Typological analysis of the world’s language shows that, of the 6 possible basic word orders, SOV and SVO orders are predominant, a preference supported by experimental studies in which participants improvise gestures to describe events. Silent gesture studies have also provided evidence for natural ordering patterns, where SOV and SVO orders are used selectively depending on the semantics of the event, a finding recently supported by data from natural sign languages. We present an artificial language learning task using gesture to ask to what extent preferences for natural ordering patterns, in addition to biases for regular languages, are at play during learning in the manual modality.

Though most documented sign languages make use of spaceto denote relationships between predicate arguments, studiesof emerging sign languages suggest that spatial reference doesnot emerge fully-formed but takes time to develop. We presentan artificial sign language learning experiment that expandsthe cultural evolutionary framework to investigate complexlinguistic constructions. Our results demonstrate the gradualemergence of consistent devices to distinguish between sen-tence arguments, some of which rely on iconic spatial con-trasts. These findings mirror data from emerging sign lan-guages and point to the cultural mechanisms that facilitate theevolution of complex linguistic structures.

Understanding how children acquire language remains a challenge of language research. Most research assumes that labeland referent are linked by arbitrary convention alone. However, in addition to being indisputably arbitrary, language isalso iconic. Recent evidence has shown that children are sensitive to iconic mappings and that these may bootstrap wordacquisition. However, we know little about the presence of iconicity in the language input children are exposed to. Thistalk focuses on iconicity in English CDL across vocal and visual channels: phonology (meow), prosody (loooooong),gestures (stirring) and hand actions (stirring with spoon). We discuss evidence that caregivers exploit iconicity in CDL,and use iconicity differentially depending on whether referents talked about are present or not, and familiar or not to thechild. An analysis of the type and amount of iconicity used in CDL is crucial for understanding the role of iconicity insupporting referential mapping.

We present an experimental study that examines how lexical iconicity (i.e. onomatopoeia) affects early word learning,across learning contexts. Children aged 24-36 months (N=37) were first trained on labels that are either iconic or neutralwith respect to the referent event, and then tested using a forced-choice task to select the correct referent given a label. Weassessed learning across two contexts: situated, where label and referent co-occur, and displaced, where children learn thelabel following the referent event. We predicted that iconicity would aid word learning, and would have a more facilitatoryeffect in the displaced condition, helping the child to associate label and referent. Our findings demonstrate that childrenlearn iconic labels in the experiment better than they do neutral labels. However, we find no difference across learningcontextsiconicity facilitates word learning in both situated and displaced learning scenarios.

While the grammatical use of space for referential strategies is attested across many sign languages of Western Europe, Kata Kolok, a rural sign language used in Northern Bali, has not developed anaphoric pointing in space nor agreement verbs (Engberg-Pedersen, 1993; Liddell, 2003; de Vos, 2012). To find out whether such typological differences can be explained by differences in the respective co-speech gesture systems, this preregistered study is collecting data for a cross-cultural comparison. Building on Motamedi et al. (2021), we are conducting studies in Bali and the Netherlands using an iterated learning silent gesture paradigm in which hearing people communicate transitive events using only gestures. Preliminary data indeed suggest that our Balinese participants do not employ space the same way our Dutch participants do. We will present comparative analyses and evaluate the role of co-speech gesture systems in sign language emergence in the lab or when evolving from spontaneous interaction.

Most research on how children learn the mapping betweenwords and world has assumed that language is arbitrary, andhas investigated language learning in contexts in which objectsreferred to are present in the environment. Here, we reportanalyses of a semi-naturalistic corpus of caregivers talking totheir 2-3 year-old. We focus on caregivers’ use of non-arbitrarycues across different expressive channels: both iconic(onomatopoeia and representational gestures) and indexical(points and actions with objects). We ask if these cues are useddifferently when talking about objects known or unknown tothe child, and when the referred objects are present or absent.We hypothesize that caregivers would use these cues moreoften with objects novel to the child. Moreover, they would usethe iconic cues especially when objects are absent becauseiconic cues bring to the mind’s eye properties of referents. Wefind that cue distribution differs: all cues except points are morecommon for unknown objects indicating their potential role inlearning; onomatopoeia and representational gestures are morecommon for displaced contexts whereas indexical cues aremore common when objects are present. Thus, caregiversprovide multimodal non-arbitrary cues to support children’svocabulary learning and iconicity – specifically – can supportlinking mental representations for objects and labels.

Studies have shown the importance of caregivers’ multimodal behaviours (e.g., prosody, gestures, gaze) on children’s word learning. However, most studies focus on only one specific behaviour (e.g., only prosody). Here, we investigate which multimodal behaviours used by caregivers best predict children’s word learning and vocabulary growth. Using data from the ECOLANG corpus, we analysed caregiver behaviour in semi-naturalistic interactions with their child (3 to 4 years old) in which they talked about known and unknown toys. We analysed caregivers’ (n=36) use of multimodal cues while labelling the objects, specifically their use of yes/no questions, pitch, representational gestures, pointing, object manipulations and gaze. Caregivers’ pitch, use of yes/no questions and pointing predicted children’s word learning. In particular, higher pitch when labelling unknown toys predicted immediate word learning. The degree to which caregivers used higher pitch when producing the label for known compared to unknown toys predicted both immediate learning and vocabulary growth. Furthermore, the degree to which caregivers used yes/no questions more for unknown toys predicted immediate learning, while the frequency of yes/no questions when naming unknown toys predicted vocabulary growth. Lastly, caregiver pointing also predicted immediate label learning and vocabulary growth, but in the opposite direction from prosody: the more they pointed towards known toys, the better children’s learning of novel toy labels. Other behaviours did not predict word learning. Overall, these results provide evidence for the important role of multimodal caregiver behaviours, particularly prosody, on children’s lexical development.