P.E.C.S is a simple, economical, alternative and augmentative communication system by exchanging pictures. It was developed in 1985 and first used in the program of Autism Delaware, for people with autism and related developmental disorders.
The design is such that it enhances / facilitates communication in a variety of environments (home, school, community, etc.), while  can be understood by and carried out by non –trained persons

Based on the principles of behaviorism linking stimulus to response and especially in the book of BF Skinner «Verbal Behavior» (Understanding of Verbal Behavior) .

The training protocol evolves in 6 stages. It  gradually becomes difficult starting with the exchange of single image with partial assistance (prompt) and using verbal factors (verbal operands), having as a goal the development of initiative in communication and ultimately autonomous communication (in complete sentences).

More specifically:

  • In Step 1, the student learns how to communicate by exchanging a picture for an object / activity that the child is  keen in  (reinforcer)
  • In Step 2, the student learns to generalize each new skill using at different distances, with different people and in different places. Also, the student learns to be more persistent in communicating. During the second stage still manages single image.
  • In Step 3, the student learns to select between two or more images (pictures distinction) the object or activity he wishes (reinforcer), while the images are transferred from the table in a communication book
  • In Step 4, the student learns to use simple sentences with the image of the verb “want” and the image of the object / activity that really want (amplifier). At this stage, to work with the structure of the proposal, the student uses a detachable base. He learns to expand his vocabulary and his proposals adding verbs, nouns, adjectives, prepositions, etc.
  • In Step 5, the student learns to use the PECS to answer questions.
  • In Step 6, the student learns to comment when asked “What is it?” “What do you see?” ‘What are you listening? “Etc, introducing proposals in an appropriate manner.