The Picture Exchange Communication System (PECS; pronounced "pex") is a visually presented method for teaching children with autism spectrum disorder to comprehend language. The PECS method has six sequential and systematic phases. Each one breaks the task of language acquisition into small steps. Each phase must be presented in order. As children master each phase, they are advanced to the next appropriate phase.
The first PECS phase is non-verbal and silent. Therapists physically prompt children to exchange pictures for specific desired objects. The purpose of phase one is simply to help children make a connection between the pictures and the various desired objects. A variety of objects, treats and activities are offered so that the children do not mistakenly learn that the act of exchanging pictures for desired objects or activities is limited to a particular type of object or activity. However, in this first stage, children are not required to learn to distinguish between the different pictures. Once children learn to exchange pictures for objects or activities, they are ready for phase two.
The second phase of PECS is designed to help children understand how to start communication. The therapist introduces a communication board in this phase, which remains non-verbal. Children learn to remove pictures from the communication board and hand them to the therapist to receive their desired object or activity. As this phase continues, the therapist gradually increases the physical distance between him or herself and the students. Because of this increased distance, children learn that they must make a physical effort to get what they desire. They must get up from their seat, go to the communication board, remove the picture, and then walk it over to the therapist to make the exchange. When children have internalized the need to make a physical effort to obtain their reward, they are ready for phase three.
During phase three, children are taught to distinguish between the different pictures. Having learned that pictures can be exchanged for rewards, they now must learn that each picture is associated with a specific reward. To get this lesson across, the therapist presents the children with a picture of a desired object and a picture of an object that the children do not desire. Separately, the trainer also presents both the desired and undesired objects. The pictures are placed on the communication board, and the children are encouraged to start their usual routine of exchanging pictures for rewards. However, unlike in prior phases where children always received rewards, in this phase, they receive the object indicated by the picture, whether they want that object or not. The therapist begins using words during this phase. If the children give the trainer a picture of crayons, the trainer says, "You want crayons", while presenting them with the coloring item. When the children protest, the therapist says, "Ask for treat", to encourage the child to give the appropriate picture. This prompt encourages the children to return to the communications board and actively look at the pictures. Once children can distinguish between a variety of pictures to obtain the rewards that they want, they are ready for phase four.
The fourth phase of PECS involves teaching the basics of sentence structure. Traditionally, the first sentence taught is "I want", because it is very motivating, and it corresponds with the first three phases which are about getting something you want. Without using spoken words, the therapist guides the children to a sentence strip consisting of a picture representing "I want." The children are physically prompted to place a picture of an object that they desire at the end of the sentence strip. The child then exchanges the completed sentence for the desired object.
When children can reliably create and exchange simple sentences for desired objects and activities, therapists begin speaking the sentences out loud. This helps the children make connections between the visual sentences that they have made and the spoken language. For example, the therapist says "I want book" when children hand them a completed sentence strip indicating that they want a book. Children are ready for phase five when they spontaneously complete sentence strips and successfully exchange them for desired objects or activities.
Phase five introduces the phrase, "What do you want?" into the picture exchange. The therapist simply asks the children what they want, and then guides them to the communication board. Once children consistently demonstrate that they know to indicate what they want when asked, they are ready for phase six. Children often master phase five very quickly.
Phase six works to expands on the sentence completion tasks first presented in phase four. Therapists introduce children to new and different phrases such as, "I see toys", or "I like toys", and encourage them to respond. Emotion and attribute descriptors are taught as the process continues. For example, the therapist might encourage children to ask for the yellow pillow or the big stuffed animal. Alternatively, children may be prompted to describe how they feel. Phase six continues in an ongoing and expansive way as long as the picture exchange process continues to be valuable or necessary for facilitating communication.
PECS is a valuable teaching and learning tool. It also may be used to help children transition between activities or tolerate changes in routine. The picture exchange metaphor taught in PECS is also used to help children understand the concept of a schedule. Visual schedules are created by placing pictures representing the day's activities on a communications board or wall area. For this purpose, pictures representing dressing, bathroom time/elimination, eating, therapy, school and countless other activities would be used. Children learn to check their schedules to know what activities will come next.