Grounding Demonstrative Reference in Manual and Social Affordances
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This and that back in context: Grounding demonstrative reference in manual and social affordances Roberta Rocca ([email protected]) Department of Linguistics, Cognitive Science and Semiotics, Aarhus University, Jens Chr. Skous Vej 2, 8000 – Aarhus C, Denmark Mikkel Wallentin ([email protected]) Department of Linguistics, Cognitive Science and Semiotics & Center of Functionally Integrative Neuroscience, Aarhus University, Jens Chr. Skous Vej 2, 8000 – Aarhus C, Denmark Cordula Vesper ([email protected]) Department of Linguistics, Cognitive Science and Semiotics & Interacting Minds Centre, Aarhus University, Jens Chr. Skous Vej 2, 8000 – Aarhus C, Denmark Kristian Tylén ([email protected]) Department of Linguistics, Cognitive Science and Semiotics & Interacting Minds Centre, Aarhus University, Jens Chr. Skous Vej 2, 8000 – Aarhus C, Denmark Abstract communicative pointing, they play a crucial role in bootstrap- Spatial demonstratives, i.e. words like this and that, serve as ping language acquisition (Diessel, 1999; Diessel, 2006). important tools to establish joint attention, allowing Additionally, demonstratives can be regarded as cross- interlocutors to flexibly share spatial reference schemes. linguistic universals (Diessel, 2006). However, little experimental work has investigated which In contrast to other strategies for verbal referencing, such perceptual and social factors drive speakers’ choices of as the use of nouns and descriptions, demonstratives carry demonstrative forms. We used a novel experimental paradigm minimal semantic specification of the intended referent, to explore 1) the role of relative placement of competing causing their interpretation to crucially hinge on the context referents on the sagittal and lateral planes, 2) whether and how the presence of an addressee modulates the speaker’s choice of of the utterance (Diessel, 1999; Levinson, 1983). demonstrative forms. We found that the choice of demonstratives is affected by the relative position of Physical context competing referents both on the sagittal and lateral plane. When used to refer to entities in the physical context of the Furthermore, we found that the presence of an interlocutor utterance, demonstratives are typically coupled with visual shifts attraction for proximal demonstratives towards the signals such as pointing gestures (Clark, 1996; Cooperrider, shared space of reference, but only in collaborative contexts. Together, these results suggest that spatial deixis is grounded 2016) or gaze cues (Perea-García et al., 2017), which deliver in a contrastive organization of space tightly coupled to manual crucial information on the location of the intended referents and social affordances. relative to the speaker. In an EEG/ERPs experiment, Stevens & Zhang (2012) reported N400 effects for incongruence Keywords: demonstratives; social cognition; spatial cognition; spatial deixis between demonstratives and object location only when the speaker and addressee in the scene established joint gaze on the referent. As demonstratives are used as attention aligning devices, participants perceived the absence of shared gaze as Introduction a violation in their use. The ability to establish joint attention on objects or locations With the exception of very few languages, all is a fundamental building block of human sociality demonstrative systems explicitly encode at least a minimal (Tomasello, 2005). A wide spectrum of everyday activities dyadic contrast between proximal and distal referents. More relies on the ability to coordinate on and navigate joint complex demonstrative systems display either more fine- attentional scenes. Natural languages are endowed with a grained distance-based contrasts, e.g. via explicit lexical large inventory of strategies that can be used for spatial encoding of medial distances from the speaker, or additional referencing and coordination purposes (Tylén et al., 2010). person-oriented contrasts, providing, for example, some Among them, spatial demonstratives, i.e. words like this and specification on the position of referents relative to the that, stand out, as attentional alignment is integral to their use addressee (Diessel, 1999). (Diessel 1999). Demonstratives are prominent items in Previous studies have experimentally investigated the linguistic interaction. They are among the first lexical items motivations for this distance-based distinction, and provided to be mastered during development, and alongside empirical evidence for a mapping between the proxi- mal/distal contrast in demonstrative systems and a functional 960 representation of space in body-centered coordinates. In a centered on the conversational dyad, rather than on the series of studies relying on a paradigm labelled the memory speaker alone. This proposal is in line with accounts of game, Coventry and colleagues asked participants to point at linguistic reference as a collaborative process (Clark, 1996). referents located at varying distances from the speaker on the As pointed out within such frameworks, speakers design their sagittal axis and to refer to them by either a proximal or a communicative acts by actively taking into account the distal demonstrative (Coventry et al, 2008; Coventry et al., addressee’s perspective and their common ground (Clark et 2014; Gudde et al., 2016). They established a mapping al., 1983; Clark and Bangerter 2004). between distance-based contrasts in demonstratives and the distinction between peripersonal and extrapersonal space, The present study consistent across a variety of genetically heterogeneous The aim of the present study was to address a number of languages. outstanding questions related to how physical and social Interestingly, the choice of demonstratives along the context influence demonstrative use. First, as previous proximal / distal axis inherits the characteristic flexibility of experiments simplified reference resolution to single-referent the boundary between peripersonal and extrapersonal space contexts (which would not capture naturalistic situations of (Coventry et al., 2014). It has been shown that the use of demonstrative use), we aimed to test how the presence of proximal demonstratives is sensitive to manipulations of the competing referents modulates the choice of demonstrative scope of peripersonal space achieved with tool use (Longo & forms in interaction. We hypothesized that proximal Lourenco, 2006). Moreover, just like physical distance and demonstratives are more likely to be used for referents object attributes such as graspability and affective valence relatively closer to the speaker on the sagittal axis. interact in perceptual judgements of reachability (Valdés- Secondly, existing paradigms have put the emphasis Conroy et al., 2012), the choice of demonstratives in dyadic exclusively on the specifics of spatial deixis along the sagittal systems is affected by perceptual parameters of the referent axis. It is, however, widely established that biomechanical (e.g. visibility), as well as by psychological parameters such constraints, such as handedness, may be a prominent source as ownership and familiarity (Coventry et al., 2014). of asymmetries in perceptual space. Perceptual However, spatial demonstratives resist a rigid mapping representations of peripersonal space underlying planning onto body-centered representations of physical space. and execution of reaching movements rely on dynamic Bonfiglioli et al. (2009) exploited well-established transformations between hand-centered and retinocentric interference effects between word meaning and movement coordinates (Makin et al., 2012). In the light of the hypothesis planning and execution (Glover et al., 2004) to explore the that the proximal/distal contrast is grounded on functional semantics of spatial deixis. Participants were primed with representations of space for reach and grasp (Coventry et al., either a proximal demonstrative or a distal demonstrative, 2014), a hand-centered frame of reference might indeed be then performed reach-for-grasp movements for objects crucial for the understanding of demonstrative reference. If located at two different distances in peripersonal space. They the hand, rather than the locus of foveal fixation or the head, found that incongruence between demonstratives and spatial is the center of the deictic frame of reference, a lateralized locations affected reaction times in movement execution. bias for proximal demonstratives towards the hand used for Together, these studies suggest that the use of demonstratives pointing would be expected which has not been captured by is not alone determined by physical distance between a single previous experimental paradigms. Given these previous referent and the speaker, but rather reflects a flexible and findings, and with all our participants being right-handed, we context-sensitive implementation of the contrastive potential hypothesized a right-lateralized bias in favor of proximal of the demonstrative system as a whole (Kemmerer, 1999; demonstratives. 2006). Last, existing literature has tackled deixis in individual contexts, without the presence of a conversational partner. Social context However, while some languages lexicalize distinctions In a recent series of EEG studies, Peeters and colleagues between locations of referents relative to an addressee, (2015) have questioned purely egocentric proximity-based demonstrative choice in languages lacking an explicit accounts of spatial deixis and stressed the role of the social encoding of the addressee’s