What Is PECS?
The Picture Exchange Communication System (PECS), developed by Andy Bondy and Lori Frost in the 1980s, is a structured augmentative and alternative communication (AAC) program that teaches learners, especially those with autism and limited speech, to communicate by exchanging picture cards with a communication partner. It is designed around behavior analytic principles, including reinforcement, prompting and fading, error correction, and generalization. PECS focuses first on initiation, which makes it distinct from many programs that begin with responding to questions.
Connection to Verbal Behavior
PECS teaches the mand, a verbal operant controlled by a motivating operation and followed by specific reinforcement. The learner approaches a partner and hands over a picture of a desired item, which is a mand for that item. Because the response is controlled by the learner's motivation rather than by verbal stimuli from the partner, it differs from an echoic or a tact. In later phases, the learner is taught to answer questions and to comment, which relates to intraverbal and tact repertoires. On the BCBA exam, be prepared to link PECS to the mand and to explain why teaching manding first is valuable.
Before You Begin: Reinforcer Assessment
Because PECS depends on the learner's motivation, start with a thorough preference assessment to find highly preferred items. Use multiple stimulus without replacement or paired stimulus assessments and observe the learner's behavior during free access. Select items that are reinforcing across the day, including edibles, toys, and activities. Refresh the list frequently since preferences change. Use small portions so the learner can make many exchanges per session.
Roles in Early PECS Training
Phase I requires two trainers:
- Communication partner: Sits across from the learner, holds the reinforcer, and receives the picture.
- Physical prompter: Sits behind the learner and delivers physical prompts to pick up the card, reach, and release the card into the partner's hand.
Using a physical prompter lets the communication partner avoid giving verbal or gestural prompts, which helps prevent prompt dependence. The prompter then fades physical help across trials.
The Six Phases of PECS
Phase I: How to Communicate
The learner learns to pick up a picture of a highly preferred item, reach toward the communication partner, and release the picture into the partner's open hand. The partner immediately says the item name and gives the item. No verbal prompts such as "What do you want?" are used. Physical prompts are faded as quickly as possible. The goal is spontaneous exchanges with different partners and in different settings.
Phase II: Distance and Persistence
The learner learns to travel to the picture, retrieve it, and approach a partner who is at a distance and not necessarily facing the learner. Distance between the learner and the picture, and between the learner and the partner, is gradually increased. This phase teaches persistence, such as getting the partner's attention if the partner does not respond immediately.
Phase III: Picture Discrimination
The learner learns to choose between two or more pictures to request a desired item. Pictures are arranged on a communication book. The learner is first taught to discriminate between a highly preferred item and a nonpreferred one, then between two preferred items. If the learner selects the wrong picture, an error correction procedure is used: the partner provides the item that was requested, shows that it does not match, and the trial is repeated with prompts to ensure the right selection. Learners also learn to find and use the communication book.
Phase IV: Sentence Structure
The learner builds a sentence strip using an "I want" picture and a picture of the item, and hands the strip to the partner. The partner reads the sentence aloud, pointing to each picture. The strip may be expanded to include attributes such as color or size. Phase IV builds structured language and supports vocal approximation if the learner begins to vocalize.
Phase V: Answering "What Do You Want?"
The learner learns to answer the question "What do you want?" by constructing a sentence strip, while still being able to request spontaneously. A time delay procedure is often used: the partner presents the item, waits for the learner to initiate, then asks the question and prompts if needed.
Phase VI: Commenting
The learner learns to comment in response to questions such as "What do you see?" and "What do you hear?" by using the sentence starters "I see," "I hear," and "I feel." This expands the repertoire from mands to tacts. The learner is taught to distinguish between requesting and commenting, which is important for developing social communication.
Key Procedures Within PECS
- No verbal prompts: Verbal prompts are avoided to promote spontaneous initiation and reduce prompt dependency.
- Immediate reinforcement: The learner receives the item right away on every exchange, especially in early phases.
- Systematic prompt fading: Physical prompts are faded using backward chaining of the exchange response.
- Error correction: A four-step process is used for discrimination errors: demonstrate the error, model or prompt the correct response, test again, and return to a reinforced trial.
- Generalization training: Teach across people, places, and items from the start.
- Teaching vocalization: Vocal approximations are reinforced, and the picture exchange remains the primary mode until speech develops.
Frequently Asked Questions
Does PECS Interfere with Speech?
Research does not show that PECS prevents speech. Some studies show that a portion of learners develop speech while using PECS, and many show increased vocalization. The system is designed to promote communication in any form while speech develops.
Which Learners Are Good Candidates?
PECS is often used with learners who have limited functional speech, including those with autism, intellectual disability, and other communication disorders. There are no strict prerequisite skills such as imitation or eye contact.
How Does PECS Compare to Sign Language or SGDs?
Each mode has advantages. Signs require motor imitation skills and communication partners who understand signs. PECS uses pictures that are understandable to most communication partners and requires no physical imitation. Speech-generating devices produce speech and can have large vocabularies but may require more training. Select the mode based on assessment, learner skills, partner needs, and learner preferences. Consider a multimodal system.
Troubleshooting
- Learner does not exchange independently: Check that the reinforcer is highly preferred and that the physical prompter is fading assistance quickly.
- Learner relies on the prompter: Change the prompter, move farther away, and increase the delay before prompts.
- Learner makes frequent discrimination errors: Use more distinct pictures, increase the motivation, and use error correction consistently.
- Learner only requests one item: Expand the list of preferred items and vary the context.
- Cards are lost or destroyed: Use laminated cards with Velcro and keep spares.
Data Collection
Record each trial as independent or prompted, with the type of prompt used, for Phase I. In later phases, record the percentage of independent exchanges, correct discriminations, sentence structure accuracy, and number of spontaneous requests. Use these data to decide when to move to the next phase. The PECS manual includes data sheets and criteria for phase progression.
Training and Fidelity
The Pyramid Approach to Education and the PECS Phases workshop are available to train staff. Implementation fidelity matters, since deviations such as verbal prompting or inconsistent reinforcement can slow progress. Use behavioral skills training to teach new staff and parents, and monitor with a fidelity checklist.
How This Appears on the BCBA Exam
You may be asked to identify the verbal operant taught in Phase I (mand), why verbal prompts are avoided (to prevent prompt dependence and promote initiation), or what a physical prompter does. You may also be asked how to select an AAC modality for a learner or how to describe PECS in terms of behavioral principles. Be prepared to describe how PECS uses prompt fading, reinforcement, and error correction.
Key Takeaways
- PECS teaches spontaneous, learner-initiated communication through picture exchange.
- Phase I uses two trainers, no verbal prompts, and immediate reinforcement.
- Later phases teach discrimination, sentence building, answering questions, and commenting.
- Choose AAC modes based on the learner's skills and needs.