THE DEVELOPMENT OF PREHENSION IN INFANTS - HALVERSON REVISITED

The development of prehension was studied in babies aged between 6 and 20 months in a partial replication of the classic study by Halverson (1931). In our study the objects to be grasped were spheres and cubes carefully graded to allow comparisons of grips with object shape and s ize controlled. The trend noted by Halverson, for power grips to decre ase and precision grips to increase, was replicated so chat by the sec ond year precision grasping is the dominant mode of prehension. Howeve r, the transition to precision grasping appears to occur by selection from a developmentally prior mixture of power and precision grips. In comparing spheres and cubes object size was the most important factor influencing grip selection but object shape also had a lesser influenc e. Object size may have acted as a scaling factor for grip selection. The findings are discussed in relation to a selectionist approach to t he development of prehension.