Our research aims to clarify the mechanism of sensitiveness in human vision by developing a computerized facial caricaturing system, and at the same time to examine the significance of the usage of facial caricatures as a nonverbal interface media. To enforce the skill of our computerized caricaturing system, called PICASSO, as a flexible caricaturing tool, it is essential that the system be able to have various kinds of facial expressions added. In this paper, a dynamic mechanism to change emotional facial expressions is realized by using a set of different mean faces and the piece-wise linear transform method. In many cases the caricatures are evaluated to be well by humans and also by the system. Furthermore, the effectiveness of this facial emotion in caricature was confirmed in the cognitive experiments for the 'talk' environment in the network.