The Picture Exchange Communication System (PECS) is described by its authors as "a unique AAC training package developed for use with young children with autism and other social-communication deficits." (Frost & Brody 1994).
Originally devised to teach people with autism the basic concept of communication, the system is built on established psychological principles (ABA – Applied Behaviour Analysis) which include shaping and reinforcement. Trained facilitators gradually shape the individual's impulse to reach for a desired object into the communication act of giving a symbol to another person. That person gives them the desired object in return. People with autism or profound learning difficulties benefit from experiencing communication made concrete in this way.
However, the PECS system is not necessary or appropriate for people who already have the desire and motivation to interact. PECs is a total system for developing full communication in six stages. Unfortunately many people introduced to this system are never moved much beyond this basic stage.
Pyramid Educational Consultants UK Ltd, Website: www.pecs-unitedkingdom.com