PECS is a type of augmentative and alternative communication technique that can be part of ABA where individuals with little or no verbal ability learn to communicate using picture cards. Children use these pictures to “vocalize” a desire, observation, or feeling. These pictures can be purchased in a manualized book, or they can be made at home using images from newspapers, magazines or other books. Since some people with autism tend to learn visually, this type of communication technique has been shown to be effective at improving independent communication skills, leading in some cases to gains in spoken language.

A formalized training program is offered through a company called Pyramid Products, and this program takes the caregiver and child through different phases. In ohase one, a communication trainer works with the child and their caregivers to help decide which images would be most motivating. Cards are then created (or provided through a pre-made book) with those images, and the trainer and the caregiver work with the child to help him or her discover that by handing over the card they can get the desired object. In phase two, the caregiver then moves farther away from the child when showing the picture, so that the child must actually come over and hand over the card to receive the food reward. This process engages the child's ability to seek and obtain another person's attention. In this way, a full vocabulary and methods for using these new words are taught to the affected individual.

In later phases, children are given more than one image so that they must decide which to use when requesting an item, and throughout the process the number of cards grows and thus the child's ‘vocabulary' also increases. Over time, the child may develop the ability to use sentences, including phrases like “I want” to start off the sentence, and even use descriptors like “large” or “red”. Throughout the process, which may take weeks, months or years, the caregiver gives constant feedback to the child. It is thought that by allowing children to express themselves non-verbally, the children are less frustrated and non-desirable behavior including tantrums is reduced. 

Studies show that PECS is effective in teaching communications that involve single words or short phrases, and that gains may generalize to everyday settings. Ongoing consultation from an expert in this approach is likely to be necessary to maintain these gains.