What is it to pick up an upside-down cup? The dynamic interaction between actor, environment, and task in the emergence of second-order planning for object manipulation

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Issue. The way an object is grasped can be used to infer how the action was planned. Object properties (e.g., size) are considered in first-order planning; whereas second-order planning is characterized by the anticipation of secondary task demands (e.g., object use). Often referred to as the end-state comfort (ESC) effect, adults generally act to ensure a comfortable final posture. A reduced tendency for children to demonstrate ESC has been attributed to immature second-order planning abilities; however, inconsistent reports in the literature limit understanding of the course of development. Challenge. Why children display ESC in some studies, but not others, has yet to be resolved. One suggestion is that children perceive comfort differently than adults; therefore, measuring ESC in children with observational measures may not capture the development of second-order planning, per se. The proposed research will use observational and kinematic measures to provide more detailed insights. Earlier work focused on changes with age and was guided by an information processing perspective. The proposed research considers the Dynamic Systems perspective. As many factors constrain object manipulation, it is necessary to consider the dynamic interaction between actor (i.e., physical and psychological characteristics), environment (i.e., external forces surrounding the actor), and task (i.e., goals and rules of the task and equipment used) in the development of second-order object manipulation. Objectives. The proposed research will investigate interactions between characteristics of the actor (cognitive and motor function, hand size and arm length) and environment (object size and location) in traditional object manipulation tasks (cup, bar-transport, and handle-rotation tasks). This research aims to decipher how second-order planning behaviours change over the course of development from childhood to young adulthood. Methods. Experiments will include neurotypical children and adults. Observational (second-order planning, hand selection) and kinematic (3D motion tracking) data will be collected in cup, bar-transport, and handle-rotation tasks. Research in Objective 1 will track performance longitudinally. Over a series of cross-sectional investigations, Objective 2 will investigate the interaction between object size and hand size, and Objective 3 will examine interactions between object location, arm length, and hand preference. Motor proficiency, executive function, and handedness will be assessed in all participants, along with demographic (sex, age) and anthropometric (hand size, arm length) measures. Impact. This work will offer fundamental insights; inconsistent reports will be disentangled, and knowledge of the neurotypical development of reach-to-grasp for object manipulation will be created. Findings will also have practical implications (e.g., occupational therapy for children with motor difficulties).