„These authors claimed that children who use 30 to 100 pictures often begin speaking while handing over their selected pictures. They claimed that 30% of users begin to use single word utterances while using PECS, and 59% develop independent speech if training begins before age 5 and continues for at least a year (Bondy&Frost, 1994b)”
Bondy, A. & Frost, L. 1994 b The picture exchange communication system. Focus on Autistic Behavior, 11, 1-19
Źródło: Assessing Topography-Based Versus Stimulus-Selection-Based Verbal Behavior: A Comparison From the Literature” Bloh. Ch., Behavior Analysis: Research and Practice 2016, Vol. 16, No. 1, 16