The impact of body-scaled information on reach and grasp actions for adults, typically developing children and children with hemiplegic cerebral palsy

The purpose of this dissertation is to examine the impacts of body-scaled information on emergent reaching and grasping patterns for children with hemiplegic cerebral palsy (CP). While previous studies indicate that one-handed and two-handed reaching patterns are influenced by an object size in relation to the maximal index finger and thumb aperture (i.e., body-scaled information) for adults and typically developing children (TDC), it requires further investigation whether similar body-scaled information is perceived for the reaching actions for children with hemiplegic CP who have altered personal constraints. Investigating the relationship between perceived body-scaled information and the emergent reaching patterns for children with hemiplegic CP may provide us with a more explicit understanding of the critical factors influencing this emergent action.;In the first experiment, we asked 20 adults and 17 TDC to reach and grasp ten different sizes of cubes to examine the body-scaled information that specifies the relation of hand size, object size, and reach and grasp patterns. More specifically, we aimed at analyzing the data statistically to investigate the differences and the variability between adults and children, which were not reported in the previous evidence. Our findings indicated that body-scaled information, expressed by dimensionless ratios, guides similar emergent reaching and grasping patterns for adults and children regardless of the differences in body dimensions. However, children have more variability of reaching and grasping patterns than adults.;In the second experiment, we asked children with hemiplegic CP to complete the same task with the aim of gaining a more thorough understanding of the impacts of body-scaled information on reaching for children with altered personal constraints. Our findings indicated that the specific dimensionless ratio was not significantly different for either preferred or non-preferred arms both within and between children with hemiplegic CP and TDC groups. Moreover, we demonstrate that the variability for the paretic and non-preferred arms is similar for both groups.;The results of this dissertation indicate that body-scaled information of object size in relation to hand size influences the emergent reaching and grasping patterns for individuals with different constraints. These findings suggest the importance of the upper limb intervention of this preschool age for children with CP because they are able to perceive similar body-scaled information for the emergent action patterns as TDC. Future research is encouraged to further systematically examine the relationship of different constraints and the body-scaled information, and how this information affects the emergent actions.