Pre-School Age: Development of Hand Laterality and Language

The proposed study will be a continuation of a detailed longitudinal research project on normal motor and language development with the aim to shed new light on the development of hand preference, lateralization of language, in particular word naming, and the relationship between both. It is a unique sample of the development of about thirty optimal and less than optimal children, who were already examined intensively sixteen times. Our main focus for the present study is pre-school children. Laterality is evident early on in life and hand-use preference becomes apparent by three years of age showing changes until about eight to eleven years of age. Laterality of manual behaviour is of interest for the implications it has for lateralization of brain function and also from a clinical and practical point of view. Considerable individual variability is reported for the precise age at which normal children reach language milestones, such as the onset of expressive language. In addition, it is of the utmost importance from a clinical point of view that language impairment be detected early in order to facilitate early intervention. It is a well known fact that different portions of the nervous system mediate different elements of language, such as comprehension, production, lexical development or prosody. Bilateral representation is assumed for the first years of life. Left-hemisphere dominance may actually emerge fairly late in the development of language. We propose to address questions concerning individual developmental trajectories of the hand preference for daily and unpractised tasks, the lateralization during specific language tasks, such as word naming as well as the relation between both. Each examination will consist of various age specific methods, such as neurological, motor and language tests and observations. In addition, event-related brain potentials (ERP) and EEG coherence analysis will be used to describe brain activations concerning the lateralization of language processing and hand dominance. They are non-invasive techniques to study developmental changes in the organisation of brain activity and are especially suited for studying infants and toddlers.

The FWF Project P16984-B02 (preschool children: development of hand laterality and language) was part of a detailed longitudinal research project on normal and impaired motor and language development. The aim was to shed light on the development of gross and fine motor proficiency, hand preference, language, and cognition as well as their inter-relationship. Sixty-two optimal and less than optimal children were seen and investigated 19 times from birth into the school age. In order to assess early lexical development we adapted the parental report forms for Austrian-German and developed the Austrian Communicative Development Inventories. We found a high correlation between parental reports and direct assessment of the child`s early words, understood and spoken. Early word production was related to parental education and vocational levels. A birth order effect on early lexical development favoured first-borns. Our study did not reveal gender differences. The need of neonatal intensive care was associated with a delay in early lexical acquisition. Although so-called Late Talkers (i.e. children with a delayed lexical knowledge during the second year of life) had a normal (but not optimal) lexical knowledge at the preschool and the school age, they were less lateralised at that age (i.e. the hand use preference was less clear). Furthermore, they are at higher risk to exhibit minor neurological deficits such as problems in fine manipulation, balance, and/or movement coordination. Fine manipulative disabilities during preschool and school age could be already identified by a movement analysis during infancy. Infants, who later develop moderate or severe neurological problems (due to acquired brain lesions or due to brain impairments caused by genetic mutations) or do have specific fine manipulative disabilities show specific abnormal movement patterns during their first months of life. In addition, reaching for different objects during the first months of life tells about hand use preference during preschool and school age. On the other hand, manual tasks, such as the pegboard task or the building a tower task do not tell about hand use preference. Hence, a battery of carefully selected tasks rather than a few single tasks are needed to assess hand use preference.