Development of collection precedes targeted reaching: resting shapes of the hands and digits in 1-6-month-old human infants.
Hand shaping is an important part of many skilled hand movements and includes a number of hand shapes prominent amongst which is collection. In collection, the hand is held with the digits lightly closed and flexed. It occurs when the hand is at rest and it occurs as the hand is transported to a target in behaviors such as reaching for an object, crawling, and climbing a ladder. Collection also frequently precedes hand gestures associated with speaking. The development of collection in infancy has not been described but it might be predicted that collection should develop before grasping and reaching movements. The present study examines the development of collection and arm position during the first 6 months of infant development. Infants were filmed while awake and photographed while asleep and hand shape and the hands location relative to the torso was documented. Collection associated with a relaxed position of the arm became increasingly prominent over the first 4 weeks of life in both awake and sleeping infants. It replaces a clenched (spastic) fist that was typically held proximal to the upper torso. The results are discussed in relation to the idea that the development of collection is an important antecedent to other hand shaping movements, especially skilled movements of grasping and reaching.
Sacrey
Lori-Ann R
LA
Department of Neuroscience, Canadian Centre for Behavioural Neuroscience, University of Lethbridge, 4401 University Drive W, Lethbridge, Alberta, Canada T1K 3M4. lori.sacrey@uleth.ca
Whishaw
Ian Q
IQ
D001132:Arm / Q000254:growth & development; D002657:Child Development; D005260:Female; D005385:Fingers / Q000254:growth & development*; D006225:Hand / Q000254:growth & development*; D006801:Humans; D007223:Infant; D008297:Male; D009048:Motor Skills; D014741:Video Recording / Q000379:methods