Rhythm and synchrony in early development, and signs of autism and Rett syndrome in infancy

By Colwyn Trevarthen and Stuart Daniel

Department of Psychology, The University of Edinburgh, Scotland, UK

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We first summarise evidence on age-related changes of intentions in normally developing infants.  Infants actively search for experience and show selective awareness of the world from birth, and they imitate expressions of communication.  As their movements become stronger and more versatile, they express pleasure in games with familiar others, engaging with the rhythms of their actions.   Awareness of the interests and emotions of other persons and of their sympathetic responses leads around 9 months to ‘secondary intersubjectivity’, defined as the deliberate sharing of purposes, experience and thinking, by ‘co-operative awareness’ with ‘joint attention’.  The evidence from infant behaviours reveals an intrinsically regulated programme of brain development for control of actions that needs responsive support from human companions.  We interpret the age-related developments in intentions and socially responsive behaviour with data from home movies of infants who later develop autism or Rett syndrome.  Detailed evidence on how problems in motivation, motor co-ordination and awareness may emerge from faulty brain development is given from a case study made of films of monozygotic twin girls at 11 months, one of whom became autistic.  Changes in Twin A’s attention, motor tonus, initiative and emotion, reduce her prospective control of movements and her anticipations in awareness compared to her sister.  These changes, reflected in the child’s asynchronous social behaviour, frustrate the father’s attempts to support her attempts to walk, share toys, or play a game, confusing his anticipations, and this further reduced mutual attention and joint activity.  The findings illustrate how a disorder of core motive processes in an infant’s brain can give rise to a disturbance of co-ordinated action and selective interest, and how this can handicap emergence of sympathetic awareness, rhythms of communication and cooperative learning.  Observations of the development in the first year of girls with Rett syndrome reveal similar changes in motor coordination, attention and communicative initiative, but there are subtle differences.
We conclude with recommendations for an approach to early diagnosis and treatment, for the whole range of developmental brain disorders, including Rett syndrome and autism, that attempts to identify and support residual capacities for sympathetic motivation and collaborative learning – one that deliberately tries to support motor and communicative functions in a Vygotskian ‘zone of proximal development’ for the growing infant brain.