Morphological Differences Between Imperative and Declarative Pointing: Hand Shape, Arm Extension, and Body Posture

You may point, but do not touch: Impact of gesture-types and cognition on language in typical and atypical development

BACKGROUND

Evidence shows that the relation with the referent (object manipulation, contact/no contact pointing) and the different hand features (index finger/open palm) when pointing indicate different levels of cognitive and linguistic attainment in typical development (TD). This evidences the close link between pointing, cognition and language in TD, but this relation is understudied in autism. Moreover, the longitudinal pathway these abilities follow remains unexplored and it is unclear what specific role (predictor or mediator) pointing and cognition have in both typical and atypical language development.

AIMS

The first aim was to investigate whether pointing hand features (index finger/open palm) and relation with the referent (manipulation, contact and no contact pointing) similarly predict language in children with and without autism. The second aim was to explore whether cognition mediates the longitudinal relationship between pointing and language development.

METHODS & PROCEDURES

Sixteen children with autism, 13 children at high risk (HR) for autism and 18 TD children participated in an interactive gesture-elicitation task and were tested on standardised cognitive and expressive language batteries in a longitudinal design. A two-step analysis consisted of a stepwise linear regression and mediation analyses. First, the linear regression identified which hand features and types of relation with the referent predicted expressive language in all groups. Second, three mediation analyses (one per group) assessed the predictor/mediator role of the variables that met significance in the regression analysis.

OUTCOMES & RESULTS

Both cognition and index finger pointing were direct longitudinal predictors of further expressive language skills in the autism group. In TD and HR groups this relation was mediated by age.

CONCLUSIONS & IMPLICATIONS

Findings highlight the role of age in communicative development, but suggest a key role of cognition and index finger use in the longitudinal relationship between pointing gestures and expressive language development in children with autism. This has important clinical implications and supports the view that index finger pointing production might be a useful tool in the intervention for communicative and language abilities in autism.

WHAT THIS PAPER ADDS

What is already known on the subject There is evidence that no contact pointing is associated with complex socio-cognitive abilities that underpin communication in TD. Similarly, studies in TD show that index finger pointing is closely linked with language acquisition. However, it is unclear whether these associations are present in autism. In addition, the mediating (or predictive) role of cognition in the pointing-language relation has not yet been explored neither in typical nor in atypical development. What this paper adds to existing knowledge This paper shows that index finger pointing and cognition are direct longitudinal predictors of expressive language in the autism group. In the other groups this relation is mediated by age. This suggests that there is a window of opportunity for pointing to predict expressive language whereas the predictive value of cognition expands in development. Based on this, children with autism would share the same language predictors as TD children, but with delays. What are the potential or actual clinical implications of this work? This study reveals that index finger, age and cognition reliably predict spoken language in autism, which may indicate that early prelinguistic intervention based on pointing production and the improvement of cognitive skills might have a positive impact on spoken language in this population.

Is Conceptual Diversity an Advantage for Scientific Inquiry? A Case Study on the Concept of 'Gesture' in Comparative Psychology

Growing scientific fields often involve multidisciplinary investigations in which the same concepts may have different meanings. Here, we examine the case of 'gesture' in comparative research to depict how conceptual diversity hidden by the label 'gesture' can lead to consistently divergent interpretations in humans and nonhuman primates. We show that definitions of 'gesture' drastically differ regarding the forms of a gesture and the cognitive processes inferred from it, and that these differences emerge from implicit assumptions which have pervasive consequences on the interpretations claimed by researchers. We then demonstrate that implicit assumptions about scientific concepts can be made explicit using a finite set of operational criteria. We argue that developing theoretical definitions systematically associated with operational conceptual boundaries would allow to tackle both the challenges of maintaining high internal coherence within studies and of improving comparability and replicability of scientific results. We thus offer an easy-to-implement conceptual tool that should help ground valid comparisons between studies and serve scientific inquiry.

Different Ways of Making a Point: A Study of Gestural Communication in Typical and Atypical Early Development

Deictic pointing is among the most impaired gestures in children with autism. Research on typical development demonstrates that contact with the referent and handshape when pointing, are associated with different communicative intentions and developmental stages. Despite their importance, the morphological features of pointing remain largely unexplored in autism. The aim of the present study was to map out pointing production in autism with a focus on handshape and contact with the referent. Participants (age range = 1–6 years old) with ASD (n = 16), at high risk for autism (n = 13) and typically developing children (n = 18) interacted with their caregivers in a gesture elicitation task. Results showed that children with ASD produced fewer pointing gestures overall and fewer index finger pointing without contact with the referent compared to the typically developing children.

Lay Summary

Children with autism produce less gestures than typical children, and pointing gestures appear to be more affected than other gesture types. Whether children point using their index finger or the palm, and whether they touch or not the referent is crucial for understanding communicative intentions. This is the first study to document experimentally exactly how pointing gestures differ in autism in comparison to typical development. We found important qualitative differences in the communicative patterns of children with autism and at risk for autism, that may serve to identify potential new markers for early diagnosis. Autism Res 2021, 14: 984–996. © 2020 The Authors. Autism Research published by International Society for Autism Research and Wiley Periodicals LLC.

Contribution of Developmental Psychology to the Study of Social Interactions: Some Factors in Play, Joint Attention and Joint Action and Implications for Robotics

Children exchange information through multiple modalities, including verbal communication, gestures and social gaze and they gradually learn to plan their behavior and coordinate successfully with their partners. The development of joint attention and joint action, especially in the context of social play, provides rich opportunities for describing the characteristics of interactions that can lead to shared outcomes. In the present work, we argue that human-robot interactions (HRI) can benefit from these developmental studies, through influencing the human's perception and interpretation of the robot's behavior. We thus endeavor to describe some components that could be implemented in the robot to strengthen the feeling of dealing with a social agent, and therefore improve the success of collaborative tasks. Focusing in particular on motor precision, coordination, and anticipatory planning, we discuss the question of complexity in HRI. In the context of joint activities, we highlight the necessity of (1) considering multiple speech acts involving multimodal communication (both verbal and non-verbal signals), and (2) analyzing separately the forms and functions of communication. Finally, we examine some challenges related to robot competencies, such as the issue of language and symbol grounding, which might be tackled by bringing together expertise of researchers in developmental psychology and robotics.

Evolution and development of handedness: An Evo-Devo approach

Hand preference is a sensorimotor skill whose development both reflects and promotes the development of hemispheric lateralization for manual and cognitive functions. Extensive comparative, crosscultural, and paleoanthropological evidence demonstrates the prevalence of limb lateralized preferences across vertebrate species and the prevalence of right-handedness within hominid evolution. Many reviews of the evolution and development of human handedness have proposed adaptive explanations for its evolution. However, during the last 3 decades a new approach to understanding evolution (the Extended Evolutionary Synthesis-EES) provided a persuasive alternative to the conventional (Neo-Darwinian Synthetic Theory-ST) evolutionary and developmental accounts. EES combines modern evolutionary and developmental research (Evo-Devo) in ways that alter understanding of natural selection, adaptation, and the role of genes in development and evolution. These changes make obsolete all past accounts of the evolution and development of lateralization and handedness because EES/Evo-Devo requires new study designs. The developmental trajectories of any structural or functional trait must be specified so that it may be related to variations in the developmental trajectories of other traits. First, we describe how the EES/Evo-Devo differs from the conventional ST, particularly for understanding of how traits develop. Then, we apply Evo-Devo to the study of handedness development in infancy and its relation to the development of other cognitive functions. Finally, we argue that identifying the development of atypical traits would benefit from knowledge of the range of individual differences in typical developmental trajectories of hand-use preference and their relation to variations in the developmental trajectories of cognitive functions.

Where have all the (ape) gestures gone?

Comparative analysis of the gestural communication of our nearest animal relatives, the great apes, implies that humans should have the biological potential to produce and understand 60-70 gestures, by virtue of shared common descent. These gestures are used intentionally in apes to convey separate requests, rather than as referential items in syntactically structured signals. At present, no such legacy of shared gesture has been described in humans. We suggest that the fate of "ape gestures" in modern human communication is relevant to the debate regarding the evolution of language through a possible intermediate stage of gestural protolanguage.

Captive gorillas' manual laterality: The impact of gestures, manipulators and interaction specificity

Relationships between humans' manual laterality in non-communicative and communicative functions are still poorly understood. Recently, studies showed that chimpanzees' manual laterality is influenced by functional, interactional and individual factors and their mutual intertwinement. However, what about manual laterality in species living in stable social groups? We tackled this question by studying three groups of captive gorillas (N=35) and analysed their most frequent manual signals: three manipulators and 16 gesture types. Our multifactorial investigation showed that conspecific-directed gestures were overall more right-lateralized than conspecific-directed manipulators. Furthermore, it revealed a difference between conspecific- and human-directed gestural laterality for signallers living in one of the study groups. Our results support the hypothesis that gestural laterality is a relevant marker of language left-brain specialisation. We suggest that components of communication and of manipulation (not only of an object but also of a conspecific) do not share the same lateralised cerebral system in some primate species.

Communicative knowledge pervasively influences sensorimotor computations

Referential pointing is a characteristically human behavior, which involves moving a finger through space to direct an addressee towards a desired mental state. Planning this type of action requires an interface between sensorimotor and conceptual abilities. A simple interface could supplement spatially-guided motor routines with communicative-ostensive cues. For instance, a pointing finger held still for an extended period of time could aid the addressee’s understanding, without altering the movement’s trajectory. A more complex interface would entail communicative knowledge penetrating the sensorimotor system and directly affecting pointing trajectories. We compare these two possibilities using motion analyses of referential pointing during multi-agent interactions. We observed that communicators produced ostensive cues that were sensitive to the communicative context. Crucially, we also observed pervasive adaptations to the pointing trajectories: they were tailored to the communicative context and to partner-specific information. These findings indicate that human referential pointing is planned and controlled on the basis of partner-specific knowledge, over and above the tagging of motor routines with ostensive cues.

Communication in the second and third year of life: Relationships between nonverbal social skills and language

We aimed to investigate developmental continuities between a range of early social and communicative abilities (including gestural communication) and language acquisition in children aged between 11 and 41 months. Initiation of joint attention and imitation were strongly correlated to language comprehension and production. Moreover, the analysis of different communicative gestures revealed significant relationships between language development and the production of symbolic gestures, declarative pointing (declarative informative pointing in particular), and head nodding. Other gestures such as imperative pointing, showing, and head shaking were not found to correlate with language level. Our results also suggest that distinct processes are involved in the development of language comprehension and production, and highlight the importance of considering various characteristics of children's early communicative skills.

Current Understanding of What Infants See

The current understanding of what infants see varies greatly among healthcare and education specialists. Even among ophthalmologists and pediatric neurologists in charge of clinical examinations of infants, opinions vary on what infants perceive, recognize, and use for communication and learning. It is, therefore, of interest to review publications from several specialties to learn whether new information is available on the development of visual functions and use of vision. Ten percent of total publications on this subject are reviewed here based on the usefulness of their content for improving early diagnosis and intervention of vision disorders in infants.