Available via license: CC BY-NC 4.0
Content may be subject to copyright.
Peer mediation in play settings for
minimally verbal students with autism
Spectrum disorder
Gaëtan Briet
University of NIMES, APSY-V, F-30021, Nîmes Cedex 1, France
Gaïd Le Maner-Idrissi
LP3C (Laboratoire de Psychologie, Cognition, Comportement, Communication),
Université Rennes, Rennes, France
Tanguy Seveno
Centre Hospitalier Guillaume Regnier, Rennes, France
Olivier Le Marec
ADAPEI Morbihan and EPSM Morbihan, Vannes, France
Sandrine Le Sourn-Bissaoui
LP3C (Laboratoire de Psychologie, Cognition, Comportement, Communication),
Université Rennes, Rennes, France
Abstract
Background and aims: Peer-mediated interventions (PMIs) are effective strategies to foster socialization of children
with autism spectrum disorder (ASD) in natural settings. However, research examining the efficacy of peer mediation
for students with ASD who have the greatest cognitive and language impairments remains limited. Additionally, previous
studies essentially targeted communicative abilities of participants. To address this gap, the present study evaluated the
effects of a play-based PMI on three socio-communicative skills (play, social engagement and imitation) of minimally verbal
students with ASD who also have a comorbidity of intellectual disability (ID).
Methods: Seven children with ASD attending ordinary school settings and 14 typically developing (TD) preschoolers parti-
cipated. Seven single-sex groups were formed, and children played together during two 30 min weekly sessions. TD children
were trained according to the principles of the integrated play group model. We used a multiple-baseline design across par-
ticipants to measure the effects of the intervention on play skills, social engagement and motor imitation of students with
ASD.
Results: Outcomes revealed an intervention effect for most of the participants, despite some variations across children.
After the peer training, four children increased their duration of functional/symbolic play, six children improved their duration
of interactive play and five children increased their rates of motor imitation. Concerning maintenance gains, inter-individual
differences are also important.
Conclusions and implications: These findings suggest that a play-based PMI may be a feasible option for targeting inclusive
education and improving socio-communicative skills of some minimally verbal students with ASD who also have an ID.
However, variations across children invite further research to clarify how individual factors can moderate the effects of
PMIs in children with ASD who are the most impaired.
Corresponding author:
Gaëtan Briet, University of NIMES, APSY-V, F-30021, Nîmes Cedex 1, France.
Email: gaetan.briet@unimes.fr
Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution-
NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and dis-
tribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access page (https://us.
sagepub.com/en-us/nam/open-access-at-sage).
Research Article
Autism & Developmental Language
Impairments
Volume 8: 1–17
© The Author(s) 2023
Article reuse guidelines:
sagepub.com/journals-permissions
DOI: 10.1177/23969415231204837
journals.sagepub.com/home/dli
Keywords
Peer-mediated intervention, Autism spectrum disorder, Minimally verbal children, Inclusive education, Play
Introduction
Peer-mediated intervention (PMI) focuses on coaching typ-
ically developing (TD) children to interact socially with
peers who have disabilities (Boudreau et al., 2015). There
is a growing body of research demonstrating the efficacity
of PMIs for improving social participation of children
with autism spectrum disorder (ASD) in inclusive settings
(Gunning et al., 2019). By mobilizing peers as the
primary intervention agents, this approach is a useful and
socially valid strategy for promoting school inclusion of
children with ASD (Hansen et al., 2014). PMIs have been
effective to improve a wide range of social outcomes for
students with ASD, including social initiations and social
responses (Hu et al., 2018), conversational abilities
(Thomas & Bambara, 2020), joint attention (Krier &
Lambros, 2021) and play skills (Kent et al., 2021). By pro-
viding opportunities for children with ASD to interact with
multiple social partners, peer mediation also increases the
possibility of skill maintenance and generalization (Chan
et al., 2009).
To date, PMIs are supported by sufficient high-quality
studies conducted by sufficient different research groups
for being considered evidence-based practices for children
with ASD (Kamps et al., 2017; Wong et al., 2015).
However, recent reviews demonstrated that research on
PMIs in participants with ASD who have the most cognitive
and language difficulties is still limited (Chang & Locke,
2016; O’Donoghue et al., 2021; Watkins et al., 2015).
First, the majority of studies enrolled participants without
intellectual disability (ID) and identified to be ‘moderate
to high functioning’. For example, Watkins et al. (2015)
observed that only three of the 14 studies they reviewed
were conducted in children noted to be ‘low functioning’
(i.e. few or no language skills and IQ < 55). Similarly,
Chang and Locke (2016) noted that most of the studies
enrolled participants who have at least average IQ and
who can communicate through two- or three-word
phrases minimum. Very recently, O’Donoghue et al.
(2021) reviewed PMI studies for minimally verbal children
and observed that only four studies focused specifically on
this population. Thus, as suggested by the authors of these
three reviews, it seems essential to us to include participants
with more complex needs in research on PMIs. Although it
is consistent with the general observation that this popula-
tion described as the ‘neglected end of the spectrum’is
rarely enrolled in scientific studies (Tager-Flusberg &
Kasari, 2013), the search for evidence-based practices
requires to consider the wide spectrum of ASD to determine
whether an intervention that is effective for verbal children
without an ID can also be effective for minimally verbal
children who often have an ID. Second, most of the PMI
studies conducted in minimally verbal children were
similar (O’Donoghue et al., 2021) and focused on coaching
participants to use an augmentative and alternative commu-
nication system. Consequently, the target skills were often
restricted to communication behaviours. For instance,
Trottier et al. (2011) examined the relationship between a
PMI incorporating speech-generating devices and an
increase in appropriate communicative acts of two students
with ASD. Similarly, Thiemann-Bourque et al. (2016)
taught TD children to use the picture exchange communica-
tion system (PECS; Bondy & Frost, 1994) with four pre-
schoolers with ASD to increase their rates of
communication behaviours, modes and functions. Due to
the increasing trend to educate children with disabilities
in the mainstream school setting (Nilholm, 2021), including
those who require the highest levels of support, we feel it is
important to focus on students with ASD with the most sig-
nificant cognitive and language difficulties while consider-
ing more diverse social outcomes than communicative
abilities. Practically, for these students who tend to be edu-
cated in specialized units within mainstream schools, PMIs
could enable them to interact regularly and positively with
TD peers who have been coached and thus really benefit
from the social opportunities offered by the mainstream
setting (Hansen et al., 2014).
Play with objects is an important occupation during
childhood and play skills are central to children’s cognitive
and social development (Goldstein, 2012). However, chil-
dren with ASD often have difficulty playing with peers
and are frequently observed playing alone (Anderson
et al., 2004). They also experience difficulties with sym-
bolic play and frequently produce repetitive and sensory
play behaviours (González-Sala et al., 2021), which is a
barrier to engaging in shared play with TD classmates.
Thus, helping students with ASD to expand their play rep-
ertory and to increase their social exchanges with TD peers
is an important objective for PMI research (Charlop et al.,
2018). Among the existing programs within the literature,
the integrated play groups (IPG) model (Wolfberg, 2003;
Wolfberg et al., 2012) is certainly one of the best described
and validated to promote socialization and play in natural
settings for children with ASD. Grounded in social
2Autism & Developmental Language Impairments
constructivist theory (Vygotsky, 1978), this model focuses
on children with ASD active engagement in culturally
valued activity (i.e. play) through the guidance of more
capable peers (named as expert players) and the support
of an adult group facilitator. To date, a series of studies
using a single-case experimental design (Wolfberg &
Schuler, 1993; Yang et al., 2003; Zercher et al., 2001) or
a group experimental design (Wolfberg et al., 2015) have
been conducted to evaluate the effectiveness of the IPG
model. The accumulated findings indicate that children
with ASD increased their complexity of play (functional
and symbolic) and were more socially engaged (playing
in parallel and in an interactive way) after their participation
in the IPG intervention. At the same time, they spend less
time playing alone and decreased their amounts of not
engaged and sensory play behaviour. Studies also showed
that gains were maintained when adult support was
removed (Wolfberg & Schuler, 1993; Yang et al., 2003;
Zercher et al., 2001) and generalized to unfamiliar peers
(Wolfberg et al., 2015). However, like previously noted
for PMI research as a whole, there is a lack of studies spe-
cifically evaluating the effectiveness of the IPG model for
children who have an ID and who are minimally verbal.
The present study aimed to investigate the effectiveness
of a play-based PMI on socio-communicative skills in chil-
dren with ASD who also have an ID and severe language
impairment. We adopted a single-case multiple baseline
design and asked whether an intervention adapted from
the IPG model and implemented in naturalistic school set-
tings can improve play skills, social engagement and imita-
tion skills. Specifically, we addressed the following
research questions:
1. Was the intervention effective in improving play com-
plexity (from inoccupation and sensory play to func-
tional and symbolic play), social engagement (from
isolate and onlooker play behaviours to parallel and
interactive play) and motor imitation?
2. Was the intervention equally effective for all focal
students?
3. Did the intervention effects maintain in the short term
when adult support was withdrawn?
Method
Participants
Participants were recruited from two schools in western
France, each hosting a specialized unit for students with
ASD and collaborating with the university on research pro-
jects. Seven students with ASD (aged from 3;2 years to 8;9
years) attending a specialized unit and 14 TD students (aged
from 4;11 years and 5;10 years) attending an ordinary class-
room participated. This study complies with the terms of the
Declaration of Helsinki regarding ethical principles
applicable to research involving human beings. Written
consent was obtained from the parents of all children
included in the study. After age-appropriate explanations,
oral consent was also obtained from TD students. Since
children with ASD were not able to provide oral consent,
we were careful about their well-being during play sessions
and stopped the sessions in case of significant discomfort.
Students with ASD. To be included in the study, participants
with ASD had to be enrolled in one of the two specialized
units collaborating with the university. Other inclusion cri-
teria were (a) a clinical record mentioning a diagnosis
of ASD confirmed by a child psychiatrist based on
ICD-10 (World Health Organization, 1992), DSM-IV-TR
(American Psychiatric Association, 2000) or DSM-5
(American Psychiatric Association, 2013) criteria, (b)
limited functional and/or symbolic play skills as demon-
strated by observations during free play, and (c) limited
social interactions with peers as demonstrated by observa-
tions on the playground. Although the diagnosis of ASD
was not confirmed by the research team for the study, all
participants were diagnosed by the psychiatrist of an
expert autism center following the national recommenda-
tions of the ‘Haute Autorité de Santé’. Participants with
ASD were identified as minimally verbal based on a stan-
dardized evaluation of language skills using the
Psychoeducational Profile-Third Edition (PEP-3; Schopler
et al., 2005) and the social cognitive evaluation battery
(Thiébaut et al., 2010). In addition, all children included
in this study used the PECS as the primary means of com-
munication. At the cognitive level, children meet the criteria
for a comorbid ID (DQ <70), as indicated by a measure of
intellectual functioning administered by a licensed psych-
ologist using the French version of the Snijders-Oomen
Nonverbal Intelligence Test (SON-R 21/2-7; Tellegen
et al., 2009). Further descriptions of participants with
ASD are provided in Table 1.
TD students. Children with ASD were paired with 14 TD
students to form seven play groups for the duration of the
study. To ensure that group members were familiar with
each other before the beginning of the study, TD students
were selected from preschool classrooms that already
shared times with students with ASD (e.g., lunch, recess)
before the beginning of the study. We also chose to
recruit preschoolers because functional and symbolic play
is predominant at this age (Lillard, 2015). As recommended
in PMI literature (Charlop et al., 2018), TD participants
were nominated by their teachers according to the five fol-
lowing criteria: (a) children must be willing to participate in
the play sessions, (b) children must regularly attend school,
(c) children must be receptive to instructions given by adult,
(d) children must exhibit age-appropriate social and lan-
guage skills, and (e) children must have a sufficiently
high academic level to compensate for absences from the
Briet et al. 3
Table 1. Description of participants with ASD
Student
Intellectual
developmental
quotient
a
Expressive language and vocal imitation Play and interactions
Anna
Female, 8;9 years
24 •Nonverbal
•No intelligible words and no imitation of
sounds
•Age equivalent in PEP-3: < 1 year
•Did not show much interest
in toys
•Stayed close to the adult and
observed other children
during recess
Bastien
Male, 7;1 years
33 •2–3 intelligible words production
•Approximative novel words imitation
•Age equivalent in PEP-3: 1;4 year
•Used toys for sensory
purposes
•Wandered in the playground,
self-stimulated and
occasionally observed other
children
Caleb
Male, 5;11 years
46 •2–3 intelligible words production
•Approximative novel words imitation
•Age equivalent in PEP-3: 1;5 year
•Manipulated and explored
toys with occasional
functional uses
•Played alone without paying
attention to other children
during recess
Damien
Male, 5;3 months
59 •Fewer than 20 intelligible words and 2 words
sentences used in specific context (request
food)
•Novel words imitation
•Age equivalent in PEP-3: 1;8 year
•Did not show much interest
in toys
•Wandered in the playground
and played alone without
paying attention to his peers
Esteban
Male, 3;2 years
55 •2–3 intelligible words production
•Approximative sounds imitation
•Age equivalent in PEP-3: 1;1 year
•Manipulated objects but only
used a set of toys car in a
functional way
•Wandered in the playground
and occasionally played
beside peers but did not
initiate interactions
Fabio
Male, 7;4 years
42 •Nonverbal
•No intelligible word and approximative sounds
imitation
•Age equivalent in PEP-3: < 1 year
•Demonstrated functional play
acts but restricted to a
specific set of toys (baby doll
and feeding bottle)
•Played alone and did not
initiate with peers
Gary
Male, 6;4 years
50 •Fewer than 20 intelligible words and 2 words
sentences used in specific context (request
food)
•Approximative novel words imitation
•Age equivalent in PEP-3: 1;6 year
•Used toys for sensory
purposes
•Wandered in the playground
and played with his own body
without paying attention to
his peer
a
Obtained from the Snijders-Oomen Nonverbal Intelligence Test (SON-R 2
1/2
-7; Tellegen et al., 2009), by dividing the children’s intellectual developmental
age by their chronological age and multiplying the result by 100. A developmental Quotient (DQ) greater than or equal to 70 indicates no ID, a DQ
between 55 et 69 indicates a mild ID, a DQ between 40 and 54 indicates a moderate ID and a DQ below 40 indicates a severe ID (Lafont et al., 2023).
4Autism & Developmental Language Impairments
classroom during the play sessions. TD students included
twelve boys and two girls, with an average age of 5 years
and 4 months (SD =4 months).
Setting
All participants with ASD attended a specialized unit
located in an ordinary school and received comprehensive
intervention provided by a multidisciplinary team. They
were at school 24 h a week, just like their TD peers. They
received an intensive intervention based on structured
teaching (Schopler et al., 1995) and effective behavioural
and developmental approaches such as the Early Start
Denver Model (Rogers & Dawson, 2010). Thus, each
child had individualized educational objectives targeting
multiple core developmental domains such as social inter-
actions, communication, motricity and cognitive/academic
learning.
Following Wolfberg (2003)’s guidelines, play groups
consisted of one child with ASD and two TD students to
create a natural social setting characterized by a higher pro-
portion of children without disabilities. Given students’
same-sex affiliative preferences during childhood (Martin
et al., 2013), single-sex play groups were formed to encour-
age social interactions that occur more likely in ecological
contexts. Six groups of boys and one group of girls were
therefore created. In each school, boys with ASD were ran-
domly assigned with two TD boys after participants recruit-
ment. All play sessions were conducted in a quiet room
adjacent to the students with ASD’s classroom. In each
room, we used kitchenette furniture and a low shelf to
create a well-defined play area. All sessions were recorded
using a camera mounted on a tripod and placed in a corner
of the room outside the defined play area.
Materials
Based on Wolfberg (2003)’s recommendations, toys were
selected to promote symbolic play and/or social interac-
tions. We ensured that there were equal numbers of male,
female and neutral objects, as the literature shows that
gender influences the choice of objects both by TD children
(Le Maner-Idrissi, 1996) and by children with ASD (Harrop
et al., 2017). Based on Tap (1985)’s classification, four
masculine toys (workbench, set of toy cars, fire engine
and garage), four feminine toys (baby doll, accessories
like teat, feeding bottle and bib, tea set and cash register)
and four neutral toys (ball, jigsaw, magic slate and set of
small farm animals) were placed in the playroom. To
encourage participants to imitate each other, all toys were
available in two. In addition to its learning function, imita-
tion can be used to communicate in minimally verbal chil-
dren with ASD (Nadel, 2002). Thus, by providing two
identical copies of each toy, we aimed to promote
observational learning in students with ASD, while
hoping to facilitate social communication through
imitation.
Experimental design
A single-case multiple baseline design (Kazdin, 2011;
Krasny-Pacini & Evans, 2018) across participants was
used to assess the effects of the intervention. Because the
observations could not start at the same time in the two
schools, this study incorporated non-concurrent multiple
baselines (Christ, 2007; Watson & Workman, 1981),
which is common in applied research such as this one
(Brain & Mirenda, 2019; Katz & Girolametto, 2013). In
such a design, participants were randomly assigned to pre-
determined baselines lengths to ensure that changes in
behaviour occurring after the introduction of the interven-
tion can be functionally related to the treatment.
Following the conventions of the non-concurrent baseline
design (Christ, 2007; Watson & Workman, 1981), partici-
pants of the present study were randomly assigned to base-
line lengths of 6, 8 or 10 sessions. Then, the intervention
was delivered for 10 sessions for all participants, which is
a similar treatment intensity used in other play-based
PMIs (Kent et al., 2021).
Procedures
Thirty-min play sessions were conducted twice a week (on
Mondays and Thursdays or Tuesdays and Fridays, depend-
ing on the participants) with the same experimenter present
for all groups. The experimenter was a licensed psycholo-
gist, trained in working with ASD children and preparing
a PhD in developmental psychology. Play sessions took
place on fixed days and times to be predictable for partici-
pants and professionals. According to Wolfberg (2003)’s
guidelines, a clear timeline was also established within
the play sessions: say hello and sing a song (∼5 min),
play together (∼20 min), put the toys away, sing a song
and say goodbye (∼5 min).
Baseline. During baseline, children were instructed to play
as usual without prompts or feedback from an adult. The
experimenter was seated in a corner of the room but inter-
acted as little as possible with the participants during play
sessions. He occasionally helped to fix broken toys and
ensured that participants were safe during the sessions.
Peer coaching. The experimenter provided coaching to each
group of TD students during four 30-min sessions that
occurred in the same room as the play groups. Students
with ASD were not present during the coaching sessions.
The first session consisted to read and discuss the children’s
book ‘Mont petit frère superhéros’(Roy & Mezher, 2010)
and to watch the animated film ‘Mon petit frère de la
Briet et al. 5
lune’(available online at https://www.youtube.com/watch?
v=T_2lhIy_8zo). Both describe the characteristics of a
child with ASD (strengths and difficulties) as seen from
his sister’s perspective. Thus, TD students were informed
about autism, using age-appropriate vocabulary. Then, the
experimenter led discussions about the importance of
accepting differences between individuals and playing
with peers that are different.
During the second session, behavioural strategies
adapted from Wolfberg (2003)’s IPG model were taught
to the TD students. These strategies were divided into
three categories illustrating what they could DO, what
they could SAY and how to PRAISE their friend with
ASD. The DO category included the following specific
strategies: stay close, take his/her hand, point a toy, give
a toy, show how to play and take turns. The SAY category
included the following strategies: say his/her first name to
get his/her attention, explain what you are doing, ask him
to give you a toy, encourage him to imitate you and ask
him what he wants to play with. Children were taught to
provide verbal instructions by using a language level appro-
priate to the students with ASD (i.e. short sentences of two
—three words). Finally, the PRAISE category included
behaviours such as smiling, doing a high five, clapping
and saying ‘well done’or ‘great’. Three small posters (A4
size) depicting written instruction and pictorial representa-
tion of strategies belonging to the three broad categories
(DO, SAY and PRAISE) were used as visual support for
the children. For each strategy, the experimenter provided
a brief description and modelled at least one example of
its application.
During the last two coaching sessions, strategies were
reviewed with the children. Then, role play was conducted
to give each child opportunities to practice using the strat-
egies. The role play was conducted with the experimenter
as a player who needed support during the third session,
while children took turns playing the role of a player who
needed support during the last coaching session.
Feedback was provided at each attempt to use a strategy
during role play. Children were praised when the strategy
was executed correctly. When a strategy was misused
(e.g. did not call before showing how to play) or missed
(e.g. did not praise after correct play behaviours), the
experimenter provided corrective feedback by executing
the behaviour himself and then asking the child to do it
again.
Intervention. During the intervention, conditions were the
same as in baseline, except that the experimenter encour-
aged TD children to use the newly learned strategies.
Posters depicting strategies and presented during peer
coaching were printed in A0 size and fixed on the wall
inside the play area. TD students could look at them as
much as they needed. The experimenter provided verbal
feedback (e.g. ‘show him how to drink’,‘congratulate
him’) and praise (e.g. ‘keep going, it’s great’) to the TD
children, but avoided being physically involved during
play sessions. During intervention sessions, TD children
were asked to work together to make sure their peer with
ASD had someone to play with but they were primarily
encouraged to structure play interactions on their own
(e.g. who plays with the child with ASD). When, after a rea-
sonable delay (∼1–2 min), the two TD children were
playing without the child with ASD, the experimenter
reminded them to use strategies to also play with him/her.
Follow-up. During follow-up, conditions were the same as in
baseline. The posters were removed from the wall and the
experimenter ceased to provide verbal feedback. Before
each session, TD children were instructed to continue to
play with the child with ASD while being informed that
the adult would no longer assist them in this. The follow-up
phase was conducted immediately after the intervention
sessions. Four follow-up sessions were recorded for all
groups, except for Damien’s in which only three sessions
could be conducted.
Dependent variables
The first author was the primary observer and coded-
dependent variables from the videos of play sessions
using The Observer XT software (Noldus Information
Technologies). Three socio-communicative domains includ-
ing play, social engagement and motor imitation were mea-
sured for all participants with ASD.
The play was coded by recording the duration
(in seconds) of the following four categories of behaviours
(adapted from Wolfberg et al., 2015): not engaged (the
child shows no interest in the toys), sensory play (the
child shows an interest in the toys, handling and exploring
them, but does not conventionally use them), functional
play (the child functionally uses the toys, performing
simple familiar routines involving real-life accessories,
directed to self, doll or peer) and symbolic play (the child
acts as though he was doing something else or being
someone else, with a representational or imaginative
intention).
Social engagement was coded by recording the dur-
ation (in seconds) of the following five categories of beha-
viours (also adapted from Wolfberg et al., 2015): isolated
(the child pays no attention to his peers), onlooker (the
child remains at a distance from his peers, but shows an
interest in them, either watching them or looking at the
toys they are using, without directly joining in their
game), parallel (the child plays alongside his/her play-
mates by simultaneously using similar or identical toys,
but does not interact with them), common focus (the
child interacts with one or more playmates through
verbal exchanges, gifts of objects, turn taking, mutual
imitation or receiving help and instructions) and
6Autism & Developmental Language Impairments
common goal (the child and his peers cooperate in play
activities, explicitly planning each person’s role and per-
forming additional actions in pursuit of a common goal).
Within play and social engagement domains, categories
of behaviours were considered mutually exclusive, so
that distinct behaviours could not be recorded at the
same time. The total duration of each of these behaviours
was collected for each session and then transformed into a
percentage of time to accommodate possible variations in
the total duration of play sessions and obtain comparable
data across sessions and participants.
Motor imitation was coded by counting the number of
behaviours per session that we then converted to a rate
per minute. A motor imitationoccurredwhenthe
student with ASD reproduced a gesture, a posture, a
body movement or an action involving an object that
had been performed by a TD child within the previous
10s. Imitation can be elicited or spontaneous. The
behaviour did not have to be strictly identical to the
model to be recorded, but it did have to resemble it
veryclosely(e.g.mixwithaspoonwhilethemodel
mixes with a fork).
Interobserver agreement
The first author served as the primary data coder and three
students (a PhD student and two bachelor’s level in
psychology) served as reliability coders. All reliability
coders were independent of the experiment, previously
trained to collect reliability data, and blind to the experi-
mental phase they were coding. Reliability coders inde-
pendently coded 20% of randomly selected videos
within each condition for all participants. Inter-rater reli-
ability was calculated for play, social engagement and
motor imitation using a point-by-point-agreement
(Kazdin, 2011). An agreement occurred when both obser-
vers recorded the same behaviour at the same time for all
variables. For play and social engagement, a disagree-
ment occurred when the two coders recorded at the
same time subcategories that are different. For motor imi-
tation, a disagreement occurred when a coder recorded an
occurrence that was not observed by the second observer.
For all variables, the number of agreements was then
divided by the number of agreements plus disagreements
to yield a percentage. Mean interobserver agreement was
94% for play, 92% for social engagement and 96% for
motor imitation, demonstrating good reliability between
the two coders for all variables.
Treatment fidelity
The first author and a PhD student in psychology exam-
ined the videos to ensure that the core components of
the intervention phase were met. For each group, 20%
of the intervention sessions were randomly selected and
examined independently by the two coders. Using an
8-item implementation checklist, they observed whether
(a) TD children used strategies from the SAY category
to help and play with the student with ASD, (b) TD chil-
dren used strategies from the DO category to help and
play with the student with ASD, (c) TD students praised
the student with ASD, (d) the posters were present in
the room, (e) the experimenter provided prompts to the
TD children, (f) the experimenter provided verbal feed-
back to the TD children, (g) the experimenter provided
praise to the TD children and (h) the experimenter did
not physically engage during the play session. Each of
these eight items was rated on a four-point scale (scored
from 0 to 3) according to its presence in the video
(always present, present during more than half of the
opportunities, present during less than half of the oppor-
tunities, never present). The treatment fidelity was then
calculated by dividing the score obtained by the best
score possible (i.e. 24) and multiplying by 100. The
average treatment fidelity during the intervention phase
was 81% (range: 67–94). Cohen’s kappa value was
0.79, demonstrating a substantial interobserver agreement
for treatment fidelity.
Data analysis
We used visual inspection of individual data to examine
changes that occurred between phases, per the conventions
of the single-case design (Kazdin, 2011; Krasny-Pacini &
Evans, 2018). We examined changes from baseline to
intervention for each child in terms of level, trend and vari-
ability. The immediacy of change and the overlap of data
between phases were also considered. To supplement
visual analysis, we calculated a Tau-U effect size metric
for all our dependent variables. Although many methods
exist for calculating an effect size in single-case research,
we chose the Tau-U which was identified as one of the
most relevant (Parker et al., 2011a). Tau-U offers a non-
parametric effect size by calculating the non-overlap of
all pairs of data between baseline and intervention while
controlling for possible trend during baseline (Parker
et al., 2011b). We calculated Tau-U with a web-based cal-
culator (http://www.singlecaseresearch.org/calculators/Tau-U).
Tau-U values range from 0.00 to 1.00 and effects size can be
interpreted as small (between 0.00 and 0.65), medium
(between 0.66 and 0.92) or large (between 0.93 and 1.00)
(Rakap, 2015).
Results
Play skills
To investigate our first research question, the four categor-
ies of play were grouped into only two variables according
to their level of complexity. Figure 1 shows the percentage
Briet et al. 7
of time spent in not engaged/sensory play behaviours and in
functional/symbolic play behaviours by children with ASD
during baseline, intervention and follow-up.
Among the seven participants, four exhibited stable base-
lines and demonstrated more variability in their play beha-
viours after the introduction of the intervention. Anna who
Figure 1. Percentage of time spent in categories of the play domain by children with ASD during baseline, intervention and follow-up.
8Autism & Developmental Language Impairments
was exclusively not engaged or in sensory play during base-
line (100.00%) increased her proportion of functional/sym-
bolic play during the intervention (averaging at 13.32%).
Changes appeared immediately after the introduction of the
intervention, with no overlapping data point between baseline
and intervention. Gains made by Anna then continued to
increase at the follow-up to reach an average of 21.42% of
functional/symbolic play. For Bastien, similar results were
noted as we also observed immediate changes in the two
play variables after the introduction of the intervention,
without overlap in data between baseline and intervention.
On average, his proportion of functional/symbolic play
increased from 0.00% to 12.02%, while his per cent of time
spent not engaged or in sensory play decreased from
100.00% to 86.98%. However, gains made by Bastien were
not maintained at follow-up, as we noted an overall percent-
age of functional/symbolic play during this phase (4.90%)
below the intervention level. For Damien, we observed a
very low percentage of functional/symbolic play during his
first session, which then disappeared completely during the
following baseline sessions. After the introduction of the
intervention, we observed an increase in his overall level of
functional/symbolic play (from 0.13% to 22.88%) and a
decrease in his time spent not engaged or in sensory play
(from 99.87% to 77.12%). Despite some variability in data
within the intervention, the effect was immediate and no
overlap with the baseline was noted. Damien maintained
his gains during follow-up and exhibited an overall percent-
age of functional/symbolic play (18.04%) close to the inter-
vention condition. For Gary, no functional/symbolic play
behaviour was noted during baseline, as he was exclusively
not engaged or in sensory play. After the introduction of
the intervention, we observed immediate changes in variabil-
ity and level of his play behaviours. Overall, his percentage of
functional/symbolic play increased from 0.00% to 14.17%,
while his percentage of time spent not engaged or in
sensory play decreased from 100.00% to 85.83%, with no
overlap between baseline and intervention. He maintained
his gains during follow-up, exhibiting an overall percentage
of functional/symbolic play (13.57%) very similar to the
intervention. For the three other children (i.e. Caleb,
Esteban and Fabio), we did not observe a functional relation-
ship between intervention and play variables. We noted vari-
ability in data within the baseline, without an observable
change in variability, level or trend after the introduction of
the intervention. We also noted multiple overlapping data
points between baseline and intervention. The weighted
average Tau-U for both play variables across participants
was 0.73 [90% CI =0.55–0.91], suggesting a medium
effect of the intervention.
Social engagement
As we did earlier for the play domain, the five categories of
social engagement were grouped into only three variables
according to their level of social play. Thus, Figure 2
shows the percentage of time spent isolated or onlooker,
in parallel play and play with a common focus or
common goal by children with ASD during baseline, inter-
vention and follow-up.
Among the seven participants, six exhibited stable base-
lines and demonstrated more variability in their social skills
after the introduction of the intervention. Anna, who was
exclusively isolated or an onlooker during baseline, spent
more time in play with a common focus/goal during the
intervention (averaging 25.18%). Changes were immediate
with no overlapping data point between baseline and inter-
vention. On average, Anna’s percentage of parallel play
also slightly increased from 0.00% in baseline to 4.49%
during the intervention, but the inconsistency of change
across sessions and the overlaps in data between phases
limited causal attribution. Gains made by Anna in play
with a common focus/goal continued to increase during
follow-up to reach 35.55%. For Bastien, play with a
common focus/goal increased after the introduction of the
intervention (from 0.00% to 13.70%), as well as his
overall percentage of parallel play (from 0.00% to
13.55%). Conversely, his percentage of time spent not
engaged or onlooker decreased from baseline (100.00%)
to intervention (73.11%). Changes observed on these
three variables were immediate with no overlap in data
between baseline and intervention. However, gains made
by Bastien dwindled at follow-up, as indicated by overall
percentages of parallel play (7.68%) and play with a
common focus/goal (3.60%) which were below interven-
tion levels. For Damien, percentages of parallel play and
play with a common focus/goal during the intervention
(averaging at 9.83% and 17.84%, respectively) were
above baseline (averaging at 0.25% and 0.08%, respect-
ively). Conversely, his overall percentage of time spent
not engaged or onlooker during the intervention (72.33%)
was largely below baseline (99.54%). Changes appeared
immediately after the introduction of the intervention with
no overlapping data point between baseline and interven-
tion. Damien maintained his gains during follow-up by
exhibiting, on average, 10.59% of parallel play and
19.41% of play with a common focus/goal. For Esteban,
very similar results were noted. He immediately increased
his percentages of play with a common focus/goal after
the introduction of the intervention (from 0.00% to
21.32% on average), without overlap in data with the base-
line. His percentages of parallel play also increased from
baseline (averaging 3.59%) to intervention (averaging
24.95%) with an immediate effect. Conversely, Esteban’s
overall percentage of time spent isolated or with onlookers
drastically decreased from 96.41% to 53.68%. During
Follow-up, Esteban maintained his gains by exhibiting,
on average, 18.90% of parallel play and 29.39% of play
with a common focus/goal. For Fabio, we noted an imme-
diate effect of the intervention on his proportions of parallel
Briet et al. 9
play which drastically increased from 3.25% in baseline to
24.14% during intervention. Despite more limited gains, his
percentages of play with a common focus/goal also
increased immediately after the introduction of the interven-
tion (from 0.00% to 3.38%), with no overlap in data with
the baseline. Conversely, his overall percentage of time
Figure 2. Percentage of time spent in categories of the social engagement domain by children with ASD during baseline, intervention
and follow-up.
10 Autism & Developmental Language Impairments
spent not engaged or onlooker decreased from 96.75% in
baseline to 72.46% during intervention. The effect was
immediate with only two overlapping data points with a
baseline. Gains made by Fabio during intervention
dwindled at follow-up with 11.64% of parallel play and
0.24% of play with a common focus/goal. For Gary,we
observed an increase in percentages of play with a
common focus/goal after the introduction of the interven-
tion (from 0.25% to 20.86% on average) and a decrease
in percentages of time spent isolated or onlooker (from
99.53% to 70.48% on average). These changes were imme-
diate with no overlap in data between baseline and interven-
tion and maintained during follow-up with overall levels at
21.25% for play with a common focus/goal and 77.56% for
the time spent isolated or onlooker. His percentages of par-
allel play also increased immediately after the introduction
of the intervention and averaged above baseline (8.65%),
but dwindled and trended downward during follow-up
(averaging at 1.17%). For the last participant, Caleb,
visual analysis of data suggested that they were no effect
of the intervention on the social engagement variables.
Indeed, no change in variability, trend or level from base-
line to intervention was noted. Moreover, significant over-
laps between the two conditions were observed. The
weighted average Tau-U was 0.88 [90% CI =0.70–1.00]
for the time spent isolated or onlooker and 0.77 [90% CI
=0.59–0.95] for parallel play, suggesting a medium effect
of the intervention. For play with a common focus/goal,
the weighted average Tau-U was 0.93 [90% CI =0.75–
1.00], suggesting a large effect of the intervention.
Motor imitation
Figure 3 shows the rates of motor imitation exhibited by
children with ASD during baseline, intervention and
follow-up.
Among the seven participants, five exhibited stable
baselines with a total absence of motor imitation and
then demonstrated more variability after the introduction
of the intervention. For Anna, motor imitation immedi-
ately increased to reach an average rate of 0.23 beha-
viours per minute during the intervention, which was
then maintained during follow-up at an average rate of
0.19 behaviours per minute. For Bastien, rates of motor
imitation also increased in level during the intervention
(averaging at 0.50 behaviours per minute), with immedi-
ate effect and no overlapping data point between baseline
and intervention. However, gains dwindled during
follow-up, occurring at an average of 0.25 behaviours
per minute. For Damien, motor imitation increased to
reach an average of 0.42 behaviours per minute during
the intervention. Change appeared immediately after the
introduction of the intervention, with no overlapping
data points between the two conditions. Damien main-
tained his gains during follow-up with motor imitations
occurring on average 0.41 times per minute. For
Esteban, a very similar pattern of change was noted. He
increased immediately his rates of motor imitation after
the introduction of the intervention (averaging at 0.36
behaviours per minute), without overlap with the base-
line. Then, he maintained his gains during follow-up
despite a slightly lower average rate of motor imitation
(0.21 behaviours per minute) than in intervention. For
Fabio, we observed a slight immediate increase in his
rates of motor imitation after the introduction of the inter-
vention (averaging at 0.09 behaviours per minute),
despite four intervention sessions with no behaviour
observed. However, Fabio’s motor imitations trended
downward during follow-up, occurring in only one
session and averaging 0.02 behaviours per minute. For
the two last participants (Caleb and Gary), there was no
observable change in variability, level or trend after the
introduction of the intervention. The two children exhib-
ited imitation behaviours in only two intervention ses-
sions, which is insufficient to support a functional
relationship between intervention and imitation improve-
ment. The weighted average Tau-U for motor imitation
across participants was 0.71 [90% CI =0.53–0.89], sug-
gesting a medium effect of the intervention.
Discussion
The benefits of PMIs for students with ASD are well docu-
mented in the literature (Gunning et al., 2019), but children
with the most substantial cognitive and language difficulties
are largely understudied (Chang & Locke, 2016;
O’Donoghue et al., 2021; Watkins et al., 2015). To
address this gap, the present study aimed to evaluate the
effectiveness of a play-based PMI adapted from the IPG
model (Wolfberg, 2003; Wolfberg & Schuler, 1993) in
seven minimally verbal participants with an ID.
Was the play-based PMI effective to improve
socio-communicative skills of minimally verbal
students who also have an ID?
Our results indicated that the IPG intervention led to socio-
communicative skills improvements in most of the partici-
pants. Within the play domain, four of the seven children
increased their functional/symbolic play behaviours, while
spending less time not engaged or in sensory play. A
similar pattern occurred in the social engagement domain
with increases in parallel play for five children, increases
in common focus/goal for six children and collateral
decreases in isolate/onlooker play behaviours for six chil-
dren. These findings suggest that the intervention led
most of the participants with ASD to demonstrate more
complex and social forms of play, which is consistent
with previous studies on the IPG model (Wolfberg et al.,
Briet et al. 11
2015; Wolfberg & Schuler, 1993; Yang et al., 2003).
Within the imitation domain, five of the seven children
were more imitative after the introduction of the interven-
tion. Imitation is a crucial developmental skill (Edwards,
2014), and children with ASD often have particular
difficulty imitating others’actions (Williams et al., 2004).
Thus, the fact that most of the children were able to
imitate their peers more frequently through the play-based
PMI is particularly notable. In addition, motor imitation
and play with toys predict later communication in children
Figure 3. Rates of motor imitation exhibited by children with ASD during baseline, intervention and follow-up.
12 Autism & Developmental Language Impairments
with ASD (Toth et al., 2006), as well as expressive lan-
guage in those who are minimally verbal (Pecukonis
et al., 2019). Consequently, the joint improvement in play
and imitation skills that we observed in the present study
is particularly encouraging, as progress in these areas
could help minimally verbal children with ASD to
develop communicative and language abilities.
Overall, these findings suggest that the IPG intervention
may be effective to improve the socio-communicative skills
of minimally verbal children with ASD who also have an
ID. However, despite some evidence for improvements
across play skills, social engagement and imitation skills,
there is a notable difference in the degree to which
these three domains responded to the intervention. The
weighted average Tau-U analyses indicated that the effect
of the intervention on play with a common focus/goal
[0.93. (90% CI =0.75–1.00)] was stronger than on func-
tional/symbolic play [0.73 (90% CI =0.55–0.91)] and
motor imitation [0.71 (90% CI =0.53–0.89)]. Thus, these
data suggest that play and imitation skills may be less
responsive to the IPG intervention than social engagement.
Although this is consistent with the primary aim of PMIs
which is to promote socialization (Charlop et al., 2018),
we presume that being aware of the interaction is probably
less demanding than producing new play behaviours or imi-
tating the actions of another, especially for children who
have substantial cognitive difficulties such as those
included in the present study.
Was the play-based PMI effective for all children?
Although there is evidence of improvements across socio-
communicative domains for the majority of the participants,
our results suggest that the IPG intervention was not effect-
ive for all. One child in particular (Caleb) did not make pro-
gress in any domain after the PMI was introduced. Several
explications can be formulated. First, Caleb tended to avoid
social contact with his TD peers and to push back against
their social initiatives during intervention sessions. And
yet, a social approach may be critical to treatment response
for a program that emphasizes social interactions in an
inclusive setting (Ingersoll et al., 2001). For example,
Sherer and Schreibman (2005) observed that children who
had the best outcomes following pivotal response training
exhibited low levels of social avoidance and high levels
of social approach. Conversely, children who showed no
or minimal gains had high levels of social avoidance and
low levels of social approach. Second, Caleb frequently
exhibited disruptive behaviours (crying, running away) in
case of frustrations (e.g. broken toys or desired objects in
possession of a peer), which are identified as barriers to
social relationships and school inclusion within the litera-
ture (Majoko, 2016). It is therefore possible that disruptive
behaviours are also a barrier to the implementation of PMIs,
limiting interactions between peer coaches and children
with ASD. Thus, these results may suggest that for children
with ASD who are socially avoidant and who exhibit dis-
ruptive behaviours, a play-based PMI may not be the pre-
ferred approach for improving socio-communicative
skills. Another explanation based on the children assigned
with Caleb could also be advanced. It was in this group
that the implementation fidelity was the lowest (averaging
at 67%), partly because Caleb’s peers had more difficulty
than other TD participants in the role of coach. They
needed very substantial support from the adult to under-
stand Caleb’s needs and to adjust their behaviour accord-
ingly. They also needed regular encouragement to stay
motivated to help Caleb. Although willing to participate
and identified as socially competent by their teacher,
these observations suggest that TD children’s characteris-
tics may also influence the effects of the IPG intervention
and therefore explain Caleb’s non-evolution.
Beyond differences between Caleb and the other chil-
dren, our results also showed variability among children
who improved, suggesting that intervention was not
equally effective for all. For example, three children simul-
taneously increased their play skills, social engagement and
imitation skills, while the other three children improved in
only two of these domains. Within the play domain, it
seems that the intervention was particularly effective for
children who had the fewest skills at intake. Indeed, the
two children who substantially exhibited functional/sym-
bolic play behaviours in baseline did not progress after
the introduction of the intervention. Conversely, children
who mostly exhibited not engaged/sensory play behaviours
at intake increased their functional/symbolic play beha-
viours when the intervention was introduced. These obser-
vations are encouraging for the diversity of children who
can benefit from the IPG intervention, although they are
not specific to this model. Kent et al. (2021), for instance,
indicated that children with the lowest pre-intervention
play scores improved more than those with the highest pre-
intervention play scores after another play-based PMI.
Practically, such findings suggest that PMIs may be espe-
cially effective for supporting the emergence of new play
skills in children who have the least resources in this area.
Did the intervention effects maintain when adult
support was withdrawn?
Our results indicated that the gains observed in the IPG
intervention were not systematically maintained when
adult support was withdrawn. Maintenance skills concerned
three out of four children for functional/symbolic play, two
out of five children for parallel play, four out of six children
for interactive play and three out of five children for imita-
tion. These data suggest that skill maintenance was pos-
sible, although highly variable across children. We
propose to explain these differences through the interaction
Briet et al. 13
of two factors. First, we observed that students with ASD
who have not maintained their gains were paired with TD
children who had difficulty implementing the intervention
and then drastically reduced their support during follow-up.
For example, Fabio’s peers showed wide fluctuations in
their use of intervention strategies (indicated by an
average treatment fidelity score of 73%) and virtually
stopped helping him when adult support was withdrawn.
Although previous studies were more unanimous on the
capacity of TD peers to continue to carry out activities
without adult guidance (e.g.Harper et al., 2008; Zercher
et al., 2001), the youngest age of the children included in
the present study may explain their greatest difficulty to
implement the intervention accurately and maintain their
support afterward. Second, it appears that the children
who maintained their gains tended to be those with the
most cognitive resources in the sample. For example,
Damien and Esteban who were the two participants with
the smallest cognitive delays maintained their gains, while
Bastien and Fabio who were two of the three children
with the most substantial cognitive delays did not maintain
their gains. Anna was the exception and maintained his
gains despite a very low DQ, but she also was the child
who received the highest level of peer support during and
after the intervention. This would suggest that minimally
verbal children who have the most cognitive difficulties
need continued support to maintain their improvements
over time or that an intervention longer than ten sessions
is necessary to promote ongoing socio-communicative
development.
Limitations and future directions
This study includes several limitations that may provide dir-
ection for future play-based PMI research with minimally
verbal students with ASD. A first limitation has to do
with the fact that we considered motor imitation as a
whole, rather than in its different forms. Given that elicited
and spontaneous imitation respond to functions that are dif-
ferent (Nadel et al., 2004), is it possible that the measure-
ment of these two forms of imitation would reveal more
nuanced findings about intervention effects. Additionally,
children with ASD were encouraged to imitate their TD
peers but intervention procedures did not include the
reverse strategy. To the extent that repeated imitation ses-
sions improve the social functioning of children with
ASD (Field, 2017), it would be relevant to explore
whether incorporating reciprocal imitation into a play-based
PMI could add value. Second, although we observed that
the maintenance of skills was possible immediately follow-
ing the completion of the intervention, we do not know how
long positive effects may persist, or whether they can be
transferred across settings and peers. Future research is war-
ranted to determine whether the gains made by minimally
verbal students with ASD who also have an ID can be
generalized and sustained throughout their childhood. In
addition, the difficulties encountered by some TD peers in
implementing the intervention and in maintaining their
help without adult support raise questions about how they
experienced their role of coach during and after the PMI,
which would also merit further investigations. Third,
although we hypothesize that the variability in intervention
effects across groups can be explained by individual factors,
we do not have sufficient data to confirm this. Future
research is therefore needed to determine to what degree
TD children’s characteristics (e.g. ToM abilities, prosocial
behaviours) and children with ASD’s characteristics (e.g.
cognitive abilities, social avoidance, challenging beha-
viours) influence participants with ASD’s response to a
play-based PMI. Finally, although the present study con-
forms to the standards for multiple baseline design across
participants by incorporating at least three different baseline
lengths (Krasny-Pacini & Evans, 2018), we recognize that it
is more common to have a different number of baseline ses-
sions for each participant.
Conclusion
The present study indicated that a play-based PMI
adapted from the IPG model can be implemented in
school settings for improving play, social engagement
and motor imitation of minimally verbal students with
ASD who also have an ID. Benefits were noted for
most of the participants, although there were inter-
individual variations among children that appeared to
influence performance during intervention and
follow-up. Thus, maintenance of the improvements was
possible without being systematic. Overall, these find-
ings suggest that a play-based PMI adapted from the
IPG model may be a feasible option for addressing inclu-
sive education of students with ASD who have the most
cognitive and language difficulties, especially for pro-
moting positive relationships with their peers.
However, the present study implemented the intervention
in a ‘neutral’room in the school and further research is
needed to determine whether children with ASD requir-
ing the highest level of support and attending specialized
units could benefit from an intervention that would be
directly implemented within a regular class.
Acknowledgements
The authors would like to thank the children and their parents for
their participation, as well as the professionals in the schools for
their help and contributions.
Declaration of conflicting interests
The authors declared no potential conflicts of interest with respect
to the research, authorship, and/or publication of this article.
14 Autism & Developmental Language Impairments
Funding
The author(s) disclosed receipt of the following financial support
for the research, authorship, and/or publication of this article:
the Caisse nationale de la solidarité et de l’autonomie
[Iresp-17-AUT4-06]; the Region Bretagne [ARED 2015-2018],
the ADAPEI 56 [ARED 2015-2018] and the MSHB (for transla-
tion assistance).
ORCID iD
Gaëtan Briet https://orcid.org/0000-0001-8935-8129
References
American Psychiatric Association. (2000). Diagnostic and statis-
tical manual of mental disorders, text revision (DSM-IV-TR).
American Psychiatric Association.
American Psychiatric Association. (2013). Diagnostic and statis-
tical manual of mental disorders DSM-5 (5th Edition).
American Psychiatric Publishing.
Anderson, A., Moore, D. W., Godfrey, R., & Fletcher-Flinn, C. M.
(2004). Social skills assessment of children with autism in free-
play situations. Autism,8(4), 369-385. https://doi.org/10.1177/
1362361304045216
Bondy, A. S., & Frost, L. A. (1994). The picture exchange com-
munication system. Focus on Autistic Behavior,9(3), 1-19.
https://doi.org/10.1177/108835769400900301
Boudreau, A. M., Corkum, P., Meko, K., & Smith, I. M. (2015).
Peer-mediated pivotal response treatment for young children
with autism spectrum disorders: A systematic review.
Canadian Journal of School Psychology,30(3), 218-235.
https://doi.org/10.1177/0829573515581156
Brain, T., & Mirenda, P. (2019). Effectiveness of a low-intensity
peer-mediated intervention for middle school students with
autism spectrum disorder. Research in Autism Spectrum
Disorders,62,26–38. https://doi.org/10.1016/j.rasd.2019.02.
003
Chan, J. M., Lang, R., Rispoli, M., O’Reilly, M., Sigafoos, J., &
Cole, H. (2009). Use of peer-mediated interventions in the
treatment of autism spectrum disorders: A systematic review.
Research in Autism Spectrum Disorders,3(4), 876-889.
https://doi.org/10.1016/j.rasd.2009.04.003
Chang, Y.C., & Locke, J. (2016). A systematic review of peer-
mediated interventions for children with autism spectrum dis-
order. Research in Autism Spectrum Disorders,27,1–10.
https://doi.org/10.1016/j.rasd.2016.03.010
Charlop, M. H., Lang, R., & Rispoli, M. (2018). Want to play?
Peer-mediated intervention for young children with autism
spectrum disorder. In M. H. Charlop, R. Lang, & M. Rispoli
(Eds.), Play and social skills for children with autism spectrum
disorder (pp. 107–127). Springer International Publishing.
http://link.springer.com/10.1007/978-3-319-72500-0_7.
Christ, T. J. (2007). Experimental control and threats to internal
validity of concurrent and nonconcurrent multiple baseline
designs. Psychology in the Schools,44(5), 451–459. https://
doi.org/10.1002/pits.20237
Edwards, L. A. (2014). A meta-analysis of imitation abilities in
individuals with autism spectrum disorders. Autism Research,
7(3), 363-380. https://doi.org/10.1002/aur.1379
Field, T. (2017). Imitation enhances social behavior of children with
autism spectrum disorder: A review. Behavioral Development
Bulletin,22(1), 86-93. https://doi.org/10.1037/bdb0000042
Goldstein, J. (2012). Play in children’s development, health and
well-being. Toy Industries of Europe.
González-Sala, F., Gómez-Marí, I., Tárraga-Mínguez, R.,
Vicente-Carvajal, A., & Pastor-Cerezuela, G. (2021).
Symbolic play among children with autism spectrum disorder:
A scoping review. Children,8(9), 801-819. https://doi.org/10.
3390/children8090801
Gunning, C., Breathnach, Ó, Holloway, J., McTiernan, A., &
Malone, B. (2019). A systematic review of peer-mediated
interventions for preschool children with autism spectrum dis-
order in inclusive settings. Review Journal of Autism and
Developmental Disorders,6(1), 40–62. https://doi.org/10.
1007/s40489-018-0153-5
Hansen, S. G., Blakely, A. W., Dolata, J. K., Raulston, T., &
Machalicek, W. (2014). Children with autism in the inclusive
preschool classroom: A systematic review of single-subject
design interventions on social communication skills. Review
Journal of Autism and Developmental Disorders,1(3), 192–
206. https://doi.org/10.1007/s40489-014-0020-y
Harper, C. B., Symon, J. B. G., & Frea, W. D. (2008). Recess is
time-in: Using peers to improve social skills of children with
autism. Journal of Autism and Developmental Disorders,
38(5), 815–826. https://doi.org/10.1007/s10803-007-0449-2
Harrop, C., Green, J., & Hudry, K. (2017). Play complexity and
toy engagement in preschoolers with autism spectrum disorder:
Do girls and boys differ? Autism,21(1), 37–50. https://doi.org/
10.1177/1362361315622410
Hu, X., Zheng, Q., & Lee, G. T. (2018). Using peer-mediated
LEGO® play intervention to improve social interactions for
Chinese children with autism in an inclusive setting. Journal
of Autism and Developmental Disorders,48(7), 2444–2457.
https://doi.org/10.1007/s10803-018-3502-4
Ingersoll, B., Schreibman, L., & Stahmer, A. (2001). Brief report:
Differential treatment outcomes for children with autistic
Spectrum disorder based on level of peer social avoidance.
Journal of Autism and Developmental Disorders,31(3), 343-
349. https://doi.org/10.1023/A:1010703521704
Kamps, D., Mason, R., & Heitzman-Powell, L. (2017). Peer medi-
ation interventions to improve social and communication skills
for children and youth with autism spectrum disorders. In J. B.
Leaf (Ed.), Handbook of social skills and autism spectrum dis-
order (pp. 257–283). Springer International Publishing. http://
link.springer.com/10.1007/978-3-319-62995-7_16
Katz, E., & Girolametto, L. (2013). Peer-mediated intervention for
preschoolers with ASD implemented in early childhood educa-
tion settings. Topics in Early Childhood Special Education,
33(3), 133-143. https://doi.org/10.1177/0271121413484972
Kazdin, A. E. (2011). Single-case research designs: Methods for
clinical and applied setting (2nd ed.). Oxford University Press.
Kent, C., Cordier, R., Joosten, A., Wilkes-Gillan, S., & Bundy, A.
(2021). Can I learn to play? Randomized control trial to assess
Briet et al. 15
effectiveness of a peer-mediated intervention to improve play
in children with autism spectrum disorder. Journal of Autism
and Developmental Disorders,51(6), 1823–1838. https://doi.
org/10.1007/s10803-020-04671-5
Krasny-Pacini, A., & Evans, J. (2018). Single-case experimental
designs to assess intervention effectiveness in rehabilitation: A
practical guide. Annals of Physical and Rehabilitation Medicine,
61(3), 164–179. https://doi.org/10.1016/j.rehab.2017.12.002
Krier, J., & Lambros, K. M. (2021). Increasing joint attention and
social play through peer-mediated intervention: A single case
design. Psychology in the Schools,58(3), 494–514. https://
doi.org/10.1002/pits.22460
Lafont, C., Panjo, H., Michelon, C., Falissard, B., Speranza, M., Picot,
M.C., Baghdadli, A., & Rouquette, A. (2023). Determinants of
inclusion in mainstream school for children with autism spectrum
disorders from the EpiTED study : A 10-year follow-up cohort.
Journal of Autism and Developmental Disorders,53(1), 121–
131. https://doi.org/10.1007/s10803-021-05404-y
Le Maner-Idrissi, G. (1996). An internal gender system at 24
months. European Journal of Psychology of Education,
11(3), 301–312. https://doi.org/10.1007/BF03172942
Lillard, A. S. (2015). The development of play. In L. S. Liben &
U. Mueller (Eds.), Handbook of child psychology and develop-
mental science (7th ed., Vol. 2, pp. 425–468).
Wiley-Blackwell.
Majoko, T. (2016). Inclusion of children with autism spectrum dis-
orders: Listening and hearing to voices from the grassroots.
Journal of Autism and Developmental Disorders,46(4),
1429-1440. https://doi.org/10.1007/s10803-015-2685-1
Martin, C. L., Kornienko, O., Schaefer, D. R., Hanish, L. D., Fabes, R.
A., & Goble, P. (2013). The role of sex of peers and gender-typed
activities in young children’speeraffiliative networks: A longitu-
dinal analysis of selection and influence. Child Development,
84(3), 921–937. https://doi.org/10.1111/cdev.12032
Nadel, J. (2002). Imitation and imitation recognition: Functional
use in preverbal infants and nonverbal children with autism.
In A. Meltzoff & W. Prinz (Eds.), The imitative mind:
Development, evolution, and brain bases (pp. 42–62).
Cambridge University Press.
Nadel, J., Revel, A., Andry, P., & Gaussier, P. (2004). Toward
communication: First imitations in infants, low-
functioning children with autism and robots. Interaction
Studies. Social Behaviour and Communication in
Biological and Artificial Systems,5(1), 45–74. https://doi.
org/10.1075/is.5.1.04nad
Nilholm, C. (2021). Research about inclusive education in 2020 –
how can we improve our theories in order to change practice?
European Journal of Special Needs Education,36(3), 358–
370. https://doi.org/10.1080/08856257.2020.1754547
O’Donoghue, M., O’Dea, A., O’Leary, N., Kennedy, N., Forbes,
J., & Murphy, C. A. (2021). Systematic review of peer-
mediated intervention for children with autism who are minim-
ally verbal. Review Journal of Autism and Developmental
Disorders,8(1), 51–66. https://doi.org/10.1007/s40489-020-
00201-2
Parker, R., Vannest, K., & Davis, J. (2011a). Effect size in single-
case research: a review of nine nonoverlap techniques.
Behavior Modification,35(4), 303-322. https://doi.org/10.
1177/0145445511399147
Parker, R., Vannest, K., Davis, J., & Sauber, S. (2011b).
Combining nonoverlap and trend for single-case research:
Tau-U. Behavior Therapy,42(2), 284-299. https://doi.org/10.
1016/j.beth.2010.08.006
Pecukonis, M., Plesa Skwerer, D., Eggleston, B., Meyer, S., &
Tager-Flusberg, H. (2019). Concurrent social communication
predictors of expressive language in minimally verbal children
and adolescents with autism spectrum disorder. Journal of
Autism and Developmental Disorders,49(9), 3767-3785.
https://doi.org/10.1007/s10803-019-04089-8
Rakap, S. (2015). Effect sizes as result interpretation aids in single-
subject experimental research: Description and application of
four nonoverlap methods. British Journal of Special Education,
42(1), 11-33. https://doi.org/10.1111/1467-8578.12091
Rogers, S., & Dawson, G. (2010). Early start Denver model for
young children with autism: Promoting language, learning,
and engagement. Guilford Press.
Roy, D., & Mezher, O. (2010). Mon petit frère super héros.
Fonfon.
Schopler, E., Lansing, M. D., Reichler, M. J., & Marcus, L. M.
(2005). Psychoeducational profile-third edition (PEP-3).
Western Psychological Services.
Schopler, E., Mesibov, G. B., & Hearsey, K. (1995). Structured teach-
ing in the TEACCH system. In E. Schopler & G. B. Mesibov
(Eds.), Learning and cognition in autism (pp. 243–268).
Springer US. https://doi.org/10.1007/978-1-4899-1286-2_13
Sherer, M. R., & Schreibman, L. (2005). Individual behavioral
profiles and predictors of treatment effectiveness for children
with autism. Journal of Consulting and Clinical Psychology,
73(3), 525-538. https://doi.org/10.1037/0022-006X.73.3.525
Tager-Flusberg, H., & Kasari, C. (2013). Minimally verbal school-
aged children with autism spectrum disorder: The neglected
end of the spectrum. Autism Research,6(6), 468–478. https://
doi.org/10.1002/aur.1329
Tap, P. (1985). Masculin et féminin chez l‘enfant. Privat.
Tellegen, P., Laros, J., & Kiat, M. (2009). SON-R 21/2–7—Test
non-verbal intelligence. Adaptation Française. Hogrefe.
Thiébaut, E., Adrien, J.L., Blanc, R., & Barthelemy, C. (2010).
The social cognitive evaluation battery for children with
autism : A new tool for the assessment of cognitive and
social development in children with autism spectrum disorders.
Autism Research and Treatment,2010,1–9. https://doi.org/10.
1155/2010/875037
Thiemann-Bourque, K. S., Brady, N., McGuff, S., Stump, K., &
Naylor, A. (2016). Picture exchange communication system
and pals: A peer-mediated augmentative and alternative com-
munication intervention for minimally verbal preschoolers
with autism. Journal of Speech, Language, and Hearing
Research,59(5), 1133–1145. https://doi.org/10.1044/2016_
JSLHR-L-15-0313
Thomas, A., & Bambara, L. M. (2020). Using peer-mediation to
enhance conversation and reduce inappropriate communication
acts in adolescents with autism. Education and Training in
Autism and Developmental Disabilities,55(2), 185–
200. https://www.jstor.org/stable/10.2307/27077910
16 Autism & Developmental Language Impairments
Toth, K., Munson, J., Meltzoff, A. N., & Dawson, G. (2006). Early
predictors of communication development in young children
with autism spectrum disorder: Joint attention, imitation, and
toy play. Journal of Autism and Developmental Disorders,
36(8), 993–1005. https://doi.org/10.1007/s10803-006-0137-7
Trottier, N., Kamp, L., & Mirenda, P. (2011). Effects of peer-
mediated instruction to teach use of speech-generating
devices to students with autism in social game routines.
Augmentative and Alternative Communication,27(1), 26–39.
https://doi.org/10.3109/07434618.2010.546810
Vygotsky, L. S. (1978). Mind in society: The development of
higher psychological processes. Harvard university press.
Watkins, L., O’Reilly, M., Kuhn, M., Gevarter, C., Lancioni,
G. E., Sigafoos, J., & Lang, R. (2015). A review of peer-
mediated social interaction interventions for students with
autism in inclusive settings. Journal of Autism and
Developmental Disorders,45(4), 1070–1083. https://doi.org/
10.1007/s10803-014-2264-x
Watson, P. J., & Workman, E. A. (1981). The non-concurrent mul-
tiple baseline across-individuals design: An extension of the
traditional multiple baseline design. Journal of Behavior
Therapy and Experimental Psychiatry,12(3), 257-259.
https://doi.org/10.1016/0005-7916(81)90055-0
Williams, J. H. G., Whiten, A., & Singh, T. (2004). A systematic
review of action imitation in autistic Spectrum disorder.
Journal of Autism and Developmental Disorders,34(3), 285-
299. https://doi.org/10.1023/B:JADD.0000029551.56735.3a
Wolfberg, P. (2003). Peer play and the autism spectrum: The art
of guiding children‘s socialization and imagination. AAPC
Publishing.
Wolfberg, P., Bottema-Beutel, K., & DeWitt, M. (2012).
Including children with autism in social and imaginary play
with typical peers: Integrated play groups model. American
Journal of Play,5(1), 55–80.
Wolfberg, P., DeWitt, M., Young, G. S., & Nguyen, T. (2015).
Integrated play groups: Promoting symbolic play and social
engagement with typical peers in children with ASD across
settings. Journal of Autism and Developmental Disorders,
45(3), 830–845. https://doi.org/10.1007/s10803-014-
2245-0
Wolfberg, P., & Schuler, A. L. (1993). Integrated play groups: A
model for promoting the social and cognitive dimensions of
play in children with autism. Journal of Autism and
Developmental Disorders,23(3), 467–489. https://doi.org/10.
1007/BF01046051
Wong, C., Odom, S. L., Hume, K. A., Cox, A. W., Fettig, A.,
Kucharczyk, S., Brock, M. E., Plavnick, J. B., Fleury, V. P.,
& Schultz, T. R. (2015). Evidence-based practices for children,
youth, and young adults with autism spectrum disorder: A
comprehensive review. Journal of Autism and
Developmental Disorders,45(7), 1951-1966. https://doi.org/
10.1007/s10803-014-2351-z
World Health Organization. (1992). The ICD-10 classification of
mental and behavioural disorders: Clinical descriptions and
diagnostic guidelines. World Health Organization.
Yang, T.R., Wolfberg, P. J., Wu, S.C., & Hwu, P.Y. (2003).
Supporting children on the autism spectrum in peer play at
home and school: Piloting the integrated play groups model
in Taiwan. Autism,7(4), 437–453. https://doi.org/10.1177/
1362361303007004009
Zercher, C., Hunt, P., Schuler, A., & Webster, J. (2001).
Increasing joint attention, play and language through peer sup-
ported play. Autism,5(4), 374-398. https://doi.org/10.1177/
1362361301005004004
Briet et al. 17
