Modeling prehensile actions for the evaluation of Tangible User Interfaces

Prehension, or reaching-to-grasp is a very common movement performed by users of tangible user interfaces (TUIs) because through this movement users can manipulate tangible artifacts. Here we present an experiment that provides evidence towards the hypothesis that prehensile movements can be modeled based on the amplitude of the prehension movement. We then explore consequences of this evidence on the modeling and evaluation of TUIs using tools that can predict task completion times, such as goals, operators, methods and selection rules (GOMS), as well as the implications for TUIs compared to Direct Manipulation Interfaces.