Producing and perceiving gestures conveying height or shape

In this paper, we analyze single-handed hold gestures that convey either the height or the shape of an object. The analyses include (1) differentiating which parts of the hands are profiled in each gesture, (2) considering whether these parts are occluded by other fingers, and (3) deriving predictions from (1) and (2) with regard to what hand shape characteristics favor height or shape gestures. In a production experiment, we asked participants to indicate either the height of a small ball or its shape, using only the index finger and the thumb. As predicted, the middle, ring and little finger were more curled in for height gestures. For shape gestures, those three fingers were more raised. In two perception experiments, participants viewed virtual hands from a computer-generated continuum of hand-shape stimuli. We found that if the middle, ring and little finger were more curled in, participants were more likely to interpret a gesture as indicating height. Our results pose new questions with regard to the relation between the physical form of a gesture and the inferred imaginary forms that are involved in deriving meaning from a gesture.