Non Verbal Communication Devices and Language Acquisition or Re-acquisition

The author is a mathematician, trained in logic and recursion theory. When confronted to the needs of children in special education (behavioural problems, mental retardation, x-fragile syndrome, language disorders) he naturally decided to use logico-mathematical tools with them. He created an adapted methodology to use these tools in a nearly non verbal way. This new approach is called the "Non Verbal Communication Device" approach (NVCD). The purpose of this chapter is to describe and define the NVCD like approaches, the cognitive observations realized with them and then to try to answer the question "Why does it work ?"