Difference Between Gestural Productions And Visual Estimations Of Oriented-line Lengths

Gestures have been widely used in human-computer interaction(HCI). Research on perception of gestural movements are necessary for future improvement on gesture-based interaction system. In this study, researcher focused on different spatial coding for vocal(visual) estimations and gestural(kinesthetic) productions of oriented-line lengths. Researcher tried to reveal that nonlinearity of correlation between perceived lengths and physical lengths is continuously variable in different judge situation.In Experiment 1, three different judge situation were included:1.judge lengths by vocal; 2.produce lengths by finger span; 3.produce lengths by finger span without visual-feedback on fingers. The results show that with increased involvement of kinesthetic perception, sensory magnitudes tend to be increasing nonlinearly related with stimuli magnitudes.In Experiment 2, spatial coding for gestural productions were manipulated by different orientations of finger movement. There were three varieties of productions:skilled productions, unskilled productions and natural productions. It was found that subjects’ unskilled judgments were significantly longer than skilled judgments. Meanwhile, they produced more estimate error in unskilled condition. According to Stevens’ Power Law, smaller exponents were given by unskilled productions comparing to skilled productions. During trajectory analysis of productions, unskilled productions were found to be more continuous than skilled productions. In Experiment 3, skilled productions were suggested to be more accord with subjects’ perceptual experience than unskilled productions.In length estimate error approach, egocentric errors are more (positively) correlated with stimuli lengths when length judgments tend to be "kinesthetic" or "action-oriented". On the contrary, allocentric errors become more (negatively) correlated with physical lengths with increased involvement of "perception-oriented" length judgments.Above all, continuous variation of correlation between perceived lengths and stimuli lengths are found in different kinds of judgments. What’s more, evidences from length estimate error show that visual and kinesthetic lengths are encoded differently.