives, such as color or material, in prenominal position, while scalar adjectives tend to be produced in prenominal position when expressed as lexical signs, but in postnominal position when expressed as classifiers. Age of ASL exposure also had an effect on referential choice, with early-exposed signers producing more classifiers than late-exposed signers, in some cases. Overall, our results suggest that linguistic, pragmatic and developmental factors affect referential choice in ASL, supporting the hypothesis that communicative efficiency is an important factor in shaping language structure and use.

Abstract

This study explores the connection between language and social cognition by empirically testing different typological analyses of various demonstrative systems. Linguistic typology classifies demonstrative systems as distance-oriented or person-oriented, depending on whether they indicate the location of a referent relative only to the speaker, or to both the speaker and the listener. From the perspective of social cognition, speakers of languages with person-oriented systems must monitor their listener’s spatial location in order to accurately use their demonstratives, while speakers of languages with distance-oriented systems can use demonstratives from their own, egocentric perspective. Resolving an ongoing controversy around the nature of the Spanish demonstrative system, the results of Experiment 1 confirmed that this demonstrative system is person oriented, while the English system is distance oriented. Experiment 2 revealed that not all three-way demonstrative systems are person oriented, with Japanese speakers showing sensitivity to the listener’s spatial location, while Turkish speakers did not show such an effect in their demonstrative choice. In Experiment 3, Catalan-Spanish bilinguals showed sensitivity to listener position in their choice of the Spanish distal form, but not in their choice of the medial form. These results were interpreted as a transfer effect from Catalan, which revealed analogous results to English. Experiment 4 investigated the use of demonstratives to redirect a listener’s attention to the intended referent, which is a universal function of demonstratives that also hinges on social cognition. Japanese and Spanish speakers chose between their proximal and distal demonstratives flexibly, depending on whether the listener was looking closer or further from the referent, whereas Turkish speakers chose their medial form for attention correction. In conclusion, the results of this study support the view that investigating how speakers of different languages jointly use language and social cognition in communication has the potential to unravel the deep connection between these two fundamentally human capacities.

Abstract

We investigated the effect of optionality on the acquisition of new/given markers, with a special focus on grammaticalization as a stage of optional use of the emerging form. To this end, we conducted a narrative-elicitation task with 5-year-old children and adults across four typologically-distinct languages with different new/given markers: English, Hindi, Mandinka and Spanish. Our starting assumption was that the Hindi numeral ‘ek’ (one) is developing into an indefinite article, which should delay children’s acquisition because of its optional use to introduce discourse referents. Supporting the Optionality Hypothesis, Experiment 1 revealed that obligatory markers are acquired earlier than optional markers. Experiment 2 focused on Hindi and showed that 10-year-old children’s use of ‘ek’ to introduce discourse characters was higher than 5-year-olds’ and comparable to adults’, replicating this pattern of results in two different cities in Northern India. Lastly, a follow-up study showed that Mandinka-speaking children and adults made use of all available discourse markers when tested on a familiar story, rather than with pictorial prompts, highlighting the importance of using culturally-appropriate methods of narrative elicitation in cross-linguistic research. We conclude by discussing the implications of article grammaticalization for common ground management in a speech community.

Abstract

While most research on scalar implicature has focused on the lexical scale “some” vs “all,” here we investigated an understudied scale formed by two syntactic constructions: categorizations (e.g., “Wilma is a nurse”) and comparisons (“Wilma is like a nurse”). An experimental study by Rubio-Fernandez et al. (2017) showed high rates of logical responses to superordinate comparisons, even though they are underinformative when interpreted pragmatically (e.g., “A robin is like a bird” implies that a robin is not a bird). Based on recent studies on enrichment priming, we predicted that including “some” and “all” statements (which typically elicit high rates of pragmatic responses) in sentence verification and sentence evaluation tasks would introduce an informativity bias, increasing pragmatic responses to superordinate comparisons. The results of three Web-based experiments supported our predictions, showing that different scalar expressions not only give rise to different rates of scalar implicatures, but can also affect the degree to which an experimental task elicits pragmatic reasoning.

Abstract

Demonstratives—simple referential devices like this and that—are linguistic universals, but their meaning varies cross-linguistically. In languages like English and Italian, demonstratives are thought to encode the referent’s distance from the producer (e.g., that one means “the one far away from me”),
while in others, like Portuguese and Spanish, they encode relative distance from both producer and receiver (e.g., aquel means “the one far away from both of us”). Here we propose that demonstratives are also sensitive to the receiver’s focus of attention, hence requiring a deeper form of social cognition
than previously thought. We provide initial empirical and computational evidence for this idea, suggesting that producers use
demonstratives to redirect the receiver’s attention towards the intended referent, rather than only to indicate its physical distance.

Abstract

Human social intelligence relies on our ability to infer other people’s mental states such as their beliefs, desires,and intentions. While people are proficient at mental state inference from physical action, it is unknown whether people can make inferences of comparable granularity from simple linguistic events. Here, we show that people can make quantitative mental state attributions from simple referential expressions, replicating the fine-grained inferential structure characteristic of nonlinguistic theory of mind. Moreover, people quantitatively adjust these inferences after brief exposures to speaker-specific speech patterns. These judgments matched the predictions made by our computational model of theory of mind in language, but could not be explained by a simpler qualitative model that attributes mental states deductively. Our findings show how the connection between language and theory of mind runs deep, with their interaction showing in one of the most fundamental forms of human communication: reference.

Abstract

We hypothesize that contrast perception works as a visual heuristic, such that when speakers perceive a significant degree of contrast in a visual context, they tend to produce the corresponding adjective to describe a referent. The contrast perception heuristic supports efficient audience design, allowing speakers to produce referential expressions with minimum expenditure of cognitive resources, while facilitating the listener's visual search for the referent. We tested the perceptual contrast hypothesis in three language-production experiments. Experiment 1 revealed that speakers overspecify color adjectives in polychrome displays, whereas in monochrome displays they overspecified other properties that were contrastive. Further support for the contrast perception hypothesis comes from a re-analysis of previous work, which confirmed that color contrast elicits color overspecification when detected in a given display, but not when detected across monochrome trials. Experiment 2 revealed that even atypical colors (which are often overspecified) are only mentioned if there is color contrast. In Experiment 3, participants named a target color faster in monochrome than in polychrome displays, suggesting that the effect of color contrast is not analogous to ease of production. We conclude that the tendency to overspecify color in polychrome displays is not a bottom-up effect driven by the visual salience of color as a property, but possibly a learned communicative strategy. We discuss the implications of our account for pragmatic theories of referential communication and models of audience design, challenging the view that overspecification is a form of egocentric behavior.

Abstract

Similes require two different pragmatic skills: appreciating the intended similarity and deriving a scalar implicature (e.g., “Lucy is like a parrot” normally implies that Lucy is not a parrot), but previous studies overlooked this second skill. In Experiment 1, preschoolers (N = 48; ages 3–5) understood “X is like a Y” as an expression of similarity. In Experiment 2 (N = 99; ages 3–6, 13) and Experiment 3 (N = 201; ages 3–5 and adults), participants received metaphors (“Lucy is a parrot”) or similes (“Lucy is like a parrot”) as clues to select one of three images (a parrot, a girl or a parrot-looking girl). An early developmental trend revealed that 3-year-olds started deriving the implicature “X is not a Y,” whereas 5-year-olds performed like adults.

Abstract

A psychophysical analysis of referential communication establishes a causal link between a visual stimulus and a speaker’s perception of this stimulus, and between the speaker’s internal representation and their reference production. Here, I argue that, in addition to visual perception and language, social cognition plays an integral part in this complex process, as it enables successful speaker-listener coordination. This pragmatic analysis of referential communication tries to explain the redundant use of color adjectives. It is well documented that people use color words when it is not necessary to identify the referent; for instance, they may refer to “the blue star” in a display of shapes with a single star. This type of redundancy challenges influential work from cognitive science and philosophy of language, suggesting that human communication is fundamentally efficient. Here, I explain these seemingly contradictory findings by confirming the visual efficiency hypothesis: redundant color words can facilitate the listener’s visual search for a referent, despite making the description unnecessarily long. Participants’ eye movements revealed that they were faster to find “the blue star” than “the star” in a display of shapes with only one star. A language production experiment further revealed that speakers are highly sensitive to a target’s discriminability, systematically reducing their use of redundant color adjectives as the color of the target became more pervasive in a display. It is concluded that a referential expression’s efficiency should be based not only on its informational value, but also on its discriminatory value, which means that redundant color words can be more efficient than shorter descriptions.

Abstract

Pragmatic theories and computational models of reference must account for people’s frequent use of redundant color adjectives (e.g., referring to a single triangle as “the blue triangle”). The standard pragmatic view holds that the informativity of a referential expression depends on pragmatic contrast: Color adjectives should be used to contrast competitors of the same kind to preempt an ambiguity (e.g., between several triangles of different colors), otherwise they are redundant. Here we propose an alternative to the standard view, the incremental efficiency hypothesis, according to which the efficiency of a referential expression must be calculated incrementally over the entire visual context. This is the first theoretical account of referential efficiency that is sensitive to the incrementality of language processing, making different cross-linguistic predictions depending on word order. Experiment 1 confirmed that English speakers produced more redundant color adjectives (e.g., “the blue triangle”) than Spanish speakers (e.g., “el triángulo azul”), but both language groups used more redundant color adjectives in denser displays where it would be more efficient. In Experiments 2A and 2B, we used eye tracking to show that pragmatic contrast is not a processing constraint. Instead, incrementality and efficiency determine that English listeners establish color contrast across categories (BLUE SHAPES > TRIANGULAR ONE), whereas Spanish listeners establish color contrast within a category (TRIANGLES > BLUE ONE). Spanish listeners, however, reversed their visual search strategy when tested in English immediately after. Our results show that speakers and listeners of different languages exploit word order to increase communicative efficiency.

Abstract

Language and Theory of Mind come together in communication, but their relationship has been intensely contested. I hypothesize that pragmatic markers connect language and Theory of Mind and enable their co-development and co-evolution through a positive feedback loop, whereby the development of one skill boosts the development of the other. I propose to test this hypothesis by investigating two types of pragmatic markers: demonstratives (e.g., ‘this’ vs. ‘that’ in English) and articles (e.g., ‘a’ vs. ‘the’). Pragmatic markers are closed-class words that encode non-representational information that is unavailable to consciousness, but accessed automatically in processing. These markers have been associated with implicit Theory of Mind because they are used to establish joint attention (e.g., ‘I prefer that one’) and mark shared knowledge (e.g., ‘We bought the house’ vs. ‘We bought a house’). Here I develop a theoretical account of how joint attention (as driven by the use of demonstratives) is the basis for children’s later tracking of common ground (as marked by definite articles). The developmental path from joint attention to common ground parallels language change, with demonstrative forms giving rise to definite articles. This parallel opens the possibility of modelling the emergence of Theory of Mind in human development in tandem with its routinization across language communities and generations of speakers. I therefore propose that, in order to understand the relationship between language and Theory of Mind, we should study pragmatics at three parallel timescales: during language acquisition, language use, and language change.

Abstract

Kammermeier and Paulus (2018) report a partial replication of the results of Rubio-Fernández and Geurts (2013) but present their study as a failed replication. Paulus and Kammermeier (2018) insist on a negative interpretation of their findings, discrediting the Duplo task against their own empirical evidence. Here I argue that Paulus and Kammermeier may try to make an impactful contribution to the field by adding to the growing skepticism towards early Theory of Mind studies, but fail to make any significant contribution to our understanding of young children’s Theory of Mind abilities.

Abstract

For almost two decades, the poor performance observed with the so-called Director task has been interpreted as evidence of limited use of Theory of Mind in communication. Here we propose a probabilistic model of common ground in referential communication that derives three inferences from an utterance: what the speaker is talking about in a visual context, what she knows about the context, and what referential expressions she prefers. We tested our model by comparing its inferences with those made by human participants and found that it closely mirrors their judgments, whereas an alternative model compromising the hearer’s expectations of cooperativeness and efficiency reveals a worse fit to the human data. Rather than assuming that common ground is fixed in a given exchange and may or may not constrain reference resolution, we show how common ground can be inferred as part of the process of reference assignment.