The Study of the Full Cycle of Gesture Interaction, The Continuum between 2D and 3D

International audienceThe goal of HCI researchers is to make interaction with computer interfaces simpler, efficient and more natural. In a context of object manipulation, we think that reaching this goal requires the ability to predict and recognize how humans grasp then manipulate objects. This is based on studies explaining human vision, reach, grasp taxonomies and manipulations. In this paper, we study the full cycle of gesture interaction using different points of view, then attempt to organize them using Norman's theory of Human Action, we link the psychology of object sensing to HCI goals and propose a simplification of gestures classes into four principal families. Our simplification of gestures classes still allow the expression of more detailed subclasses differentiated by the gesture properties

Applied force as a determining factor in lithic use-wear accrual: an experimental investigation of its validity as a method with which to infer hominin upper limb biomechanics

The advent of flake technology represented a fundamental shift in the capability of hominins to effectively access and process animal food sources. As such, the efficiency with which these tools were utilized is often widely implicated in palaeoanthropological debate, most pertinently, with regards to the evolution of upper limb biomechanics. Hence, it would then be of significance if the force, and by association efficiency, with which these tools were used is able to be determined. Presented here is the first attempt to correlate the force with which flaked tools are used to the associated microwear polish accrued on the lithics worked edge. This would potentially allow biomechanical inferences to be taken from stone artifacts and subsequently be applied to the populations that were using them. Twenty five participants of varying strength carried out a simple cutting task using small, unhafted flakes made from English chalk flint. Both maximum and mean applied force was recorded during these tasks by a sensor placed under the worked material while all other variables, including stroke count and flake size, were controlled for. Lithic polish was quantified through seven textural analyses of SEM micrographs. Results indicated that there were no statistically significant relationships between lithic polish and both maximum and mean applied force at low levels of variation. It is, however, suggested that given more archaeologically inferable experimental conditions then polish accrual may have displayed higher developmental distinctions, thus allowing lithic wear to differentiate between applied forces