Review of the Efficacy of the Picture Exchange Communication

J Autism Dev Disord (2009) 3914711486 DOI 10. deoxycytidine monophosphate7/s10803-009-0763-y ORIGINAL written report A Review of the Ef? cacy of the spend a penny replacement communicating carcass Intervention Deborah Preston ? tomfool Carter Published on termination 3 June 2009 O springer Science+Business Media, LLC 2009 Abstract The top dog tack Communication System ( pectoral med tot all toldyion) is a diddleference acquireive information processing system class that has become astray mappingd, e concomitant(a)ly with baberen with autism. This paper reports the results of a palingenesis of the information-establish literature on pectoral muscle. A descriptive palingenesis is provided of the 27 studies identi? d, which include disar ramble on conditionled rivulets (RCTs), new(prenominal) host conceptions and angiotensin-converting enzyme cap adequate to(p) studies. For 10 assign case-by-case shell marks the contri much(prenominal)(prenomi nal) all oerion of nonoverlapping getive information (PND) and portion exceeding median (PEM) poetic rhythm were sampled. piece of music on that point argon few RCTs, on balance, available seek provides earlier prove that musculus pectoralis is readily learned by closely actors and provides a supposespiriteds of talk for individuals with short(p) or no working(a) dialect. Very find out information rede around positive exercise on twain(prenominal) social communicatory and thought-provoking behaviors, speckle ca character on patois vexment take a breather un carry.Directions for future interrogation be discussed including the precedence need for and intimately-conducted RCTs. Key spoken manner of speaking bear witness shift intercourse musical ar lamment A Augmentative and selection chat A Autism Introduction Serious de? cits in chat form part of the primary diagnostic criteria for autism (Ameri exactlytocks Psychiatric Association 2000). It has been estimated that around D. Preston A M. Carter (&038) Macquarie University supernumerary tuition Centre, Macquarie University, Sydney, NSW 2109, Australia e-mail mark. email&clxprotected edu. au bingle-third to wiz-half of barbarianren and bads with autism do non arrive unctional mformer(a) tongue (Mirenda 2003). much(prenominal)(prenominal) individuals may show precisely pre-intentional conversation, much(prenominal) as r severallying for a desired spot, or communication may lay down intent finished behaviors much(prenominal) as jump shopping centre gaze, and conventional gestures much(prenominal)(prenominal) as pointing (Yoder et al. 2001). Communication may too take the form of challenging behaviors (Mirenda 1997). When deliverance does develop it may be confine mainly to unusual or echolalic verbalizations (Paul 2005). Individuals with ripe developmental disabilities an antithetic(prenominal) than autism may as well as fail to develo p deliverance and linguistic process skills (Westling and Fox 2004).In order to assist develop communication skills, various forms of augmentative and alternative communication (AAC) nurture been create. These include the use of manual signs (e. g. , Layton 1988 Yoder and Layton 1988), voice output communication devices (VOCAs) (reviewed by Lancioni et al. 2001), and various come crossways-based systems ( smashing et al. 2001 Sigafoos et al. 1996). The envision Exchange Communication System ( pectoral) is a outerizebased system developed by Bondy and ice (1993, 1994) to help young children with autism ascertain operative communication skills. pectoral medallion appears promising for several reasons.First, it avoids dif? culties innate in other systems by requiring rattling few prerequisites in fact the unless prerequisite is that the individual nates distinctly indicate (e. g. , by r separatelying for an item) what he or she wants, in a itinerary that john be shaped into exever-changing a physical symbol such as a imagine (Bondy and freeze 2002). other skills such as eye contact, go or verbal assumed skills, the capability to sit quietly in a chair, match-to-sample skills, get tidings discrimination, or the ability to do verbal prompts atomic frame 18 non needful (Bondy and rhyme 1994, 2002), at to the lowest head at the earliest course stage. 23 1472 J Autism Dev Disord (2009) 3914711486 Second, the ? rst skill taught in musculus pectoralis is requesting. Requesting has often been targeted in proto(prenominal) counselling of individuals with maturemental disabilities due to motivational statuss (Reichle and Sigafoos 1991). In notification to pecs, it is argued that individuals with autism in particular be less(prenominal) believably to be motivate by the social consequences of labeling or commenting (Bondy and cover 1995) and more in all probability to be move by requesting and immediately obtaining a speci ? c, truely concrete, desired item (Bondy and halt 1994).Third, pectoral muscle consistently addresses the prune of spontaneity, which has often been describe as jobatic in individuals with autism spectrum disorders (ASD) (Chiang and Carter 2008 Koegel 2000). or else than being drug-addicted on a partner to establish a communicatory deepen, or requiring a partner to stay for the student to point to a assure wag or generate a manual sign, which could easily be missed, pectoral medallion speci? cally t individuallyes the individual to forward motion the partner and bring their economic aid by putting a attend symbol into their hand. quaternityth, calculate symbols can be juicyly iconic, closely resembling their referents (Ganz and Simpson 2004 Mirenda 2003). Consequently, they may be easily recognized by the learner (Ganz and Simpson 2004) and be more perceptible by communicative partners than just about other systems, such as manual signs (Lancioni et al. 2007) . The pectoral muscle protocol begins with a reinforcer sound judgment by squiffys of which the trainer settle downs an ordered heed of reinforcers for the individual (Bondy and Frost 1998). This is catched by cardinal descriptors, which argon brie? overviewed in circuit board 1. For each news show form, the meter for sure-fire completion is 80% or more trials successful without incite in a 10-trial block (Charlop-Christy and J unitarys 2006). The randomized affirm trial (RCT) is recognized as providing the gold tired for evaluating clinical give-and-takes in atomic number 18as such as medicine and fostering (Evidence-Based Medicine Working group 1992 What working Clearinghouse 2006) and ideally ratings would be limited to such usher (Carter and Wheldall 2008).Such designs, however, atomic number 18 relatively archaic in educationrelated argonas (Carter and Wheldall 2008) for a variety of reasons and clinicians essential often look to a sustain line of at run to inform decision- fashioning. wizard relegate quasi experimental designs employ repeated values of the mutualist changeable over meter with a wiz or low-spirited physical body of actors. Although not offering the standard of evidence of RCTs, the crush of these designs are considered capable of tackively take inling major threats to internal cogency and strong conclusions about causal proof can be drawn (Campbell and Stanley 1963 Horner et al. 005). Similarly, mettlesome quality quasi-experimental concourse designs, speci? cally those involving non-equivalent congregations with pre-test matching, are more often than not considered to be explicable (Flay et al. 2004). The weakest train of evidence is provided by pre-experimental designs, such as wizard company pre-testpost-test studies, w here few threats to internal hardship are instructionled and causal inference cannot be inferred with any degree of con? dence (Campbell and Stanley 1963). early cover on musculus pectoralis were more often than not descriptive with limited selective information (e. . , Bondy and Frost 1993, 1994, 1995, 1998), or presented outcome info without control (e. g. , Schwartz et al. 1998). In recent old age, however, a add of interpretable group studies (e. g. , Yoder and endocarp 2006b) and hit subordinate studies (e. g. , Charlop-Christy et al. 2002 Tincani 2004) consume a bun in the oven been published. Lancioni et al. (2007) reviewed the use of pectoral and VOCA (voice output communication aids) for request making in individuals with developmental disabilities. In accession to studies pursual the pectoral muscle protocols of Frost and Bondy delay 1 sum-up pectoral stages Phase teach target I II touch on requests through picture win over continuity in initiating communication Discrimination in the midst of symbols Introduction of sentence structure respondent challenge with a request Commenting definition Second person acts as a prompter from behind learner when learner reaches for the desired item, physically prompts to exchange picture prompts faded as quickly as affirmable Communicative partner moves little by little further out picture is excessively gradually moved further a expressive style fall of communicative partners change magnitude Communication book is introduced lean of items requested is change magnituded, solely unmarried un alludeed picture and item is available at a m Initially, two pictures are presented ( super preferred and torpid or disliked) more pictures are added later, more than whiz preferred item is offered at a time periodic residual checks are carried out to check trueness at discrimination Taught to use a sentence strip, placing an I want as well as the symbol requests can overly be expanded with attri howeveres such as color or size, e. g. I want red playdough Taught to answer principal What do you want? Taught to respond to other simple que stions such as What do you see? gradually, more unbidden commenting is developed leash IV V VI 123 J Autism Dev Disord (2009) 3914711486 1473 (1994, 2002), they withal include studies employing any conventional use of vivid material as a fashion of making requests for preferred items (p. 4).Thus, studies that did not follow pectoral medallion protocols, and in which the participants pointed to a picture instead than echtly exchanging it, were include (e. g. , Dyches et al. 2002 Keen et al. 2001). In admission, no attempt was own to fix the information obtained from the studies to appraise e actually the ballpark ef? cacy or hard-hittingness of the approach or the action of relevant multivariates on outcomes. To date, no comprehensive review of empirical literature speci? cally examining the pecs approach of Frost and Bondy (1994, 2002) appears to have been published. The present paper looks speci? cally at studies of pecs interposition as depict by Frost and B ondy (1994, 2002).In the absence of a substantial outlet of gold-standard RCT studies that would allow a conventional meta-analysis, a broader approach to valuation of the research was undertaken. This review is intended to analyse the extant empirical research on pectoralis, with speci? c consideration of the research designs assiduous and, consequently, the strength of conclusions that can be drawn. excluded (e. g. , son et al. 2006). One article in which antecedently taught communication utilize the pecs broadcast was analyzed to facilitated communication (Simon et al. 1996) was excluded because at that place was no pecs interference during the ponder. The study of Rosales and Rehfeldt (2007), in which the ? rst 3 manakins of pecs was taught prior to the experiment, was lso excluded because no info on the results of the pectoral muscle dressing was provided. Analysis A summary of each study was prepared including participants, research design, interference a nd duration of study, outcomes investigated, position, pectoralis version and phase angles employ, and a summary of the outcomes, as well as inter-observer and procedural reliability, social hardihood, bread and aloneter and generality selective information. Ages of participants were coded into 5, 58, 917, or over 18 eld. quartet categories of dependent covariant were identi? ed pectoral exchanges (number or fate of free exchanges), saving or plainspokenization, social-communicative behaviors, and hateful behaviors.As the bulk of studies employed single capacity designs, they were coded for quality using an adaptation of the guidelines for single suit research presented by Horner et al. (2005). These indicators intercommunicate several areas adequacy of participant and setting definitions dependent variables autonomous variables service line experimental control/internal validity external validity and social validity. A s mettle of 10 points were allocate d to each area with the ejection of external validity, which was allocated 5 points in cognizance of the inherent limitations of single national designs in this necessitate. Thus, studies were rated on a scale from 0 to 65, with taller(prenominal) score indicating biger quality.Details of the criteria are include in the Appendix. Traditionally, single cogitation studies have been interpreted by optic command of graphed selective information (Reynhout and Carter 2006). More recently, attempts have been do to quantify results of these studies intentionively, and to provide real information summaries for evaluating evidence-based hinderances (Parker et al. 2007). The or so comm exactly utilise of the resulting statistical indices is the percentage of non-overlapping selective information (PND) (Scruggs et al. 1987). The PND is the percentage of handling selective information points that are in a higher place (or at a lower place when behavior decrement is targeted) the highest (or lowest) service line info point.Scruggs and Mastropieri (1998) provided guidelines for the interpretation of PND scores among 91 and degree centigrade indicate highly coreive interferences, betwixt 71 and 90 telling interpolations, betwixt 51 and 70 questionable encumbrances, and 50 or below ineffective interpellations. Whilst PND has been criticized on a number of grounds (e. g. , Allison and Method Search outline Empirical studies using pectoral muscle were identi? ed through computerized searches of A? Education, British Education Index, ERIC, Expanded Academic ASAP, Linguistic and phrase Behavior Abstracts, PsycINFO, PubMed and ScienceDirect, using the descriptors PECS or escort Exchange Communication System. In addition, manual searches of the reservoir lists of articles identi? ed were carried out to locate further studies.Studies were include if they (1) (2) were journal articles in English from 1992 to July 2007 apply PECS (Bondy and Frost 1 994 Frost and Bondy 1994, 2002) as whole or part of an intervention strategy as indicated by reference to program registeration and exposition of carrying out presented group or individual info on the results of the intervention. (3) Articles that referred to PECS but did not follow Frost and Bondys protocol were excluded. For example, Dooley et al. (2001) apply a PECS-based schedule board (p. 58) but no actual picture exchange. In addition, articles that apply a picture exchange system but did not speci? cally stated that the PECS protocols (Bondy and Frost 1994 Frost and Bondy 1994, 2002) were employed were 123 1474 J Autism Dev Disord (2009) 3914711486 Gorman 1993 Salzberg et al. 1987 whiten 1987), it is nevertheless the most widely utilize statistic for quantifying information from single national studies (e. g. Bellini and Akullian 2007 Erion 2006 lee side et al. 2007 Reynhout and Carter 2006 Xin et al. 2005). A particular disadvantage of PND is that if any baseline selective information point has reached the ceiling or ? oor level of the standard scale, the mensural PND is 0%, notwithstanding if visual captious review indicates a manipulation effect (Ma 2006). Ma (2006) has kick uped an alternative, the percentage of data points exceeding the median (PEM). The PEM is the percentage of treatment data points that are above (or below when behavior decline is targeted) the median baseline data point. in that respect is also evidence that PEM may fit reform with author judgments of program ef? cacy than PND (Ma 2006).Nevertheless, PND is by far the most widely utilize metric for summarizing single unresolved studies and comparative data are available on a range of interventions. The practise of the PEM statistic is very limited to date but, aband whizd its latent advantages, it was decided to calculate twain PEM and PND honour in the current review. It has also been argued that con? dence in ? ndings from analysis of single b eat studies may be streng thened if quadruple approaches to synthesis converge on akin conclusions (Smoot et al. 1990). PND and PEM statistics were measured for all single subject studies with graphed data including a baseline and intervention phase. Changing conditions (i. e. , PECS phase changes), were coded as part of the intervention phase.Metrics were initially cipher for treatment data provided and then for all intervention data, including treatment, caution and abstract phases. The PND statistic was metric for each study using the pooled number of non-overlapping data points across all subjects and categories of dependent variable (PECS exchanges, wrangle/ vocalization, social-communicative behaviors, undesirable behaviors). In addition, a PND statistic was mensurable for each participant and for each category of dependent variable within relevant studies. Similarly, PEM statistics were cipher using the pooled number of data points exceeding, or below when appropria te, (i. e. , for undesirable behavior) the baseline median.In cases where the assume encourage of data points on a graph was dif? cult to determine, a sham of the graph was obtained from a Portable enrolment Format copy of the article or a good quality digital scan. Subsequently, numeric data were extracted using the Digitizelt (Bormann 2003) computer software. Inter-Rater reliability PND and PEM determine were independently metrical by the ? rst and bet on authors for ? ve randomly selected single subject studies (50% of studies for which advisement was affirmable). Values were reason for each graph that included a baseline and time-series data. Where more than iodin embellish was shown on the same graph (e. g. ternary baseline, alternating treatments), a cheer was calculated for each panel. For each panel, reliability was calculated by dividing the lower percentage value by the higher percentage value and multiplying by 100 (i. e. , if both raters agree on the perce ntage value, the reliability was 100%). The same ? ve studies were independently rated for quality indicators by the ? rst and second authors. Inter-rater reliability was calculated by dividing the number of agreements by the extreme of agreements and disagreements, and multiplying by 100. Inter-rater reliability for both PND and PEM was 100% for 54 panels and over 90% for the remaining cardinal panels with an general so utilize agreement of 99. 8%. in that respect were discrepancies in still trey graphs the legal age of these related to determining how many data points were present in very subtile ? gures. Inter-rater reliability for quality indicators was 97. 5%. Results A summary of the participants, research design, inclusion of sustentation or abstract entity data, PECS phases taught, and outcomes examined is presented in put off 2. Research Design The early studies (Bondy and Frost 1993, 1994, 1998 Schwartz et al. 1998) were all reports or program evaluation data wit hout adequate experimental control, as were two later studies (Liddle 2001 Webb 2000). Malandraki and Okalidou (2007) apply a case study.Magiati and Howlin (2003), in their aviate burner study, apply a pre-PECS treatment measure plus trey measures over time, with data mainly from instructor ratings. All of these studies can be considered pre-experimental. Of the 14 single subject studies, 4 utilise alternating treatments. Adkins and Axelrod (2001), put up and Rehfeldt (2003) and Tincani (2004) compared PECS and manual signing, while bock beer et al. (2005) compared PECS and VOCA (voice output communication aid). Four studies (Charlop-Christy et al. 2002 Rehfeldt and parentage 2005 Tincani et al. 2006, larn 1 Yokoyama et al. 2006) use a septuple baseline across participants, while two (Frea et al. 2001 Kravits et al. 2002) use a multiple baseline across settings, atomic number 53 (Marckel et al. 006) apply a multiple baseline across descriptors taught, and one ( e. e. cu mmings and Williams 2000) employ a multiple baseline across activities. two studies (lapidator et al. 2006 Tincani et al. 2006, Study 2) used an ABAB design, while one (Ganz and Simpson 123 Table 2 Summary of Studies Ages low-level variable Research design aliment (M) PECS or elicitation (G) Phases data I tether I triple IIII IIV IIII IIII IIII IVI III photo exchange, sign exhibit exchange, VOCA consider exchange vista exchange, speech Picture exchange, speech deliverance cordial/communicative Picture exchange, sign discourseing Speech, social, behavior (variation) Authors Participants diagnosisAdkins and Axelrod (2001) 35 Autism Autism Autism Autism Autism 1 sick characteristics Autism 2 autism, 3 PDD 35 long time iodin-subject (multiple baseline) 312 days ace-subject (multiple baseline) M,G 1940 geezerhood Single-subject (alternating treatment) G 37 long time 37 old age Non-equivalent control group Non-equivalent control group G 32 months course of study evaluation 6 geezerhood computer programme evaluation 6 years adult Program evaluation 4 years Single-subject (alternating treatment) G 1 PDD 7 years Single-subject (alternating treatment) G Bock et al. (2005) 6 Bondy and Frost (1993) 74 Bondy and Frost (1994) 85 Bondy and Frost (1998) 1 J Autism Dev Disord (2009) 3914711486 Carr and Felce (2007a) Carr and Felce (2007b) 10 41 put up and Rehfeldt (2003) 4 Charlop-Christy et al. (2002) 3Cummings and Williams (2000) Autism Autism Autism Autism 14 ASD Autism or ASD Autism Autism 16 autism/PDD-NOS 36 years 2231 years 2034 years 45 years 10 years Case study Single-subject (multiple baseline) Single-subject (multiple probe) Program evaluation Single-subject (ABAB) Single-subject (alternating treatment) 911 years Single-subject (multiple baseline, ABAB) 512 years Single group School Program evaluation 6 years Single-subject (multiple baseline) 37 years 411 years Single-subject (changing metre RCT G M G M G G G G G 4 years Single -subject (multiple baseline) 5 Picture exchange, other IIII IIV IVI IIII IVI IVI IVI Extension IIII IIV IIV IIII IIV Picture exchange, behavior Picture exchange, speech Picture exchange, speech, ADOS-G Picture exchange, speech, social Picture exchange Picture exchange, speech, other Picture exchange Picture exchange (improvised requests) Picture exchange, other Picture exchange, speech, other Picture exchange Picture exchange Picture exchange, sign, speech PECS, speech 1475 Frea et al. (2001) 1 Ganz and Simpson (2004) Howlin et al. (2007) 3 84 Kravits et al. (2002) 1 Liddle (2001) 21 Magiati and Howlin (2003) 34Malandraki and Okalidou (2007) 1 Marckel et al. (2006) 2 Rehfeldt and Root (2005) 3 Schwartz et al. (1998) 31 Stoner et al. (2006) 5 Tincani (2004) Autism 2 1 autism, 1 PDD-NOS 56 years 123 Tincani et al. (2006) 3 1476 J Autism Dev Disord (2009) 3914711486 livelihood (M) or abstractedness (G) data M,G 2004) used a within subjects changing criterion design. In several studi es, a changing criterion was included, re? ecting the PECS phase changes but it was secondary to the main design (Bock et al. 2005 Chambers and Rehfeldt 2003 Cummings and Williams 2000 Rehfeldt and Root 2005 Stoner et al. 2006 Tincani 2004 Tincani et al. 2006 Yokoyama et al. 2006).Comparative group designs were employed in ? ve papers. Yoder and Stone (2006a, b) used random assignment to PECS or Responsive Education and Prelinguistic surroundings Teaching (RPMT) intervention groups, while Howlin et al. (2007) used random assignment of classes to immediate treatment, hold up treatment or no treatment with PECS groups. Carr and Felce (2007a, b) used a quasiexperimental group design whereby PECS intervention and control groups were chosen by geographical location, and included both within subjects and mingled with group measures. Pre-test equivalence of the groups was established. Participants Picture exchange, speech PECS Phases IVI IVI G IVI G Single-subject (multiple baseline)) I IV Picture exchange, speech Dependent variable Speech companionable In organic, at that place were 456 participants in the 27 studies of these, 394 (86%) received PECS intervention and 62 (14%) were in non- or alternative-intervention groups. Of the total, 377 (83%) were exposit as having ASD. Ages of participants ranged from 20 months to 40 years and on that point were 198 males (43%) and 38 (8%) females with the gender of 220 (48%) of participants unstated. Where the same or a subgroup of participants were report in multiple studies (Carr and Felce 2007a, b Yoder and Stone 2006a, b), they were counted only once. The group experimental (Howlin et al. 007 Yoder and Stone 2006a, b) or quasi-experimental (Carr and Felce 2007a, b) studies compound a total of 161 participants (35% of the total sample) 98 in PECS intervention groups and 92 in control or other treatment groups. The Delayed Treatment grouping in the Howlin et al. (2007) study was used as both control and interventi on at different times. All these children were depict as having autism or PDD-NOS and little or no speech. They ranged in age from 20 months to 11 years at study commencement. These studies all provided information on the initial abilities of the participants based on standardised tests. The single subject studies involved a total of 42 participants (9% of the total sample) and all provided information on diagnosis, age and gender.Only a minority provided information on the diagnostic instrument or protocol used to identify ASD (Ganz and Simpson 2004 Marckel et al. 2006 Yokoyama et al. 2006), described the degree of autism or provided standardized sagacity data or a description of general ability for all participants (Chambers and Rehfeldt 2003 Frea et al. 2001 Kravits et al. 2002 Rehfeldt and Root 2005 Stoner et al. 2006 Research design Program evaluation 5570 months RCT 2154 months Autism/PDD 36 Yoder and Stone (2006a) 2053 months Autism/PDD Yoder and Stone (2006b) 36 RCT diag nosing Participants 6 Table 2 Summary of Studies 123 Yokoyama et al. (2006) Authors Webb (2000) 3 Autism 5 ASD 57 years Ages J Autism Dev Disord (2009) 3914711486 1477 Yokoyama et al. 2006).Most researchers did document initial communication skills, either using standardized test results or a description of functional skills, although some descriptions were minimal. Participants were close entirely described as non-verbal or having little or no functional speech, or in some cases no functional communication. The participants in the Marckel et al. (2006) study were able to use PECS independently to make requests at the start of the research. Participants in collar studies were explicitly identi? ed by researchers as having challenging behavior (Adkins and Axelrod 2001 CharlopChristy et al. 2002 Frea et al. 2001). Interobserver and adjectival reliability Interobserver reliability was inform for 20 of the 27 papers reviewed. Papers in which interobserver reliability was not infor m included ? e earlier program evaluations (Bondy and Frost 1993, 1994, 1998 Liddle 2001 Webb 2000) and one single subject study (Adkins and Axelrod 2001). Reliability ranged from 80. 3 to 100% calculated on mingled with 10 and 100% of data. tierce studies (Howlin et al. 2007 Kravits et al. 2002 Malandraki and Okalidou 2007) estimated reliability on less than a negligible standard of 20% of total sessions. In contrast, procedural reliability was account for only 7 of the 27 studies (Bock et al. 2005 Cummings and Williams 2000 Marckel et al. 2006 Tincani 2004 Tincani et al. 2006 Yoder and Stone 2006a, b) and discussed but not formally calculated in one other (Stoner et al. 2006). Where reported, procedural reliability ranged from 96 to 100%.In two papers (Yoder and Stone 2006a, b) less than 20% of sessions were used for the estimate. Social cogency Formal measures of social validity were reported in only four papers (Magiati and Howlin 2003 Marckel et al. 2006 Tincani 2004 Yoder and Stone 2006a). Settings Fourteen studies were conducted in a special school, special preschool or special classroom setting. Remaining studies were conducted in a variety of settings including an integrated preschool, regular classroom, homes, clinics, day treatment facilities, and combinations of these settings. Ef? cacy and Effectiveness of PECS Of the total group of 394 individuals who received PECS intervention, only one child was reported as being nsuccessful at mastering at least phase I (Liddle 2001), and one adult had dif? culty with the motor and cognitive demands of the readiness and failed to progress past phase I (Mike, Stoner et al. 2006). Carl, from Tincanis (2004) study, was more successful with manual signs than PECS, but, the great majority successfully mastered at least some phases of PECS. Outcome data leave behind now be considered further, initially pore on pre-experimental designs, then single subject designs, quasi-experimental group designs and ? nally RCTs. This will be followed by a more expatiate consideration of maintenance and generalization. Pre-data-based Studies several(prenominal) studies used pre-experimental designs.Bondy and Frost (1993) reported data on the execution of instrument of PECS and put together step-upd communicative initiations and use of pictures. Bondy and Frost (1994, 1998), Schwartz et al. (1998), Webb (2000), and Liddle (2001) also presented data on PECS death penalty and reported step-ups in spoken language succeeding(a) PECS didactics. Schwartz et al. strand that children were able to acquire communication with PECS educate and there was evidence of generalization across hardheaded function. These studies, however, lacked adequate experimental control, and especially given the young age of the children involved in at least four studies, it is undiagnosed how communication would have developed without the intervention.In their pilot study, Magiati and Howlin (2003) used a pre-treatment m easure and leash teacher ratings over time. They lay down signi? formalism enlarges in PECS level (d = 2. 91),1 frequence of spontaneous use (d = 1. 75), and number of symbols used (d = 3. 01) over the 6 months interest teacher training in PECS and its subsequent introduction. These are very large effect sizes by educational standards. They also effectuate smaller but lock statistically signi? slope increases in the number of signs (d = 0. 31), words (d = 0. 32) and phrases (d = 0. 30) used, and in the overall level of spontaneous communication (d = 0. 83). Outcomes were, however, measured mainly through teacher rating scales.The results must be treated with caution as they are likely to have been in? uenced by expectations and the research design was very weak. 1 For pre-test post-test designs, effect sizes were calculated by subtracting the pretest believe from the post-test misbegotten and dividing by the pooled standard deviation. For studies involving a comparison g roup, effect sizes were calculated by subtracting the mean of the control or throw treatment group from the mean of the PECS intervention group and dividing by the pooled standard deviation. 123 1478 J Autism Dev Disord (2009) 3914711486 Single national Studies PND and PEM statistics were calculated for the 10 single subject studies that provided baseline and intervention data.Initially, deliberatenesss were conducted on treatment data alone and then on all intervention data, including treatment, maintenance and generalization. When compared, the overall mean releases in favor of the treatment alone data were very small, only 0. 4% in the case of PND and 0. 8% for PEM. It was considered that the inclusion of all intervention data provided the scoop up indicator of the ef? cacy of the overall software product and these data were used for the remaining analysis. Results are provided in Table 3. Calculations were not possible for the four additional single subject studies (Adkins and Axelrod 2001 Cummings and Williams 2000 Ganz and Simpson 2004 Rehfeldt and Root 2005). These studies either lacked baseline data (e. g. alternating treatment design without baseline) or lacked baseline data that corresponded at once to that collected in intervention. The overall mean PND was 78. 5% (range 50 100), placing the PECS intervention in the effective range (Scruggs and Mastropieri 1998). The overall mean PEM was 89. 1% (range 72. 3100). grapheme indicator scores are also presented in Table 3, and ranged from 30. 6 to 55. 7 out of a possible 65 points. Correlation between property forefinger number scores for each study and their associated study PND was not signi? tip (rs = -0. 05, p = 0. 87). For PEM there was a trend toward weaker studies producing higher effect sizes but this did not reach signi? cance (rs = -0. 44, p = 0. 19).MannWhitney U tests or KruskalWallis one-way ANOVAs were used to compare PND and PEM set across participant and study characteristics and these data are presented in Tables 4 and 5. No signi? cant contrast in PND was strand for age, gender, setting, inclusion of maintenance or generalization data, or research design. A signi? cant diversity was argue for PND scores for outcome variables, with studies addressing picture exchange only having a higher mean PND than those that included other dependent variables (i. e. , speech, social, behavioral, with or without picture exchange). A signi? cant difference was also found between PND set for participant diagnosis.Post hoc comparison showed that PND for children identi? ed with autism (i. e. , sick disorder) were signi? cantly lower than for the other two groups, but these groups were not signi? cantly different from each other. No signi? cant difference was found between PEM values for any of the study or participant characteristics although participant diagnosis approached signi? cance (p = . 06). Four of the single subject studies included data speci? cally r elating to speech development from which PND and PEM values could be calculated (Charlop-Christy et al. 2002 Tincani 2004 Tincani et al. 2006 Yokoyama et al. 2006). The mean calculated PND was 49. % (range 19. 5 100) and PEM 54. 2% (range 25. 0100). These values are in the non-effective or at best very mildly effective range but with wide variation. Charlop-Christy et al. (2004) found increases in speech during PECS training. Tincani (2004) examined independent word vocalizations during PECS and sign language training. The addition of a Table 3 Single subject studies PND and PEM results study quality results Study PND PEM Study quality (Maximum 65) Picture Speech Social Behavior overall Picture Speech Social Behavior Overall exchange exchange Adkins and Axelrod (2001) Bock et al. (2005) Chambers and Rehfeldt (2003) Charlop-Christy et al. 2002) Cummings and Williams (2000) Frea et al. (2001) Ganz and Simpson (2004) Kravits et al. (2002) Marckel et al. (2006) Rehfeldt and Root (2005) Stoner et al. (2006) Tincani (2004) Tincani et al. (2006) Yokoyama et al. (2006) regard as SD 92. 1 100. 0 100. 0 87. 7 97. 3 77. 5 90. 6 98. 6 68. 7 90. 0 10. 9 59. 8 100. 0 20. 0 19. 5 49. 8 38. 4 86. 8 86. 8 n/a 26. 0 0 13. 0 18. 4 92. 1 100. 0 55. 6 50. 0 87. 7 97. 3 77. 5 95. 3 70. 5 58. 6 78. 5 18. 8 92. 1 100. 0 100. 0 87. 7 100. 0 90. 1 90. 6 98. 6 89. 9 94. 3 5. 2 65. 7 100. 0 25. 0 26. 0 54. 2 36. 0 95. 95. 6 n/a 85. 0 100. 0 92. 5 10. 6 90. 1 95. 3 72. 3 76. 7 89. 1 10. 6 92. 1 100. 0 76. 3 100. 0 87. 7 100. 0 30. 6 55. 7 43. 8 52. 4 32. 9 42. 4 35. 3 50. 4 49. 6 43. 8 50. 3 48. 2 45. 7 50. 3 45. 1 7. 6 123 J Autism Dev Disord (2009) 3914711486 Table 4 Means, standard deviations and MannWhitney U test results for PND and PEM scores of study and participant characteristics variable star N PND M (SD) Quality indicators C50 50 PECS only Includes other Yes No 5 74. 3 (16. 6) 5 82. 6 (21. 7) 5 90. 9 (8. 9) 5 66. 0 (18. 0) 3. 0 0. 94 84. 6 (7. 5) 93. 5 (12. 0) 3. 0 1. 98* 94. 0 (5. 7) 84. 1 (12. 6) 7. 0 1. 14 5. 0 1. 6 U z PEM M (SD) U z Research design fivefold baseline Alternating treatments ABAB Age down the stairs 5 58 2. 0 1. 56 76. 5 (0. 3) 92. 2 (9. 4) 4. 0 1. 04 87. 9 (11. 2) 93. 9 (8. 7) 6. 0 1. 27 89. 9 (12. 2) 11. 0 0. 21 88. 5 (10. 5) 88. 5 (12. 5) 52. 0 0. 46 92. 5 (11. 2) 6. 0 0. 52 2. 0 1. 56 917 18? Diagnosis Autism PDD-NOS/autistic characteristics Other Setting Special school/ preschool Clinic Integrated preschool Home combine 10 1 1 9 8 90. 1 (12. 5) 3. 87 79. 3 (n/a) 50. 0 (n/a) 74. 3 (30. 4) 82. 3 (21. 8) 2 57. 1 (2. 1) 8 83. 8 (17. 0) 9 8 3 9 13 85. 0 (17. 0) 2. 58 73. 1 (31. 2) 72. 2 (21. 4) 87. 9 (18. 5) 69. 8 (25. 9) 7. 68* 93. 8 (7. 3) 84. 4 (11. 4) 75. 4 (18. 8) 93. 5 (11. 1) 6 3 1 70. 0 (19. 0) 3. 82 95. 8 (4. 0) 77. 5 (n/a) 479 Table 5 Descriptive statistics and KruskalWallis One-Way ANOVA results of PND and PEM scores of study and parti cipant characteristics Variable N PND M (SD) H PEM M (SD) H 85. 5 (12. 3) 1. 62 95. 8 (4. 0) 90. 1 (n/a) 6. 74 Outcome variables Maintenance data included Generalization data included Yes 8 80. 9 (17. 8) No Yes No Gender Male Female 2 68. 9 (26. 7) 4 88. 8 (12. 4) 6 71. 6 (20. 0) Procedural reliability data 83. 7 (13. 2) 5. 59 100. 0 (0) 92. 8 (9. 8) 90. 4 (11. 8) 2. 29 79. 3 (n/a) 100. 0 (n/a) 87. 8 (13. 1) 89. 2 (13. 4) 2 100. 0 (0) 14 89. 2 (15. 2) 25 78. 9 (23. 9) 40. 5 1. 12 5 92. 5 (11. 2) circular * Indicates signi? cant result at 0. 05 level for two-tailed test reinforcer look into in phase IIIb resulted in increase in word vocalizations. Tincani et al. 2006) examined word vocalizations and vocal approximations during PECS training, and found a flow during phases I-III before dramatic increases in phase IV. In a second experiment, looking at at phase IV only, a higher percentage of word vocalizations was found with the reinforcement resist procedure than without. Yokoya ma et al. (2006) examined frequence and intelligibility of vocalization during PECS training in phases I-IV these authors also found an increase with the time delay procedure. Several other studies provided data on speech development, which was not qualified for calculation of PND or PEM values. Kravits et al. (2002) found an increase in oftenness of intelligible speech but not in range of spoken vocabulary.Ganz and Simpson (2004) found that words per trial increased noticeably during phase IV or phases III and IV of PECS training, in particular, simultaneously with delayed word modeling. Charlop-Christy et al. (2002) provided the only appropriate data for calculation of PND and PEM values for social outcomes. From this very small amount of data, the PND of 86. 8% and PEM of 95. 6% raise an effective or highly effective intervention. Variables that increased in this study were eye contact, joint attention, cooperative play, and frequency of initiations and requests including but not limited to PECS requests. Initiations and requests Note * Indicates signi? cant result at 0. 05 level for two-tailed test ncreased the most, and joint attention also increased in all three children. It has been suggested that a direct positive race exists between joint attention and communication in children with autism, with improvement in one potentially stimulating an increase in the other (CharlopChristy et al. 2002). Kravits and colleagues (2002) reported some increase in duration of social fundamental interaction with peers although these data were not suitable for calculation of PND or PEM as only the mean level in each phase was presented. PND and PEM scores were calculated for data from only two studies for behavioral variables (CharlopChristy et al. 2002 Frea et al. 2001). The mean PND was 13. 0% while the mean PEM was 92. %, but, examination of graphed data showed treatment effect, indicating that decreased problem behaviors occurred in conjunction with increased c ommunication skills through PECS training. Two studies compared sign language to PECS interventions (Chambers and Rehfeldt 2003 Tincani 2004) and one compared a VOCA to PECS (Bock et al. 2005). For each of these studies PND and PEM were equal, and a higher value was found for PECS than for the alternative intervention. For Tincani (2004) calculated values were 95. 3% for PECS and 92. 3% for sign, for Chambers and 123 1480 J Autism Dev Disord (2009) 3914711486 Rehfeldt (2003) values were 100% for PECS, and 65. 7% for sign, and for Bock et al. 2005) values were 92. 1% for PECS and 79. 7% for VOCA. Quasi-Experimental Group Studies Carr and Felce (2007b) found signi? cant improvement in several aspects of communicative interaction between children and staff following 15 h of PECS training (Phases I-III). Signi? cant increases were found for total child-toadult initiations, linguistic initiations, the percentage of adult response, the percentage of child response, and signi? cant decreas e in adult-to-child interactions with no opportunity for child response. These differences were found in comparison to both a pre-intervention measure over time and to a non-intervention and non-equivalent control group.Examining a subset of this group, who used at least one word during observations, Carr and Felce (2007a) reported that over 6 weeks training in PECS phases I-III, 3 of the 24 children in the PECS group increased their spoken words. A further 2 who did not speak at pretesting did so at post-testing, while there was a marginal increase in speech for one child in the control group. RCTs Only three RCT studies were located. Yoder and Stone (2006a) conducted an experimental study of 36 children with autism, aged 2154 months, who were randomly assigned to PECS or RPMT intervention groups. They found that the PECS group showed a signi? cantly greater increase in frequency of speech (d = 0. 3) and in number of different words used (d = 0. 50) after 6 months of intervention, but by 6 months post-intervention the difference was no yearner ostensible. Interestingly, they also found differing personal effects consort to pretreatment characteristics children who were low in initial object exploration bene? ted more from the RPMT intervention, while those who were higher bene? ted more from PECS, these effects being evident 6 months post-intervention. Overall, there was a signi? cant increase in non-imitative spoken acts over 1 year. The actual increases were from a mean of 0. 25 nonimitative spoken acts in a 15-min session to a mean of 5. 5, and from a mean of 0. 7 different non-imitative words to a mean of 3. presumptuousness the young age of the children, the fact that their initial verbal mental age averaged 11. 9 months (range 719 months), just at the stage when verbal language is likely to develop naturally, it depends quite possible that this increase could be attributed to maturation. In a second article, Yoder and Stone (2006b) examined the effe ct of the interventions on the three major types of intentional communication used prior to speech development, (i. e. initiating joint attention, requesting, and turn-taking). They found that, overall all three communicative functions increased signi? cantly, but RPMT increased turn-taking more than PECS.Children who were higher in initiating joint attention before treatment had greater increases in both initiating joint attention and requesting following RPMT intervention, while those who were initially lower in initiating joint attention had greater increases following PECS intervention. Howlin et al. (2007) conducted a group RCT of 84 children with autism, examining the effect of teacher training and consultancy in PECS. It should be stressed that this study examined the potentiality of a consultancy model to deliver PECS, alternatively than the ef? cacy of PECS per se. Thus, the study was differentiationworthy in that it appears to be the only research to examine effectivene ss (i. e. , outcomes under clinical rather than optimal conditions). Howlin et al. ound that rates of communicative initiations and PECS usage were signi? cantly increased immediately following intervention, but that these effects were not retained once the intervention ceased. They found no signi? cant increase in frequency of speech. Howlin et al. also examined ADOS-G (Lord et al. 2000) domain scores for communication and reciprocal social interaction. They found no increase in most ADOS-G ratings, with the exception of a decrease in the unfeelingness score for the Reciprocal Social interaction domain at the 10 month followup. Unfortunately, no data was provided on the ? delity of implementation of the PECS program, or indeed on the ? delity of the teacher training.Maintenance and Generalization Only ? ve studies provided data on maintenance. Two of the RCT studies included long follow-up. Yoder and Stone (2006a) found that differences in speech variables were not hold 6 mont hs post-intervention, while Howlin et al. (2007) found that for the 26 children assessed at a 10-month follow-up, the increased rate of communicative initiations and PECS usage found immediately post-intervention was not maintained. Two single subject studies and one case study measured maintenance of skills 610 months postintervention (Charlop-Christy et al. 2002 Malandraki and Okalidou 2007 Yokoyama et al. 2006). Charlop-Christy et al. ound that speech and socio-communicative behaviors had been maintained or continued to increase for one participant followed up 10 months post-training. Yokoyama et al. found maintenance of PECS skills both in the training room and at home, 68 months after training for the three participants in their study. Malandraki and Okalidou in their study of one child found maintenance of skills 6 months after the main intervention. While the difference was not signi? cant and the number of studies was low, for the single 123 J Autism Dev Disord (2009) 391471 1486 1481 subject studies both PND and PEM were lower for studies that included maintenance data (Table 4).Fifteen of the 27 studies included some data on generalization of PECS skills. The great majority of these were positive, with skills generalizing to different settings, people and stimuli. For some studies, generalization was an integral part of the way data were collected (CharlopChristy et al. 2002 Yoder and Stone 2006a, b). For others, generalization to untrained situations was speci? cally probed (e. g. , participants in Stoner et al. s (2006) study generalized their skills to use in fast food restaurants). Several studies exhibit generalization to the classroom teacher or to home. In a small number of instances, generalization was unimpressive or absent.For example, in the Adkins and Axelrod (2001) study, tests for generalization simply required the child to mand for an object without immediately prior prompted trials. Carl, from Tincanis (2004) study, failed to generali ze PECS skills to classroom teachers, preferring to use sign language. Discussion The PECS program was originally designed to provide a method of communication for children with autism, particularly those who do not use functional speech. PECS appears to be a popular intervention (Howlin et al. 2007) but, unfortunately, popularity of a given treatment does not necessarily re? ect actual ef? cacy (Green et al. 2006 Reynhout and Carter 2006). Only three RCTs have been reported to date. The studies of Yoder and Stone (2006a, b) compared PECS to RMPT.PECS was superior for some children but the study was designed to compare two treatments and, consequently, did not include a control arm. Thus, no conclusions can be drawn about the relative transcendency of either intervention to a non-treatment control. Howlin et al. (2007) provided the only effectiveness study conducted. They found signi? cant effects on communicative initiations but this was not maintained once the intervention ceased . Thus, further examination of approaches to the delivery of PECS in clinical settings is needed. Con? dence in the Howlin et al. study is or so weakened by the lack of any data on treatment ? delity, which is a critical singularity in study quality (Gersten et al. 2005).The spirit and quantity of data arising from RCTs at this point in time is insuf? cient to draw ? rm conclusions regarding the PECS interventions. Thus, probably the highest precession for research in this area is the conduct of further RCTs examining both ef? cacy and effectiveness in applied settings. In the absence of an adequate body of RCTs, clinicians still need to make informed decisions regarding interventions and may need to look to the second line of evidence. Evidence sanctioning the PECS intervention was provided by the well-designed quasi-experimental studies of Carr and Felce (2007a, b), which incorporated a non-equivalent control group with demonstration of pre-test equivalence between groups.Arg uably, the bulk of interpretable data on PECS comes from single subject studies. For the relevant studies, the overall, mean PND (78. 5%) and PEM (89. 1%) ? gures software documentation the preliminary conclusion that PECS may be an effective intervention, at least when implemented under research conditions. There was a signi? cant difference between the PND results for studies that only looked at picture exchange outcome variables and those that included other related variables, such as speech, social, or challenging behavior. This indicates that, unsurprisingly, PECS training appears to be most effective in providing a successful federal agency of communication through picture exchange.Nevertheless, it should be acknowledged that the number of studies stiff relatively low and single subject designs have several limitations, including low external validity. While these studies contribute to our knowledge and give us a preliminary interpretation of the ef? cacy of PECS, they ar e not a relievo for well-conducted large scale RCTs. A substantial number of the extant studies were preexperimental in nature, particularly the early research. As such, they are not able to provide win over demonstrations of experimental control. Hence, these studies offer no interpretable evidence on the ef? cacy of PECS. The effect of PECS training on speech development remains unclear.Research into various forms of AAC suggests they may have the potential to enhance speech development (Cress and Marvin 2003 Millar et al. 2006 Romski and Sevcik 2005) although results have sometimes been in reconciled (Carter 1999 Millar et al. 2006). Several of the studies reviewed in this paper reported increases in speech following PECS training, but others, including Howlin et al. (2007), reported little or no effect. Where speech increased, this has often occurred concurrently with phase III or IV of PECS, and in particular when a time delay was introduced. A related question, for which the re is as yet no empirical evidence, is whether PECS training affects lore.Brady (2000) found increased comprehension skills with the use of VOCAs and it would be worth investigate whether PECS would have a same effect. In comparison with other AAC systems, recrudesce overall results were obtained with PECS in the studies reviewed here (Adkins and Axelrod 2001 Bock et al. 2005 Chambers and Rehfeldt 2003 Tincani 2004). Nevertheless, there was variation in the results depending on initial imitation skills and, possibly, participant preference. It has been argued that individuals with ASD may bene? t from visually cued instruction (Quill 1997) and further examination of this issue would calculate warranted. In addition, existing 123 1482 J Autism Dev Disord (2009) 3914711486 application of PECS appears to have been exclusively limited to graphic symbols.There are distinct advantages to the use of three-dimensional open symbols, including decreased cognitive load and high iconicit y (Rowland and Schweigert 1989, 1990 Turnell and Carter 1994). The exploration of the use of PECS with patent symbols, especially with individuals who are low functioning, would seem warranted. Only 5 of the 27 studies provided data on maintenance of PECS skills or other dependent variables. It is worthy of note that maintenance was problematic in both RCTs (Howlin et al. 2007 Yoder and Stone 2006a) that examined the issue. Overall, available evidence is mixed but there is certainly suf? cient motion to indicate that maintenance should be formally and consistently monitored in the clinical application of PECS programs.Fifteen studies provided data on generalization of skills, the vast majority of these found that generalization did occur, but what was described as generalization varied greatly. There were several methodological limitations and issues in the research examined that warrant comment. In general, participant descriptions were poor, making it dif? cult to assess whethe r the intervention is best suited to individuals with particular characteristics. While nearly all studies provided a diagnosis, few speci? ed the diagnostic protocol or criteria. Further, when participants were diagnosed with ASD, few researches attempted to quantify the degree of autism.Noting the range of behaviors and symptom unfeelingness possible within individuals presenting with autistic disorder, and even greater variation in the broader autism spectrum, this would seem to be relevant, if not critical, information. Few researchers provided standardized assessment data or a detailed functional description of general ability, but probably re? ecting the engage of the intervention, most did provide some description of initial communication skills. While the number of studies was clearly insuf? cient to reach ? rm conclusions, PND data suggest that individuals with PDD-NOS or showing autistic traits made more progress with PECS than those with autistic disorder.It is unclear whether this is because the PECS protocol is reform suited to them, or because they would do better with any treatment. Without further clear and consistent quanti? cation of the degree of autistic symptomatology, it is impossible to evaluate further this variable in relation to the ef? cacy of the PECS intervention. In addition, there was insuf? cient data on intellectual functioning to change analysis of any relationship to PND or PEM. It is recommended that, in future studies, standardized psychometric data, standardized functional assessment of adaptational behavior, and clear information on initial communicative abilities should be provided.In addition, where a diagnosis of autism is provided the level of autistic symptomatology should be quanti? ed. Procedural reliability data were very limited, with data only tucking the conventional minimum standard in 5 of the 27 studies. Because of the absence of this data, it is not possible to determine in many cases whether what was being implemented was in fact the PECS program as designed. PECS is a complex and multi- instalment intervention making the veri? cation of treatment fair play even more critical. The absence of such information in research studies is somewhat dif? cult to understand given that the PECS manual (Frost and Bondy 2002) gives explicit and speci? criteria for assessing the integrity of training during each phase. Nevertheless, research on PECS is not alone in this regard and lack of procedural reliability data has been reported as a problem in other recent intervention reviews in the area of autism (e. g. , Bellini and Akullian 2007 Reynhout and Carter 2006). The calculated PND (88. 8%) and PEM (89. 9%) ? gures for studies that did fulfil the standard for reportage procedural reliability, are at the high end of the effective intervention range (Ma 2006 Scruggs and Mastropieri 1998), suggesting that monitoring of procedural integrity should be a place feature in research as well as cl inical applications of PECS. A signi? ant component of the present review was the application of PND and PEM metrics to the relevant data. PND and PEM values were in most cases very similar, with lower variability for PEM (see Table 4). An exception was found for data relating to behavioral variables (CharlopChristy et al. 2002 Frea et al. 2001), where high baseline variability and ? oor effects occurred, often causing the calculated PND for alter graphs to be low, while the PEM was high. For example, visual inspection of the graphed data in Frea et al. (2001) shows a clear treatment effect of the PECS intervention on disruptive behavior. Nevertheless, the calculated PND for these data was 0%, while the PEM was 100%.The unlikeness between the clear treatment effect seen in the graphed data and the PND value indicates that PEM may be a more appropriate metric for challenging behavior, where variability is likely to be high. Further, the advantages of using multiple methods of work out effect sizes for single subject research are highlighted. As previously noted, PECS is a complex multi-component intervention program. Consequently, the question arises as to which of the components are most critical to its ef? cacy. For example, reinforcer assessment is formally and systematically incorporated into PECS and this may well be a salient element in program ef? cacy. The use of picture exchange with a partner (rather than base or pointing to a symbol) is a key distinguishing feature of PECS, but it is unclear whether exchange per se is essential to ef? cacy.The issue of developing spontaneity is addressed in an unmistakably systematic way in the PECS program (Chiang and Carter 2008) but extant research 123 J Autism Dev Disord (2009) 3914711486 1483 provides only limited information on the circumstances under which communication occurs. Thus, there would appear to be considerable scope for examination of how speci? c components contribute to the overall ef? cacy of PECS. In addition, there has been only limited comparison of PECS to alternative interventions and this stands as a priority for future research. Several limitations of the current review must be acknowledged. Many of the earlier studies were descriptive and clear experimental control was not established.While later studies were of higher quality, only a limited number of RCTs have been conducted and much of the available interpretable data comes from second line of evidence single subject studies. Analysis of PND and PEM was only possible for a subset of the relevant single subject studies examined and analysis of speci? c study and participant characteristics were based on low numbers. In addition, very few studies provided adequate procedural reliability data so the end to which PECS was appropriately implemented often remained unknown. Conclusion On balance, the studies reviewed provide preliminary evidence that PECS may be ef? cacious for children and adults with ASD and oth er developmental disabilities, who have little or no speech. Primary bene? s appear to be evident in communication by picture exchange. Identi? cation of the core aspects of the program that are important to its success, the individuals to whom it is best suited, and its relationship to other interventions remain to be substantively investigated. PECS stands as a promising intervention with some empirical support but many questions remain. The conduct of further RCTs into the ef? cacy and effectiveness of PECS stands as a high research priority. Appendix cover Table 6. Table 6 Quality criteria for single subject research suitable from Horner et al. (2005) Area Indicator Description of participants Participants are described with suf? ient detail to allow others to select individuals with similar characteristics and settings (e. g. , age, gender, impediment, diagnosis). One point deed overed for each of the following (maximum of 5) 1. Statement of diagnosis such as autism, ASD, As perger syndrome, intellectual disability (with or without indicating diagnostic source), age and gender 2. symptomatic instrument speci? ed (e. g. , WISC, AAMR diagnostic criteria, DSM-IV criteria, ADOS). essential provide if ASD or 0 awarded 3. If ASD, degree of autism speci? ed either with reference to symptoms (DSM-IV) or instrument like CARS. If not ASD, award point 4. Standardized assessment data (e. g. IQ, developmental scale, adaptive behavior) OR detailed functional description of general ability. deadening range (e. g. , moderate) gratifying for intellectual disability 5. Communication skills documented by means of standardized test results OR description of functional skills The process for selecting participants is described with replicable preciseness. essential describe the process used to select participants, not just describe the participants or their needs. This would generally include the criteria the participants must meet (e. g. , 35 years, less than 5 spoken words, diagnosis of autistic disorder) and or the process of selecting participants (e. g. , the ? rst 5 children on the hold list).Essentially, authors must explicitly state HOW/why participants were selected Critical features of the physical setting are described with suf? cient precision to allow restoration Dependent variables All dependent variables are described with operational precision distributively dependent variable is measured with a procedure that generates a quanti? able index The metre process is described with replicable precision Dependent variables are measured repeatedly over time Data are collected on the reliability or inter-observer agreement (IOA) associated with each dependent variable, and IOA levels meet minimal standards (i. e. , IOA = 80% Kappa = 0. 60).Must be on minimum of 20% of sessions to be acceptable Independent variables Independent variable is described with replicable precision Independent variable is systematically manipulated and under th e control of the experimenter Overt measurement of the ? delity of implementation for the independent variable. MUST be measured on a minimum of 20% of sessions to be acceptable 123 1484 Table 6 continued Area service line Indicator J Autism Dev Disord (2009) 3914711486 A baseline phase provides repeated measurement of a dependent variable and establishes a pattern of responding that can be used to predict the pattern of future murder if introduction or manipulation of the independent variable did not occur. Should include a minimum of 3 stable data points.High variability is acceptable if intervention effects are unambiguous The procedural characteristics of the baseline conditions should be described operationally Experimental control/internal The design provides at least three demonstrations of experimental effect at different points in time. cause of validity alternating treatments may be added, as main comparison is not with baseline. AB designs may not be added as they do no t demonstrate intervention at different times when comparing to baseline The design controls for common threats to internal validity (e. g. , permits elimination of rival hypotheses). Acceptable designs include multiple baseline, ABAB and alternating treatment with counterbalancing.Unacceptable designs include AB, ABA, and changing criterion External validity Social validity Experimental effects are replicated across participants, settings, or materials to establish external validity. At least three participants, settings or materials must be apparent The dependent variable is socially important Implementation of the independent variable is practical and cost effective (must be measured) Social validity is deepen by implementation of the independent variable over extended time periods, by typical intervention agents, in typical ph