title: Influences of grasp selection in typically developing children.
abstract: When reaching towards an object, adults favour grasps which, following the intended action, end in a comfortable position even when this requires them to start in an uncomfortable position (the end-state-comfort effect). However, this strategy is not consistently used by children who instead seem to favour a minimal pre-contact rotation of the hand, even when this results in an uncomfortable end position. In terms of multiple movements, the strategies used for grip selection are unclear; adults may still grasp for end-state-comfort given their propensity to plan to the end of a movement; however, children who are less able to concatenate movement may tend to start-state-comfort movements. The current study considered grip selection in children ranging from 4 to 12 years and in a group of adults. Participants were asked to rotate a disc so that an arrow pointed towards a specific target(s), the number of sequences in a movement was increased from one to three. Planning for end-state-comfort was seen in all participants and a clear developmental trajectory was identified whereby the relative comfort of an end position could be directly predicted by age in months. Adults and 10-12-year-olds favoured an end-state-comfort strategy whereas the younger children gave equal weighting to end-state-comfort, start-state-comfort and no initial rotation strategies. All groups were able to end a movement comfortably when it was composed of three steps; however, the proportion of movements relying on an end-state-comfort strategy decreased as sequence length increase whereas the proportion of start-state-comfort and no initial rotation strategies increased. The current data support the concept that a mechanism for planning grasps may be based on motor experience.
authors.affiliation: Faculty of Health Life Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom. Electronic address: k.wilmut@brookes.ac.uk.
authors.forename: Kate
authors.initials: K
authors.lastname: Wilmut
authors.affiliation: Faculty of Health Life Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom.
authors.forename: Maia
authors.initials: M
authors.lastname: Byrne
mesh_terms: D000328:Adult; D000367:Age Factors; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D005260:Female; D006225:Hand; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012399:Rotation
keywords: Development; End-state-comfort; Grip selection; Motor planning