A Systematic Review of Acquisition and Mastery of Skills Taught Using the Picture Exchange Communication System

Augmentative and Alternative Communication

Forbes, H. J., Travers, J. C., et al. (2024).

Augmentative and Alternative Communication, 40(2), 100-114.

This systematic review explores the use of Picture Exchange Communication System (PECS) by individuals with developmental disabilities. This review investigates the proportion of individuals who master the various levels of PECS and the number of trials needed to achieve mastery.

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Single-case research designs with symbol exchanges depicted on a time-series graph for each participant

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<div>The following rates of mastery were noted for individuals with developmental disabilities at each level of PECS:</div> <ul> <li><strong>Phase I:</strong> 76% (44/58) of participants mastered Phase I (18 studies). This phase involves exchanging a picture symbol with a communication partner when both are in reach.</li> <li><strong>Phase II:</strong> 70% (39/56) of participants mastered this phase (17 studies). Phase II involves traveling to exchange a picture symbol with a communication partner.</li> <li><strong>Phase IIIa:</strong> 63% (33/52) of&nbsp; participants mastered Phase IIIa (16 studies). This phase involves exchanging a picture symbol of a preferred item when the picture symbol in present in an array of non-preferred distractors.</li> <li><strong>Phase IIIb:</strong> 48% (21/44) of participants mastered this phase (14 studies). Phase IIIb involves exchanging a picture symbol of a preferred item when the picture symbol in present in an array with at least 1 preferred distractor.</li> <li><strong>Phase IV:</strong> 57% (8/14) of participants mastered Phase IV (6 studies). This phase involves exchanging an "I want" picture symbol alongside a preferred item symbol.&nbsp;</li> <li><strong>Phases V and VI:</strong> Only 1 out of 3 participants (33%) mastered these phases. Phase V involves the exchanging of an "I want" picture symbol alongside a preferred item symbol in response to the prompt "What do you want?" Phase VI involves the exchange of the correct picture symbol in response to the prompts "What do you see?", "What do you have?", or "What is it?"</li> </ul> <div>Mastery was generally defined as 80% correct symbol exchanges for two or three sessions; although, some studies had additional requirements (e.g., across different communication partners, across multiple preferred items). On average, participants selected picture symbols from a field of four (range: 1 to 37), with three being the most common array size. <br><br>These findings should be interpreted with caution due to inclusion of approximate results, unclear definitions of mastery, and a lack of experimental controls. Additionally, the findings of this review are limited by strict inclusion criteria that required included studies to clearly demonstrate that their protocols were consistent with the PECS manual. Further research is indicated.</div>

<div>Across studies, when mastery of each level was achieved, it required an average of: </div> <ul> <li><span style="color: #333333;"><strong>Phase I:</strong> 73.8 trials; </span></li> <li><span style="color: #333333;"><strong>Phase II: </strong>73.5 trials; </span></li> <li><span style="color: #333333;"><strong>Phase IIIb:</strong> 56.4 trials; </span></li> <li><span style="color: #333333;"><strong>Phase IV: </strong>122.2 trials; and </span></li> <li><span style="color: #333333;"><strong>Phase V:</strong> 16 trials in one participant.</span></li> </ul> <div>The average number trials to mastery were not reported for Phase IIIa and Phase VI. <span style="color: #333333;">On average, </span>493.9 cumulative trials (range: 167 to 1,485) were required to complete the entire PECS protocol. An average of 37.9 sessions were required to complete all six PECS phases. Authors reported a mean of 16.6 trials per session (range: 10 to 96). <br><br>These findings should be interpreted with caution due to the authors' approximation of results, the wide range of trials between studies, limiting inclusion criteria, unclear definitions of mastery, and a lack of experimental controls. Further research is indicated.</div>

<div>Studies reported that people with multiple developments disabilities generally mastered initial PECS stages. All participants with multiple developmental disabilities mastered:</div> <ul> <li><span style="color: #333333;"><strong>Phase I</strong> (13/13);</span></li> <li><span style="color: #333333;"><strong>Phase IIIa</strong> (9/9); and </span></li> <li><span style="color: #333333;"><strong>Phase IIIb</strong> (4/4).&nbsp;</span></li> </ul> <div><span style="color: #333333;"> Phases IV through VI were targeted for only one participant, who did not master them. This review did not provide the exact values of mastery for Phase II within this population. Additional research is indicated due to an overall paucity of evidence, small sample sizes, and significant potential for bias.&nbsp;</span></div>

<div>Studies reported the following rates of mastery for individuals with developmental delay:</div> <ul> <li><span style="color: #333333;"><strong>Phase II:</strong> 57% (4/7); and</span></li> <li><span style="color: #333333;"><strong>Phases IIIa and IIIb:</strong> 44% (4/9).</span></li> </ul> <div>This review did not provide exact rates of mastery for Phases I, IV, V, or VI within this population. Additional research is indicated due to an overall paucity of evidence, small sample sizes, and significant potential for bias.</div>

<div>Studies reported the following mastery rates for individuals on the autism spectrum:</div> <ul> <li><strong>Phase IIIb:</strong> 52% (11/21); and</li> <li><strong>Phase</strong> <strong>IV: </strong>86% (6/7).&nbsp;</li> </ul> <div>This review did not provide exact rates of mastery for Phases I, II, IIIa, V, or VI for individuals on the autism spectrum. Additional research is indicated due to an overall paucity of evidence, small sample sizes, and significant potential for bias.</div>

<div>Studies reported the following rates of mastery for individuals with intellectual disability:</div> <ul> <li><strong>Phases I through IIIa:</strong> 80% (4/5) of participants;</li> <li><strong>Phases IIIb through VI:</strong> 50% (1/2) of participants;</li> </ul> <div>Additional research is indicated due to an overall paucity of evidence, small sample sizes, and significant potential for bias.</div>