A basic study of dynamic recognition of human facial expressions

In order to develop an active human interface (AHI) for heart-to-heart communication between machine and human being, we´ve been investigating the machine recognition of human emotions from facial expressions. This paper aims at clarifying the difference between static and dynamic recognition of facial expressions and investigating the characteristics of their dynamic recognition. In the first place, we obtain the 11 facial images for each of 6 basic expressions, sequentially changing from neutral to one of basic expressions (apex). Then, for comparison, we undertake static visual recognition tests by showing facial images to subjects, and then, by using the sequentially changing images, we also perform dynamic recognition tests. The comparison between static and dynamic recognition results reveals no difference. We further prepare two types of sequential facial images; time-wise sequential images changing from neutral to apex (UP) and from apex to neutral (DOWN). The results of dynamic recognition tests by using UP and DOWN sequential images reveal the fact that the recognition point in changing facial expression differs between the UP and DOWN time-sequential face image data, i.e., there exists a hysteresis in human dynamic recognition of facial expressions