How to distinguish gesture from sign: New technology is not the answer.

Linguistic and psycholinguistic tests will be more useful than motion capture technology in calibrating the borders between sign and gesture. The analogy between motion capture (mocap) technology and the spectrograph is flawed because only vocal articulators are hidden. Although information about gradience and variability will be obtained, the technology provides less information about linguistic constraints and categories. Better models are needed to account for differences between co-speech and co-sign gesture (e.g., different degrees of optionality, existence of beat gestures).