Hand preference for symbolic gestures and pointing gestures: Clues toward the understanding of language development.

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Forme, fonction et préférence manuelle des gestes communicatifs chez le jeune enfant : Comprendre les origines de la communication humaine.

Even though children’s early use of communicative gestures is recognized as being closely related to language development (e.g., Colonnesi et al., 2010), the nature of speech–gestures links still needs to be clarified. This dissertation aims to investigate the production of pointing gestures during development to determine whether the predictive and facilitative relationship between gestures and language acquisition involves specific functions of pointing, in association with specific features in terms of hand shape, gaze and accompanying vocalizations. Moreover, special attention was paid to the study of hand preferences in order to better understand the development of left hemisphere specialization for communicative behaviors. Our results revealed complex relationships between language, communicative gestures and manipulative activities depending on the function of gestures (i.e., imperative versus declarative pointing) as well as on specific stages of language acquisition. Declarative gestures were found to be more closely associated with speech development than imperative gestures, at least before the lexical spurt period. In addition, the comparison of hand-preference patterns in adults and infants showed stronger similarity for gestures than for object manipulation. The right-sided asymmetry for communicative gestures is thus established in early stages, which suggests a primary role of gestures in hemispheric specialization.Finally, our findings have highlighted the existence of a left-lateralized communication system controlling both gestural and vocal communication, which has been suggested to have a deep phylogenetic origin (e.g., Corballis, 2010). Therefore, the present work may improve current understanding of the evolutionary roots of language, including the mechanisms of cerebral specialization for communicative behaviors.Bien que l’utilisation précoce de gestes communicatifs par de jeunes enfants soit reconnue comme étant étroitement liée au développement du langage (e.g., Colonnesi et al., 2010), la nature des liens gestes–langage doit encore être clarifiée. Cette thèse a pour but d’étudier la production de gestes de pointage au cours du développement afin de déterminer si la relation prédictive et facilitatrice entre les gestes et l’acquisition du langage implique des fonctions spécifiques du pointage, en association avec des caractéristiques spécifiques en terme de forme de mains, regard et vocalisations. De plus, une attention particulière a été apportée à l’étude des préférences manuelles dans le but de mieux comprendre le développement de la spécialisation hémisphérique gauche pour les comportements communicatifs. Nos résultats ont révélé des relations complexes entre le langage, les gestes communicatifs et les activités de manipulation, qui dépendent de la fonction des gestes (i.e., pointage impératif versus déclaratif) et des étapes spécifiques de l’acquisition du langage. Les gestes déclaratifs sont plus étroitement associés au développement de la parole que les gestes impératifs, au-moins avant la période d’explosion lexicale. De plus, la comparaison des patterns de préférence manuelle chez l’enfant et l’adulte a montré une plus grande proximité pour les gestes que pour la manipulation d’objet. L’asymétrie manuelle droite pour les gestes communicatifs est ainsi établie à des stades précoces, ce qui suggère un rôle primordial des gestes dans la spécialisation hémisphérique.Finalement, nos résultats ont mis en évidence l’existence d’un système de communication dans l’hémisphère cérébral gauche contrôlant à la fois la communication gestuelle et verbale, qui pourrait avoir une origine phylogénétique ancienne (e.g., Corballis, 2010). Par conséquent, le présent travail peut améliorer notre compréhension des origines du langage, y compris des mécanismes de la spécialisation cérébrale pour les comportements communicatifs

Development of Hand Preference for Object-Directed Actions and Pointing Gestures: A Longitudinal Study between 15 and 25 months of Age

International audienceThe development of hand preferences for object-directed actions and pointing gestures was investigated in toddlers sampled bimonthly between 15 and 25 months of age. Language level was also assessed, in an attempt to examine the relationship between handedness and language development. Results did not reveal any changes over the study period in the mean Handedness Index of the whole sample, both for bimanual manipulative activities and pointing gestures. However, the categorization of participants as left-handers, right-handers, or non-lateralized revealed that most of children presented nonlinear individual trajectories in the development of hand preference. Moreover, the only significant correlations observed between hand preferences for manipulation and pointing were negative correlations between the strength of hand preferences at 19 and 21 months of age, suggesting that manipulative actions and communicative gestures are controlled by different networks in the left cerebral hemisphere. These findings are discussed in relation to the development of speech–gesture links in infancy. ß 2011 Wiley Periodicals, Inc. Dev Psychobiol 54: 105–111, 2012

Can hand preference for gestures speak for the left hemisphere?

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La communication gestuelle : Un indice du développement langagier et de la spécialisation hémisphérique

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Développement de la communication gestuelle : Quelle main, quelle fonction et quel rôle dans l’acquisition du langage ?

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Manipulating objects or communicating through gestures: Considering manual asymmetries within a complex system.

International audienceThis presentation will focus on the relationship between hand preference and hemispheric specialization for language in the human species, by describing the development of manual asymmetries for different activities: grasping and manipulating objects vs. communicating through pointing and symbolic gestures. The initial objective of this comparison was to determine whether hand preference for gestures may constitute a better predictor of hemispheric specialization for language than handedness for tool-use. But other elements may influence the emergence of manual and cerebral asymmetries, starting with the degree of goal-directedness and intentionality that characterize manual movements, as well as hemispheric specialization for functions other than language, and in particular for visual attention. Only by studying these different questions within a single frame of reference will we manage to get a more accurate view on the origin and development of human functional asymmetries

Manual asymmetries and hemispheric specialization: Insight from developmental studies

International audienceThe objective of this review is to obtain a better understanding of the relationship between manual asymmetries and hemispheric specialization by focusing on the development of hand preference and cerebral lateralization of language. We first sought to describe the development of manual asymmetries for different activities (i.e., grasping and manipulating objects vs. communicating through gestures), and the development of cerebral asymmetries, before examining available data on the association between hand preference and HS for language. We also analyzed behavioral studies on the relation between hand preference and language development, as well as more specific studies on the relation between the cerebral control of gestures and language. Finally, we aimed at providing a wider view on functional asymmetries by emphasizing the need to study hemispheric specialization for functions other than language, and in particular for visual attention

Informing through pointing: Development of communication and social understanding in children.

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