The PECS teaching protocol is based on B.F. Skinner’s book, Verbal Behaviours, and broad spectrum applied behaviour analysis. Specific prompting and reinforcement strategies that will lead to independent communication are used throughout the protocol. The protocol also includes systematic error correction procedures to promote learning if an error occurs. Verbal prompts are not used, thus building immediate initiation and avoiding prompt dependency.

PECS consists of six phases and begins by teaching an individual to give a single picture of a desired item or action to a “communicative partner” who immediately honours the exchange as a request. The system goes on to teach discrimination of pictures and how to put them together in sentences. In the more advanced phases, individuals are taught to use modifiers, answer questions and comment.

The primary goal of PECS is to teach functional communication. Research has shown that some learners using PECS also develop speech. Others may transition to a speech generating device (SGD). The body of research supporting the effectiveness of PECS as an evidence-based practice is substantial and continues to expand, with more than 190 research articles from all over the world.