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RESEARCH ARTICLE
Effects of socially appropriate singing on the
vocal stereotypy of children with autism
spectrum disorder
Benjamin R. Thomas
1
| Marjorie H. Charlop
2
| Nataly Lim
2
|
Caitlyn Gumaer
1
1
Division of Behavioral and Organizational
Sciences, Claremont Graduate University,
Claremont, California
2
Department of Psychology, Claremont
McKenna College, Claremont, California
Correspondence
Benjamin R. Thomas, Division of Behavioral
and Organizational Sciences, Claremont
Graduate University, Claremont, CA.
Email: benjamin.thomas@cgu.edu
Present address
Benjamin R. Thomas, Kennedy Krieger
Institute and Johns Hopkins University School
of Medicine.
Nataly Lim, Department of Special Education,
University of Texas at Austin.
Abstract
This study evaluated the effects of children with autism
spectrum disorder engaging in socially acceptable singing
on their vocal stereotypy. A multiple-baseline across four
participants with embedded multielement designs was used
to assess the effects of the singing intervention upon later
occurrence of vocal stereotypy for each participant. Results
showed that fewer instances of vocal stereotypy occurred
during and after singing intervention sessions. Additionally,
two children began to emit appropriate singing after inter-
vention, which suggests that the topography of their vocal
stereotypy (e.g., monosyllabic or screeching sounds) was
altered to some extent. Overall, results suggest positive
implications for teaching appropriate vocal behaviors as
functional replacements for vocal stereotypy.
KEYWORDS
abolishing operation, autism spectrum disorder, replacement
behavior, singing, vocal stereotypy
1|INTRODUCTION
Vocal stereotypy is a high frequency and disruptive behavior exhibited by many children with autism spectrum disor-
der (ASD; Charlop, Kurtz, & Casey, 1990; Koegel & Covert, 1972; Lanovaz & Sladeczek, 2012; Lovaas, Koegel,
Simmons, & Long, 1973; Rincover, Cook, Peoples, & Packard, 1979). Vocal stereotypy is known to interfere with
learning and the display of adaptive skills (Koegel & Covert, 1972; Lovaas, Newsom, & Hickman, 1987; Matson,
Kiely, & Bamburg, 1997), be disruptive to classroom and inclusive settings (Haley, Heick, & Luiselli, 2010; Yianni-
Coudurier et al., 2008), impair social relationships with peers (Lee & Odom, 1996; Loftin, Odom, & Lantz, 2008;
Received: 29 April 2019 Revised: 4 January 2020 Accepted: 9 January 2020
DOI: 10.1002/bin.1709
Behavioral Interventions. 2020;1–14. wileyonlinelibrary.com/journal/bin © 2020 John Wiley & Sons, Ltd 1
Watkins et al., 2016), and contribute to stigma and stress for families in the community (Austin, Galijot, & Davies,
2018; Austin, Zinke, & Davies, 2016; Gray, 2002; Harnum, Duffy, & Ferguson, 2007). As a core characteristic of ASD
(DSM 5, APA, 2013), stereotypy is one of the most difficult challenging behaviors to treat, and therefore often per-
sists into adulthood (Matson & Dempsey, 2008; Richman et al., 2013).
The form and function of stereotypy can vary across individuals, although they tend to occur most often in the
absence of any socially mediated contingencies (Rapp & Vollmer, 2005), and are often impervious to environmental
disruptions (Koegel & Covert, 1972; Rincover et al., 1979; Wunderlich & Vollmer, 2015). Accordingly, several promis-
ing behavioral approaches have emerged to remediate vocal stereotypy. For instance, interventions involving
matched-stimulation have been associated with immediate, and some subsequent reductions in those maintained by
automatic reinforcement for some children with ASD (Lanovaz & Sladeczek, 2012). The matched-stimulation
approach involves providing a child with access to activities that have sensory consequences hypothesized to be sim-
ilar to that of their stereotypy (Piazza, Adelinis, Hanley, Goh, & Delia, 2000; Rapp, 2007). In this way, access to
matched-stimulation is intended to serve as an abolishing operation (AO) by diminishing the value of stereotypy as a
reinforcer, and thus reducing the motivation to engage in stereotypy for a period of time (Laraway, Snycerski,
Michael, & Poling, 2003).
Several studies have examined the effects of noncontingent auditory stimulation on vocal stereotypy thought to
be maintained by nonsocial auditory consequences (Gibbs, Tullis, Thomas, & Elkins, 2018; Lanovaz, Sladeczek, &
Rapp, 2011; Lanovaz, Sladeczek, & Rapp, 2012). For example, in a series of studies, Lanovaz and colleages (Lanovaz
et al., 2011, 2012, 2014) showed that noncontingent access to music can lead to immediate reductions in vocal ste-
reotypy, as well as increased toy engagement in children with ASD. Across the studies, however, the effects only
maintained for two participants after listening to the music. This may suggest that the two participants' vocal stereo-
typy was maintained by auditory consequences, whereas the music only acted as a competing stimulus for the other
participants (Piazza et al., 2000).
Because vocalizing may differ, acoustically, from the sounds of musical instruments; some studies have also eval-
uated the effects of listening to the human voice as a maintaining reinforcer. For example, Enloe and Rapp (2014)
tested the effects of noncontingent social interaction on the vocal stereotypy of three children with ASD. In their
study, all three children decreased vocal stereotypy while listening to a story read aloud by a therapist. Two of the
children also displayed low levels of motor stereotypy during the story, although the effects did not maintain for
both forms of stereotypy after the story was finished. Saylor, Sidener, Reeve, Fetherston, and Progar (2012) com-
pared the effects of three different types of auditory stimulation (i.e., white noise, music, and audio recording of par-
ticipants' vocal stereotypy) on the vocal stereotypy of two children with ASD. Results indicated that listening to
music or recordings of their own vocal stereotypy resulted in fewer instances of vocal stereotypy than listening to
white noise. Although both music and recordings of participants' vocal stereotypy were equally effective at reducing
vocal stereotypy, music was rated as being more socially valid by participants' parents. Music was also demonstrated
to be most preferred by participants during preference assessments.
Thus, it appears that some children with ASD enjoy listening to music and they may also emit fewer displays of
vocal stereotypy while doing so. Lasting positive effects, however, may be limited for some individuals with this type
of intervention. For example, although listening to music has been associated with an increase in appropriate motor
behaviors such as toy play and task engagement (Lanovaz et al., 2012; Lanovaz et al., 2014), the musical activity
could interfere with participating in therapeutic, educational, or social activities that involve speaking, or listening to
others. Additionally, reductions in vocal stereotypy have rarely maintained immediately after the matched-auditory
stimulation interventions were withdrawn. Therefore, noncontingent access to music or other auditory stimulations
may not be a functional match for children who do not show subsequent decreases in vocal stereotypy (Lanovaz,
Rapp, & Fletcher, 2010). This suggests that vocal stereotypy for some children might be reinforced by other conse-
quences such as the physical sensations (i.e., somatosensory consequences) related to their vocal production
(e.g., vocal fold vibration; Zhang, 2016). In other words, there may be at least two possible sources of reinforcing
stimulation that can maintain vocal stereotypy: vocal-auditory, or vocal-physical consequences.
2THOMAS ET AL.
Although there is no research to date examining physical sensations in the throat or neck as reinforcers for vocal
stereotypy, research on other forms of motor stereotypy, such as repetitive hand movements, appears to support
such a proposition (Lang et al., 2009, 2010; Rispoli et al., 2014). Along these lines, several studies have found that
providing uninterrupted access to motor stereotypy with preferred toys led to reductions in stereotypy post inter-
vention, suggesting that the interventions had abolishing effects (Lang et al., 2009, 2010; Rispoli et al., 2014). For
example, Lang et al. (2010) reduced stereotypy and problem behaviors, and also increased functional play in four chil-
dren with ASD by providing uninterrupted access to motor stereotypy with toys prior to teaching sessions. Similarly,
Rispoli et al. (2014) demonstrated that allowing three boys with ASD to engage in stereotypy with preferred toys
prior to group instruction led to reductions in stereotypy and more appropriate engagement in the group setting.
Thus, given that many individuals presumably have strong, and long lasting reinforcement relationships with their
stereotypy (MacDonald et al., 2007), repeated exposure to the reinforcer maintaining the behavior (rather than
access to stimulation via other sources), might be more effective in altering its motivating control to reduce future
engagement (Murphy, McSweeney, Smith, & McComas, 2003; O'Reilly et al., 2009; Scalzo & Davis, 2016).
In sum, the literature appears to suggest that for intervention procedures to be effective at reducing subsequent
occurrences of stereotyped behavior, the stimulation provided must either be a functional match (Lanovaz et al.,
2010; Lanovaz et al., 2012; Lanovaz et al., 2014; Saylor et al., 2012), or the stimulation must be produced by the indi-
vidual while s/he is engaging in stereotypy (i.e., access to stereotypy; e.g., Lang et al., 2009, 2010; Rispoli et al.,
2014). Because vocal stereotypy might be multiply maintained by auditory and physical sensations of vocalizing
(e.g., vocal cord vibrations) for some individuals, an intervention that provides access to vocalizing might be ideal for
addressing the potential of both sources of reinforcement. According to Lanovaz and Sladeczek (2012), singing can
be considered a form of vocal stereotypy when done alone because there are no social consequences to maintain
it. Unlike most of the vocal stereotypy emitted by individuals with ASD, however, singing is commonly regarded as
socially acceptable because many people sing or hum while alone at home or in their car (Pew Research Center,
2006, in Lanovaz & Sladeczek, 2012). Additionally, singing does not generally impair socialization or task engage-
ment. Because the act of singing produces auditory as well as somatosensory stimulation (i.e., vocal cord vibration),
encouraging children with ASD to sing might address both of these sensory consequences in terms of structural and
functional matching. Moreover, teaching children with ASD to access auditory and somatosensory stimulation
through singing should be a more socially acceptable alternative behavior to other forms of vocal stereotypy
(e.g., screeching). Therefore, the purpose of the current study was to evaluate the effects of singing on the vocal ste-
reotypy of four children with ASD.
2|METHOD
2.1 |Participants
The first participant was Patrick, a 14-year-old Vietnamese-American boy diagnosed with ASD. Patrick was vocally
verbal and participated in an afterschool social skills group with similar age peers. His Vineland-3 (Sparrow,
Cicchetti, & Saulnier, 2016) scores indicated moderately low adaptive functioning. His CARS-2 (Schopler, Bour-
gondien, Wellman, & Love, 2010) scores suggested mild-to-moderate ASD. Prior to the study, Patrick showed the
necessary singing skills by correctly filling in complete phrases of up to seven words, for more than 90% of three
songs. Patrick's vocal stereotypy consisted of speaking in a high pitch and nasal tone. Speaking in this manner made
it difficult for others to understand what he was saying, and also stigmatized him such that children made fun of his
voice and called him a “baby.”
Allen, the second child, was an 11-year-old Korean-American boy diagnosed with ASD. Allen was vocally verbal
and participated in an afterschool social skills group with similar age peers. His Vineland-3 (Sparrow et al., 2016)
scores suggested moderately low adaptive functioning. His ASD was moderate to severe, according to CARS-2
THOMAS ET AL.3
(Schopler et al., 2010) rating. Prior to the study, Allen showed the necessary singing skills by correctly filling in com-
plete phrases of up to seven words, for more than 90% of three songs. Allen's vocal stereotypy involved speaking in
a high pitch and nasal tone. Similar to Patrick, Allen's high pitch voice limited others' understanding of his speech,
and children often poked fun at him.
The third child was Bailey, a 9-year-old Pilipino-American boy who received individual behavioral therapy. Bailey
did not display spontaneous speech, but was able to echo single words, and some two-word phrases. Prior to the
study, Bailey did not have a song repertoire for the presession singing procedure, and thus was taught to sing using
backward chaining and differential reinforcement to increase the length of his singing utterances up to six words. His
Vineland-3 (Sparrow et al., 2016) adaptive functioning was rated as low, and his CARS-2 (Schopler et al., 2010) rating
indicated severe autism. Bailey's vocal stereotypy consisted of repetitively yelling monosyllable sounds, such as “Ah-
Ah-Ah,”or jargon babble-like strings of sounds such as “Du-gaw, yup.”
The fourth child was Dylan, an 11-year-old Vietnamese-American boy who participated in a social skills group.
He had very little spontaneous speech, and responded simple questions with one-word answers. Dylan displayed a
singing repertoire prior to the study, by correctly filling in complete phrases of up to seven words, for more than
90% of three songs. Dylan's adaptive functioning fell in the moderately low range, according to Vineland-3 ratings
(Sparrow et al., 2016). His CARS-2 (Schopler et al., 2010) rating indicated severe autism. Dylan's vocal stereotypy
involved repetitively yelling monosyllable sounds, as well as sustained low-volume monosyllable sounds made with
his mouth closed or slightly open (i.e., humming sounds without a melody).
2.2 |Settings
All data collection sessions for baseline, no-singing control, and postsinging sessions took place in a small therapy
room (approximately 2.5 m by 7 m) that contained a small table, a child-sized chair, and an adult-sized chair. Bailey
and Dylan's singing intervention sessions also took place in the same therapy room, whereas Patrick and Allen sat at
a desk in an office adjacent to the therapy room so they could use a desktop computer for their singing sessions. All
sessions were conducted individually, such that each child was alone with the exception of the researchers.
2.3 |Dependent measures and data collection
The first dependent variable was vocal stereotypy. Patrick and Allen's vocal stereotypy was defined as spoken words
voiced in a high pitch, nasal tone that was significantly above the octaves of their natural vocal registers. Patrick spoke
in a high-pitch and nasal voice almost exclusively, despite requests from adults to speak like a “big boy.”When an
appropriate register was modeled, Patrick did not imitate the model; instead,he spoke in a very low and sometimes uni-
ntelligible register. Similarly, Allen occasionally spoke in a high-pitch register for most vocalizations. He was observed
to occasionally speak in his natural register; however, would not do so when instructed. Like Patrick, Allen spoke in a
very low register when a natural register was modeled. To verify the validity of the operational definitions, 20 under-
graduate psychology students were recruited to evaluate the Patrick and Allen's vocalizations. Each rater was shown
randomly selected video clips with audio that contained three samples each of the children vocalizing in their natural
and high pitch registers (i.e., 60 measurements for each behavior). Agreement was 95% for Patrick's natural and high
pitch register. For Allen, agreement was 98.3% for his natural register, and 100% for his high pitch register.
Spoken phrases containing any instance of vocal stereotypy (i.e., at least one high pitch word) were scored
as a “+.”Phrases in which all emitted words were in their natural vocal register were scored as a “−.”The per-
centage of occurrence score was calculated by dividing the total number of response phrases containing vocal
stereotypy by the total number of opportunities (20 antecedent questions), and then multiplying the quotient
by 100.
4THOMAS ET AL.
For Bailey and Dylan, vocal stereotypy was defined as voiced monosyllabic utterances, words not relevant to
the context, squealing, screeching, or humming tones (without a melody). The presence and absence of vocal stereo-
typy were measured using a 10 s partial interval recording system. Observers used PinPoint Digital Video Coding
and Analysis System software to score the sessions. Intervals that contained vocal stereotypy were scored as a “+,”
and if stereotypy was not observed, the interval was scored as a “−.”The total number of intervals containing vocal
stereotypy was divided by the total number of intervals observed (30), and multiplied by 100 to yield a percentage
of occurrence score.
The second dependent variable was singing, defined as the participant vocalizing a word or approximation from a
recognized song, with or without melody (i.e., changing pitch, rhythm to a recognizable or trained song; singing was
also an independent variable, see below). The presence of singing was measured using 10 s partial interval recording
during the singing sessions for all participants, as well as in baseline, controls, and postsinging sessions for Bailey and
Dylan. Observers used PinPoint Digital Video Coding and Analysis System software to score the sessions. Intervals
with singing were scored as a “+,”and intervals without singing were scored as a “−.”The total number of intervals
containing singing was divided by the total number of intervals observed (30), and multiplied by 100 to yield a per-
centage of occurrence score.
The final dependent variable was singing session time, measured in minutes. Session time was calculated by
summing the number of minutes elapsed, starting from when the participant began to sing, to the end of the session
according to termination criterion (i.e., no longer sang or emitted stereotypy in vocalization for 20 s, or 20 min
elapsed). Participants' average session time was calculated by summing the number of session time minutes and
dividing the total by the number of their sessions.
2.4 |Materials
Three to four songs were included for each participant in the singing intervention. Songs to be included were deter-
mined via parent and therapist report, and as well as participant report for Patrick and Allen only. Bailey and Dylan
sang to therapists, and Patrick and Bailey sang along with the tune played at low volume on YouTube. Prior to each
singing session, participants chose the song they wanted to sing. Most songs were themes to the participants' pre-
ferred television shows or movies. For example, Allen chose songs from the movie Moana and Frozen, whereas Bai-
ley sang the theme songs to Bob the Builder, Scooby Doo, and Sponge Bob. Dylan preferred nursery rhymes such as
Old MacDonald, and Patrick chose hip hop songs from the 1990's such as “Jump”by Kriss Kross.
2.5 |Research designs and procedures
Multiple-baseline across participants, along with embedded multielement designs were used to demonstrate experi-
mental control.
2.5.1 |Functional analysis screening
Prior to the experimental sessions, all participants' stereotypy was initially assessed with an alone plus toys condition
functional analysis (FA; Querim et al., 2013). All participants' stereotypy was present in the alone plus toys condition,
suggesting it was maintained by nonsocial reinforcement. Additional descriptive observations and conversation pro-
bes (Anderson & Long, 2002) for Patrick and Allen during their social skills group indicated that they spoke in high-
pitch voices during demands, social interactions, and when making requests, across various settings, activities, and
social partners.
THOMAS ET AL.5
2.5.2 |Baseline and no-singing control sessions
Baseline and the no-singing control sessions were used to measure the prevalence of naturally occurring vocal ste-
reotypy. Only one baseline and one control session were scheduled per day, and no singing intervention sessions
occurred prior to any baseline or control sessions. Baseline and controls for Patrick and Allen, the two children who
spoke in high-pitched voices, involved answering 20 intraverbal questions during their usual conversation instruction.
This type of measurement context was selected for Patrick and Allen because they participated in a social group with
peers, and FA screening indicated that high-pitch speaking occurred most often when speaking to others. In other
words, high-pitch vocal stereotypy was frequently present when the opportunity to converse arose. Patrick and
Allen sat in a chair across from a researcher and were instructed to answer the questions, to use their regular voice,
and not to speak in a high-pitch voice. Researchers then modeled a regular vocal register and a high-pitch vocal regis-
ter, asked participants if they understood the directions, and answered any questions.
Baseline and control sessions for Bailey and Dylan resembled the alone plus toys FA condition (Querim et al.,
2013), involving 5 min of free play with a preselected assortment of puzzles and action figures. The free-operant
context was selected for Bailey and Dylan because they displayed frequent vocal stereotypy when alone, so this
would allow for measurement of naturally occurring instances of vocal stereotypy that might otherwise be inadver-
tently interrupted by therapist behavior during an instructional session. Bailey and Dylan's sessions were 5 min in
duration.
2.5.3 |Singing intervention
During the singing sessions, participants were given the instruction “Let's sing (song name).”The researcher gave the
first word of the song as a vocal cue, and then periodically gave the next word of a phrase as a prompt if the partici-
pant stopped singing. Patrick and Bailey sang along with songs via YouTube, and Bailey and Dylan sang with thera-
pists. Errors or approximations were not corrected. Singing sessions ended if the participant no longer vocalized for
20 s despite prompts (Lang et al., 2009), or if 20 min elapsed. Patrick and Allen's sessions also ended if their vocaliza-
tions no longer contained high-pitched vocal stereotypy for 20 s, or if 20 min elapsed. Only one presession singing
session occurred per day.
2.5.4 |Postsinging sessions
Immediately after the presession singing, participants were observed in conditions that were identical to their base-
line and controls. Bailey and Dylan had 5 min of free play alone in a therapy room with access to puzzles and action
figures, as in baseline. Patrick and Allen had 5 min of conversation instruction that involved answering 20 intraverbal
questions.
2.6 |Interobserver agreement and procedural reliability
An exact agreement method for measurement of the dependent variables was used across all four participants. Thus,
for Patrick and Allen, total agreement regarding the presence or absence of vocal stereotypy (i.e., high pitch vocaliza-
tion) per phrase, was required for an agreement between the primary and secondary observer. Percent agreement
was calculated by dividing the total number phrases with agreements, by the total number of questions (20), and
multiplying by 100. For Bailey and Dylan, exact agreement was calculated interval by interval. Therefore, the
6THOMAS ET AL.
percentage of agreement was calculated by dividing the total number of intervals containing agreements for vocal
stereotypy, and then singing, by the total number of intervals observed, and multiplying by 100.
Interobserver agreement was calculated for 54.5% of Patrick and 53.8% of Allen's sessions, evenly distributed
across baseline, postsinging sessions, and no-singing controls. Agreement for Patrick's sessions was an average of
94.2% (range, 85–100%). Agreement across Allen's sessions was 94.3%, on average (range, 90–100%). Agreement
was calculated for 50% of Bailey and Dylan's sessions, evenly distributed across baseline, postsinging sessions, and
no-singing controls. Mean agreement for Bailey was 95.6% (vocal stereotypy: M= 92.2% range, 86.7–100%; singing:
M= 98.3%, range, 93.3–100%). Mean agreement for Dylan's sessions was 95.6% (vocal stereotypy: M= 92.8%,
range, 86.7–100%; singing: M= 98.3%, range, 93.3–100%).
Procedural reliability was calculated across the same baseline, postsinging sessions, and no-singing control ses-
sions, for all participants, along with 50% of their singing intervention sessions. Procedural fidelity was for 100% for
Patrick, Dylan, and Allen, across all conditions. For Bailey, procedural fidelity was 100% for baseline, controls, and
postsinging sessions. During the singing sessions, procedural reliability was 90% (range, 80–100%).
All procedures performed in this study were in accordance with the ethical standards of the institutional
research review board and with the 1964 Helsinki declaration and its later amendments or comparable ethical
standards.
3|RESULTS
Figure 1 presents results of the singing intervention for Bailey, Patrick, Dylan, and Allen, during baseline and no-
singing controls (black circles), as well as probes occurring immediately after singing (i.e., postsinging sessions; white
circles). Overall, all four children displayed fewer vocal stereotypy immediately after the singing intervention than
they did in their baseline and no-singing control sessions.
Patrick's data are presented in the top panel. Patrick emitted vocal stereotypic words in 80% to 95% of phrases
during his three baseline sessions. He continued to emit vocal stereotypy in 80% to 95% of phrases. Immediately fol-
lowing the singing sessions, Patrick's vocal stereotypy reduced substantially to a range of 15–35% of phrases, with a
relatively stable and flat trend. As can be seen in in the second panel of Figure 1, Bailey's three baseline sessions
included vocal stereotypy in 83.3–96.7% of intervals. He continued to emit vocal stereotypy in his five control ses-
sions, with scores between 60 and 93.3% of intervals. During postsinging sessions, Bailey's vocal stereotypy immedi-
ately decreased to between 10 and 33.3% of intervals.
The third panel show's Dylan's data. During four baseline sessions, Dylan emitted vocal stereotypy in
66.7–76.7% of intervals. He emitted slightly fewer amounts of vocal stereotypy in his three control sessions (range,
56.7–70% of intervals). Immediately following singing sessions, Dylan's vocal stereotypy decreased substantially,
with his last three sessions ranging between 13.3% and 3.3%of intervals. Finally, Allen's data are presented in the
bottom panel of Figure 1. Allen emitted vocal stereotypy in 60–90% of phrases across his five baseline sessions. Ste-
reotypy was observed to remain stable at 65% of his phrases across all three control sessions. Immediately following
the singing sessions, Allen emitted vocal stereotypy in much fewer of his phrases than he did in baseline or control
sessions (range, 20–40% of phrases).
The duration of singing intervention sessions, and percentage of intervals participants spent singing are pres-
ented in Table 1. Bailey's four singing sessions lasted approximately 7.6 min, on average (range, 5–10 min). Bailey
sang in an average of 87.9% of the intervals (range, 83.3–93.3%), and also emitted vocal stereotypy in an average of
46% of those intervals (range, 40–54.8% of intervals). All of Bailey's singing sessions were terminated because he no
longer engaged in singing for 20 s, despite prompts. Patrick's four singing sessions averaged 8.1 min (range,
6.5–10.3 min). He sang in a high-pitch stereotypy voice during an average of 83.1% of the intervals (range,
75.6–88.7%). All Patrick's singing sessions were terminated because he stopped singing in his high-pitch voice, and
began to sing in his natural vocal register for at least 20 s. All of Dylan's five singing sessions were terminated at the
THOMAS ET AL.7
maximum time of 20 min. Dylan sang in an average of 99.4% of intervals (range, 99.2–100%), and emitted vocal ste-
reotypy in an average of 11.8% of intervals (range, 4.1–21.7%). Finally, Allen's singing sessions lasted approximately
9.2 min, on average (range, 3–15 min). In his singing sessions, Allen sang in an average of 81.0% of the intervals
(range, 80.0–82.6%). All of Allen's singing sessions ended when he used his natural vocal register for at least 20 s.
Figure 2 presents the average percentage of Bailey and Dylan's vocalizations that were composed of appropriate
singing during baseline, no-singing controls, and postsinging sessions. Patrick and Allen's sessions did not occur
0
20
40
60
80
100
12345678910111213
Sessions
Percent of Occurrence
Bailey
Patrick
Allen
Dylan
0
20
40
60
80
100
Baseline Intervention
No Sing ing
Post -Singing Session
0
20
40
60
80
100
0
20
40
60
80
100
FIGURE 1 Percentage of vocal stereotypy occurrence during baseline and no-singing controls (black circles), as
well as probes occurring immediately after singing sessions (white circles)
8THOMAS ET AL.
under free-operant conditions, and thus were not analyzed for appropriate singing during baselines. Bailey's results
are presented in the top panel, and Dylan's are presented in the bottom panel. During baseline, Bailey did not display
any appropriate singing (0%). After initiating the singing intervention, singing began to emerge in Bailey's no-singing
control sessions, increasing from 3.4 to 14.3% of vocalizations (M= 9.3% for no-singing control sessions). In his pos-
tsinging sessions, Bailey displayed singing in an average of 26.9% of his vocalizations, increasing from 18.2 to 33.3%
in later sessions. Similarly, Dylan did not display appropriate singing in his baseline sessions (0%). Singing was then
observed in an average of 10.5% of his control sessions after participating in the intervention, ranging from 5.9 to
15.0% of intervals. During postsinging sessions, singing comprised 44.4% of Dylan's vocalizations, on average (range,
30.8–75% of observed vocalizations).
4|DISCUSSION
The present study used a multiple-baseline across participants with embedded multielement designs to assess the
effects of presession singing on the prevalence of vocal stereotypy in four boys with ASD. Results showed that
TABLE 1 Within-session singing times and percentage of intervals with singing
Participant Session time Avg. # min Singing Avg. % intervals
Bailey 7.6 min (range, 5–10 min) 87.9% (range, 83.3–93.3%)
Patrick 8.1 min (range, 6.5–10.3 min) 83.1% (range, 75.6–88.7%)
Dylan 20 min (max) 99.4% (range, 99.2–100%)
Allen 9.2 min (range, 3–15 min) 81.0% (range, 80.0–82.6%)
0.0%
10.5%
44.4%
0%
10%
20%
30%
40%
50%
Baseline Control Post-Singing
Dylan
0.0%
9.3%
26.9%
0%
10%
20%
30%
40%
50%
Bas elin e Control Post-Singing
Bailey
Percent of Vocalization s with App ropriate Singing
Con ditions
FIGURE 2 The average percentage of
vocalizations that were composed of
appropriate singing during baseline, no-
singing controls, and postsinging sessions
for Bailey (top panel) and Dylan (bottom
panel)
THOMAS ET AL.9
engaging in singing decreased subsequent engagement in vocal stereotypy across the four participants. Two partici-
pants, Patrick and Allen, spoke in high-pitch voices almost exclusively, during baseline (range, 60–96.7% of phrases).
After singing in their high-pitched voices, both boys spoke significantly more often in their natural vocal registers.
Bailey and Dylan displayed frequent noncontextual and atypical sounds in upward of 95% of intervals during base-
line sessions. During the singing sessions, Dylan emitted stereotypy in fewer than 25% of intervals, on average, and
Bailey's were reduced by approximately 50%, on average. Immediately after the singing sessions, vocal stereotypy
was substantially reduced for both participants compared to baseline, control, and singing sessions. Thus, engaging
in singing appears to have been a functional match (Lanovaz et al., 2010) and served as an AO for all four partici-
pants' vocal stereotypy (Laraway et al., 2003; O'Reilly et al., 2009; Scalzo & Davis, 2016).
The results of this study offer some insight into examining the possible reinforcing relationship of the physical
sensations associated with vocalizing (e.g., vocal cord vibration). According to Lanovaz et al. (2010), subsequent
reductions in behavior are indicative of a functional match, or that the stimulation had similar consequences to that
of the child's stereotypy. For example, studies using noncontingent access to auditory stimulation have shown subse-
quent decreases in vocal stereotypy for some children after they are no longer listening to music or human voices
(Lanovaz et al., 2010; Lanovaz et al., 2011; Lanovaz et al., 2012; Lanovaz et al., 2014; Saylor et al., 2012), suggesting
it's effective as an AO (Laraway et al., 2003). Yet, the same procedures did not serve as AOs for vocal stereotypy
across many other children who resumed vocal stereotypy immediately after the auditory stimulation was removed
(Lanovaz et al., 2010; Lanovaz et al., 2011; Lanovaz et al., 2012; Lanovaz et al., 2014; Saylor et al., 2012). The
absence of the physical sensory component, then, might explain why some children do not respond to treatments
involving noncontingent access to music, voices, or sound-producing toys. In the current study, decreases in vocal
stereotypy were observed immediately after the singing intervention for all four children. In addition to the auditory
stimulation from hearing their own voices, singing also provided participants with physical stimulation via vocal cord
vibrations. Thus, singing appears to have been an effective AO for vocal stereotypy because it provided both audi-
tory and physical stimulation, allowing satiation from both types of stimulation to occur (O'Reilly et al., 2009). Thus,
a functional match via physical sensory stimulation, as well as prolonged access to the stimulation, could be impor-
tant considerations when evaluating the outcome of a reduction procedure to determine its viability as an AO for
vocal stereotypy.
The present results also suggest that teaching children with ASD to sing might also lead to the development of
an appropriate replacement behavior to stereotypy (Luiselli, Ricciardi, Zubow, & Laster, 2004). Notably, appropriate
song content and melodies began to emerge in Bailey and Dylan's vocalizations while they were alone, taking the
place of their original vocal stereotypy (e.g., squealing, screeching, etc.). For these two participants, there is some evi-
dence to suggest that the singing intervention not only decreased vocal stereotypy but also altered the topography
of their vocal stereotypy into a more socially acceptable form.
Learning to sing may also function as a behavioral cusp for children with ASD. Behavioral cusps are behav-
iors that allow an individual to access and contact new environments and contingencies (Rosales-Ruiz & Baer,
1997). Many individuals with ASD have difficulties with social communication and interactions (DSM 5; Ameri-
can Psychiatric Association, 2013), which often leads to difficulties forming and maintaining friendships
(Fuentes et al., 2012). Research has demonstrated that having shared interests is an important factor that con-
tributes to the formation of friendships (Rekalidou & Petrogiannis, 2011). For example, many children with and
without ASD enjoy musical movies and music groups. Engaging in singing instead of vocal stereotypy may allow
individuals with ASD to be involved in several related social activities, such as choir, glee club, or musical the-
ater. Participation in such groups would provide more opportunities for children with ASD to develop singing or
performing skills as well as increase occasions for social interaction and improve social competence (Corbett
et al., 2014; Corbett et al., 2016), which may in turn facilitate the formation of friendships. For example, Donald
T., the first individual diagnosed with ASD, was reported to display frequent and various forms of vocal stereo-
typy across his youth (Kanner, 1943), and this later developed into membership in his college a capella choir
(Donvan & Zucker, 2010).
10 THOMAS ET AL.
There are some potential limitations to the findings of this study and avenues for future investigation that
are worth noting. First, some research suggests that physical activity (e.g., walking, jogging, or playing ball games) is
associated with subsequent reductions in various forms of motor and vocal stereotypy (e.g., Celiberti, Bobo, Kelly,
Harris, & Handleman, 1997; Kern, Koegel, Dyer, Blew, & Fenton, 1982; Kern, Koegel, & Dunlap, 1984; Rosenthal-
Malek & Mitchell, 1997). In this study, it is plausible that singing could be considered a form of vocal exercise, and
this may have contributed to decreased engagement in vocal stereotypy for some participants immediately following
singing, in addition to possible satiation effects. Patrick and Allen's vocal stereotypy (high pitch speaking), however,
was measured relative to conversational opportunities rather than nonsocial vocalizations while alone. During their
postsinging sessions, both boys participated in their communication training data collection sessions and were not
observed to speak less often (i.e., nonresponding). Second, postsinging sessions involved free play, whereby singing
would not be disruptive and was an acceptable alternative behavior for vocal stereotypy. However, singing would
not likely be an acceptable behavior for a student to engage in during class. Future research may wish to investigate
whether reductions in vocal stereotypy would still be displayed if participants were not allowed to sing in post-
intervention sessions such as work tasks. Third, we did not compare singing to a noncontingent music intervention.
Some external auditory stimulation was also present during the singing intervention, however, such as the therapist
singing and the YouTube videos and this may have enhanced the auditory aspect to some degree. However, partici-
pants were continually prompted to continue singing, and within session data indicate that the children sang during
the majority of the intervention. If they stopped singing for >20 s, the session ended according to protocol. There-
fore, the present protocol considerably minimized opportunities for passive listening. Finally, postsinging sessions
were only 5 min in duration. Future research may benefit from extending the period of time after an intervention to
determine how long effects may last.
In summary, vocal stereotypy can be difficult to treat, because it may in fact be serving one or two different
functions, such as vocal-auditory, and/or vocal-physical reinforcement. To date, addressing the physical sensa-
tions of vocalizing as a source of reinforcement has been less explored in the literature. Decreasing motivation
to engage in vocal stereotypy (e.g., sounds or high pitch speaking) while increasing topographically similar and
appropriate singing behaviors seems to be a promising course of treatment. Specifically, singing may allow chil-
dren with ASD to contact both auditory and physical stimulations that could be maintaining reinforcers for their
vocal stereotypy. Thus, the results of the present study suggest that teaching socially acceptable vocal behaviors
may act as an AO for vocal stereotypy, and also may be a potential functional replacement behavior for vocal
stereotypies.
ACKNOWLEDGEMENTS
We thank Kristin Nishimura for help with data analysis, and W. V. Dube and the University of Massachusetts Medi-
cal School for providing the PinPoint Digital Video Coding and Analysis System software.
CONFLICT OF INTERESTS
The authors declare no conflicts of interest.
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable
request.
ORCID
Benjamin R. Thomas https://orcid.org/0000-0001-6866-7854
Nataly Lim https://orcid.org/0000-0001-9449-5996
THOMAS ET AL.11
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How to cite this article: Thomas BR, Charlop MH, Lim N, Gumaer C. Effects of socially appropriate singing
on the vocal stereotypy of children with autism spectrum disorder. Behavioral Interventions. 2020;1–14.
https://doi.org/10.1002/bin.1709
14 THOMAS ET AL.
