© Springer International Publishing AG 2017
J.L. Matson (ed.), Handbook of Childhood Psychopathology and Developmental
Disabilities Treatment, Autism and Child Psychopathology Series,
An Introduction to Applied
Justin B. Leaf, Joseph H. Cihon, Julia L. Ferguson,
and Sara M. Weinkauf
What Is Applied Behavior Analysis? 25
Basic Principles of ABA .......................................... 26
ABA-Based Procedures .......................................... 27
Conclusion ............................................................... 38
References ................................................................ 38
What Is Applied Behavior Analysis?
Applied behavior analysis (ABA) is one of the
three branches of the science of behavior analy-
sis, the other two being the experimental analysis
of behavior and behaviorism, or the philosophy
of behavior (Cooper, Heron, & Heward, 2007).
As a science, ABA can be described as a system-
atic approach to understanding behavior of social
interest. ABA is deeply rooted in the inﬂuential
work of individuals such as Edward Thorndike,
John Watson, Ivan Pavlov, and B.F. Skinner, to
name a few. In 1968, Baer, Wolf, and Risley out-
lined some of the deﬁning characteristics research
in ABA should exhibit in their seminal paper
“Some Current Dimensions of Applied Behavior
Analysis.” While there are many examples of
applied behavior analytic research prior to Baer
et al. (e.g., Allen, Hart, Buell, Harris, & Wolf,
1964; Ayllon, 1963; Ayllon & Azrin, 1965; Ayllon
& Michael, 1959; Etzel & Gerwitz, 1967;
Sherman, 1963; Wolf, Risley, & Mees, 1963), its
publication, along with the establishment of the
Journal of Applied Behavior Analysis, is com-
monly cited as what established the ﬁeld of ABA.
Baer, Wolf, and Risley (1968, 1987) urged
research in the ﬁeld of ABA to be applied, behav-
ioral, analytic, technological, conceptually sys-
tematic, effective, and generalizable; applied in
the sense that the subject matter is selected due to
its importance to the individual, community, and/
or society. ABA research is behavioral in that the
subject matter is observable, objectively deﬁned,
and measurable. Research demonstrates the ana-
lytic dimension when there has been a believable
demonstration that the intervention, or
independent variable, is solely responsible for
changes in the behavior in question, or the depen-
dent variable. This dimension is typically
J.B. Leaf (*) • J.L. Ferguson
Autism Partnership Foundation,
Seal Beach, CA, USA
Autism Partnership Foundation,
Seal Beach, CA, USA
Endicott College, Beverly, MA, USA
JBA Institute, Aliso Viejo, CA, USA
assessed through the research design used in the
study. ABA research is technological when the
procedures are described completely to allow the
possibility of replication. To be conceptually sys-
tematic, research in the ﬁeld of ABA provides
descriptions of interventions and changes in
behavior that align with relevant principles of
behavior analysis. Baer et al. (1968, 1987) con-
sidered research that has demonstrated effects
that have practical value and are meaningful to
the participants as effective. Generality is demon-
strated when the results are lasting and occur
across different contexts (e.g., environments,
people, times of day, with different materials).
An additional important component of ABA,
while not included in Baer et al. (1968, 1987)’s
description of some of the dimensions of ABA, is
social validity. The importance of which was dis-
cussed by Wolf (1978). Judgments on social
validity often involve inquiry on three factors: (1)
the signiﬁcance of the goals selected, (2) the
appropriateness of the procedures utilized, and
(3) the importance of the effects demonstrated
(Wolf, 1978). Unlike most measures within
behavior analytic work, social validity is often
subjective (e.g., done through questionnaires, rat-
ing scales, and interviews). Social validity mea-
sures combined with objective measures allow
researchers and practitioners to measure the
effectiveness and social acceptability of
As a practice, ABA refers to the application of
behavior analytic principles to improve socially
important behaviors, for example, the use of
shaping to expand the food repertoire of an indi-
vidual exhibiting food selectivity (e.g., Koegel
et al., 2012). In this example, shaping, an empiri-
cally evaluated behavioral technique, is employed
to improve an assumed socially relevant difﬁ-
culty. While the clinical application of ABA may
not require the experimental rigor common to
research in ABA, it still should align with the
dimensions outlined at its conception. In prac-
tice, the principles of ABA have been employed
across a wide spectrum of challenges. Some
examples include, but are not limited to, the treat-
ment of developmental disabilities, such as
autism spectrum disorder (ASD; e.g., Lovaas,
1987; Ivar Lovaas, Koegel, Simmons, & Long,
1973), as well as gerontology (e.g., Green, Linsk,
& Pinkston, 1986), education (e.g., Hall, Lund, &
Jackson, 1968), juvenile delinquency (e.g.,
Phillips, Phillips, Fixsen, & Wolf, 1971), nonhu-
man welfare (e.g., Dorey, Rosales-Ruiz, Smith,
& Lovelace, 2009), healthcare (e.g., Lichtenstien,
1997), addiction (e.g., Silverman, Roll, &
Higgens, 2008), relationships (e.g., Sanders,
1999), and sustainability (e.g., Bekker et al.,
Basic Principles of ABA
As mentioned previously, ABA-based procedures
are derived from the principles of the science of
behavior analysis to allow for socially signiﬁcant
behavior change to occur. Behavior can be
That portion of an organism’s interaction with its
environment that is characterized by detectable
displacement in space through time of some part of
the organism and that results in a measureable
change in at least one aspect of the environment.
(Johnston & Pennypacker, 1993, p. 23)
The principles of behavior analysis began
their development from early work on respondent
and operant conditioning. In respondent condi-
tioning, behavior is elicited through a condi-
tioned or unconditioned stimulus. For example,
presenting food, an unconditioned stimulus, elic-
its salivation, an unconditioned response. If a
light is paired with the onset of food, eventually
the light alone will elicit salivation. While
respondent conditioning has been utilized within
ABA-based procedures and should be considered
in some contexts, the principles of operant behav-
ior are more common within practice.
Within the operant conditioning paradigm,
behavior is changed through manipulating ante-
cedents and consequences (i.e., what comes
before and after the behavior in question).
Antecedent manipulation involves changes to the
stimulus conditions prior to the potential onset of
the targeted behavior. Consequent manipulation
involves reinforcement and punishment.
Reinforcement occurs when a stimulus change
J.B. Leaf et al.
occurs contingent upon a behavior that results in
a corresponding increase in the probability of
similar behavior occurring in similar situations in
the future. Punishment occurs when a stimulus
change occurs contingent upon a behavior that
results in a corresponding decrease in the proba-
bility of similar behavior occurring in similar
situations in the future.
What follows are brief descriptions and
research examples of some procedures that uti-
lize the principles of ABA to modify behavior.
This list is not meant to be exhaustive, but rather
a sample of some commonly used procedures
within practice and research. Additionally, the
research examples selected for each procedure
were done to simply provide an example of the
procedure used in the professional literature.
These examples are not meant to be representa-
tive of a review of the body of literature as a
whole for any given procedure.
Discrete Trial Teaching
One of the most common approaches to teaching
within a behavior analytic framework is discrete
trial teaching (DTT; Lovaas, 1981, 1987). This
systematic procedure is commonly used to teach
a variety of skills. Each discrete trial consists of
three primary components: (1) a discriminative
stimulus (e.g., an instruction from the interven-
tionist), (2) a response by the learner, and (3) a
consequence (i.e., reinforcement or punishment)
provided by the interventionist. An optional, but
common, fourth step involves providing a
prompt, prior to the learner’s response, that
increases the likelihood of the learner responding
correctly. Other important components which
have been explored within experimental evalua-
tions of DTT include inter-trial intervals, meth-
ods of data collection, and establishing operations
(EO; Keller & Schoenfeld, 1950; Michael, 1988).
Researchers have demonstrated that DTT has
been an effective approach to teach a variety of
skills such as receptive and expressive labels
(e.g., Conallen & Reed, 2016; DiGennaro-Reed,
Reed, Baez, & Maguire, 2011), conversation
skills (e.g., Ingvarsson & Hollobaugh, 2010), and
play and social skills (e.g., Nuzzolo-Gomez,
Leonard, Ortiz, Rivera, & Greer, 2002;
Shillingsburg, Bowen, & Shaprio, 2014).
In a recent speciﬁc example, Conallen and
Reed (2016) used a DTT approach to teach sev-
eral children (ages 6–9 years), diagnosed with
autism, to label the emotions of others. Situational
cards were placed in front of the participants that
depicted various scenarios that are likely to occa-
sion a speciﬁc emotion (e.g., a boy at a birthday
party). The participant was then given a picture
of a boy displaying a happy, sad, or angry facial
expression and asked to match the card to the
situational card. Following the match-to-sample
condition, the researchers then presented each
participant with a situational card and asked a
question related to that card (e.g., “It is his birth-
day, how does he feel?”). The participants
answered by selecting the picture of the boy dis-
playing an emotion (i.e., happy, sad, or angry).
Conallen and Reed found that the procedure was
successful at teaching the participants to label
emotions within this context. For a more in-depth
description of DTT, we refer the reader to Ghezzi
(2007), Leaf and McEachin (1999), Lerman,
Valentino, and LeBlanc (2016), Smith (2001),
and Leaf, Cihon, Leaf, McEachin, and Taubman
To minimize errors, increase correct responding,
and increase the rate of reinforcement, prompts
are often provided to assist the learner. Prompts
are any antecedent behavior the interventionist
engages in that alters stimulus conditions to
increase the likelihood of the desired response
(Green, 2001; Grow & LeBlanc, 2013; MacDuff,
Krantz, & McClannahan, 2001; Wolery, Ault, &
Doyle, 1992). There are many ways an interven-
tionist can provide a prompt, which include, but
is not limited to, pointing to the correct response
(e.g., Soluaga, Leaf, Taubman, McEachin, &
Leaf, 2008), physically guiding the learner to the
correct response (e.g., Leaf, Sheldon, & Sherman,
An Introduction to Applied Behavior Analysis
2010), reducing the number of choices in the
ﬁeld (e.g., Soluaga et al., 2008), verbally model-
ing the correct response (e.g., Leaf, Sheldon, &
Sherman, 2010), or placing the target stimulus
closer to the learner (e.g., Soluaga et al., 2008).
Although researchers have shown that prompt-
ing can be effective across multiple populations
and behaviors, it may be difﬁcult for clinicians to
know when to prompt, fade prompts, and what
prompts to provide. Thus, researchers have eval-
uated various prompting systems to help guide
clinicians to effectively utilize prompts. One way
to provide and fade prompts is to develop a
prompting hierarchy. One method is known as
least-to-most prompting which starts with inter-
ventionist providing the least amount of assis-
tance and gradually increasing the assistance
based on learner responding. A second hierarchi-
cal prompting system is known as most-to-least
prompting which starts with the most assistive
prompt (e.g., full physical guidance), and, over
successive trials or sessions, the interventionist
reduces the level of assistance. When using hier-
archical prompting systems, professionals typi-
cally determine the number of steps in the
prompting hierarchy, what types of prompts will
be provided, the level of assistance, the criteria to
fade or reintroduce prompts, and what types of
reinforcers will be utilized for unprompted and
A second way to provide and fade prompts is
based on manipulation of the time until a prompt
is provided. One common way to do this is to
implement a prompting system referred to as a
progressive time delay. During initial teaching
with progressive time delay prompting, the inter-
ventionist presents a set number of simultane-
ously prompted trials (i.e., 0 s delay). After a set
number of simultaneously prompted trials, the
interventionist implements the time delay trials.
The amount of time systematically increases
(e.g., from 1 to 2 s delay) until a terminal time
criterion is met. A second way to provide prompt-
ing in a time-based system is known as the con-
stant time delay prompting system. During initial
teaching with constant time delay, the interven-
tionist provides immediately prompted trials
(i.e., 0 s delay). After a set number of immediate
prompted trials or sessions, the interventionist
implements time delay trials (e.g., 5 s delay). In
time delay trials, the interventionist provides an
instruction to the learner (e.g., “Touch the ball”)
followed by a brief time delay, typically ranging
from 3 to 5 s, for the learner to respond to the
There are many other types of prompting sys-
tems which include graduated guidance (e.g.,
MacDuff, Krantz, & McClannahan, 1993),
simultaneous prompting (e.g., Leaf et al., 2010),
and no-no prompting (e.g., Leaf et al., 2010). The
aforementioned studies typically have strict rules
and protocols for interventionists to follow. In
contrast, ﬂexible prompt fading (FPF; Soluaga
et al., 2008) is a prompting system which does
not provide interventionists with strict protocols
of when to prompt and when not to prompt, but,
instead, provides guidelines. In doing so, the
interventionist makes changes based upon in-the-
moment assessment of several variables (e.g.,
current learner responding, affect, responses to
previous prompts; Leaf, Cihon, Leaf, et al. 2016;
Leaf, Leaf, McEachin, et al. 2016). Within FPF
the interventionist can use any and all prompt
types with the goal of keeping the learner averag-
ing 80% correct responding. In doing so, the
interventionist should always implement the least
assistive prompt whenever possible and fade
prompts as quickly as possible. To determine
what prompt to provide, the interventionist must
factor in many variables including the learner’s
history, recent responding, any undesired behav-
ior, length of teaching session, what prompts
typically have been successful, and what rein-
forcers are currently motivating.
Researchers have shown that FPF has been
successful in teaching receptive and expressive
labels (e.g., Soluaga et al., 2008). Soluaga et al.
(2008) provided the ﬁrst study to measure FPF in
which the researchers compared a time delay
prompt to FPF with ﬁve individuals diagnosed
with ASD. Time delay and FPF were effective,
but FPF was more efﬁcient. Additional studies
have shown that FPF was more effective than
most-to-least prompting (e.g., Leaf, Leaf,
Alcalay, et al. 2016) and error correction (e.g.,
Leaf et al., 2014).
J.B. Leaf et al.
Incidental teaching is a procedure commonly
used to expand language utilizing the principles
of behavior analysis. Incidental teaching has
been used to teach conversation skills (e.g., Hart
& Risley, 1975), play skills (e.g., Wong, Kasari,
Freeman, & Paparella, 2007), complex language
(e.g., Hart & Risley, 1978), social skills (e.g.,
McGee, Almeida, Sulzer-Azaroff, & Feldman,
1992), receptive labels (e.g., McGee, Krantz,
Mason, & McClannahan, 1983), and early read-
ing skills (e.g., McGee, Krantz, & McClannahan,
Hart and Risley developed incidental teaching
procedures in 1968 while working with children
from low-income families to increase the com-
plexity of their children’s language. Hart and
Risley (1975) deﬁned incidental teaching as “the
interaction between an adult and a single child,
which arises naturally in an unstructured situa-
tion, which is used by the adult to transmit infor-
mation or give the child practice in developing a
skill” (p. 411). Hart and Risley (1968) found that
the incidental teaching method expanded chil-
dren’s verbal communication skills and general-
ized into other settings.
Incidental teaching consists of four compo-
nents: (1) environmental arrangement, (2) child
initiation, (3) elaboration, and (4) reinforcement.
Incidental teaching should take place in the learn-
er’s natural environment, but the environment
should be arranged so that the learner needs to
initiate and request desired items, activities, and
any other materials (McGee et al., 1983).
Incidental teaching focuses on the learner’s inter-
ests and is dependent on the learner’s initiations.
Once the environment has been arranged appro-
priately, the interventionist should wait for the
learner to initiate. The nature of the initiation will
vary for each learner, which could be a gesture
toward an item or activity, a one-word request, a
manual sign, a full sentence, etc. The interven-
tionist may then target an elaboration of the
learner’s request. This could be in the form of a
question (e.g., “What color paint?”) or a vocal
model (e.g., “I want the giraffe”). The form of the
elaboration should also be individualized for the
learner. The goal is the learner then imitates the
expanded model or provides the expanded
response based on the prompt provided by the
interventionist. After the learner provides the
expanded response, the interventionist should
immediately provide the requested item/activity.
The requested item/activity should function as a
reinforcer and increase the likelihood of the
expanded vocal response occurring on future
Teaching language through incidental teach-
ing has several potential beneﬁts including
greater generalization compared to other proce-
dures, less prompt dependence, and a variety of
interventionists can easily implement the proce-
dure, including parents, teachers, and caregivers
(McGee, Krantz, McClannahan, 1985, 1986;
McGee, Morrier, & Daly 1999).
A token economy is a type of reinforcement sys-
tem in which the interventionist provides some
form of tokens (e.g., check marks, points, stick-
ers) contingent upon the learner engaging in a
targeted response(s). Once the learner earns
enough tokens, she/he exchanges the tokens for a
preferred item or activity (e.g., toy, edible, game)
which presumably functions as a reinforcer.
Since the acquisition of tokens is paired with the
delivery of a preferred item or activity, the tokens
function as a conditioned reinforcer. This is con-
sidered as a bridge in the gap to reinforcement as
the delivery of tokens marks the occurrence of
the desired behavior, but no preferred item or
activity will be accessed until the learner has
acquired a certain number of tokens. The applica-
tion of token economies has a long history in
research and clinical practice within the ﬁeld of
Ayllon and Azrin (1965) conducted a seminal
study in which they used a token economy to
evaluate the effects of extrinsic reinforcement on
behavior that was presumed to be intrinsically
motivating. The study consisted of six experi-
ments examining the effects of a token economy
and other operant procedures on the behavior of
An Introduction to Applied Behavior Analysis
adult patients, identiﬁed as psychotic, who
resided in a state hospital. The researchers imple-
mented a token economy throughout all six
experiments in which tokens could be exchanged
for privacy, leave from the ward, social interac-
tion with staff, devotional opportunities, recre-
ational opportunities, and commissary items. The
dependent variables across the six experiments
were selection and engagement in various jobs
inside and outside of the hospital. The contingent
application of the token economy system effected
choice of job as well as the patient’s performance
on the job.
Since Ayllon and Azrin’s (1965) seminal study
using a token economy, there have been several
investigations across multiple populations (e.g.,
developmental disabilities; Harchik, Sherman, &
Sheldon, 1992; juvenile delinquency; Phillips,
1968) and targeted responses (e.g., decreased
symptoms of depression; Hersen, Eisler, Alford,
& Agras, 1973; increased activity levels for
chronic pain patients; Ritchie, 1976) on the
implementation of token economies. In one
study, Charlop-Christy and Haymes (1998) eval-
uated two variations of token economies for three
individuals diagnosed with autism. One variation
used the participants’ perseverations as tokens
(e.g., if the perseveration was cars, then small toy
cars were used as tokens). The second variation
used stars as tokens. The percentage of correct
responding during performance tasks was higher
when perseverative objects were used as opposed
to stars. In a more recent study, Dotson, Richman,
Abby, Thompson, and Plotner (2013) evaluated a
class-wide token economy paired with the teach-
ing interaction procedure to teach job-related
skills to eight adults with various developmental
disabilities (e.g., intellectual disability, Down
syndrome, and autism). The combination of the
two procedures was successful in improving the
work-related behavior for all participants.
The research on token economies has helped
lead to the procedures widespread clinical use.
There are some variables that clinicians should
consider when implementing a token economy
that are worth noting. First, as with any reinforce-
ment system, what behavior will be reinforced
through the token economy must be determined.
Second, the form tokens will take must be
selected (e.g., points, stickers, check marks).
Third, which preferred activities will be available
for exchange (e.g., toys, breaks, social praise,
edibles). Fourth, how many tokens must be
earned before an exchange can occur. Fifth, if
tokens can also be lost (i.e., response cost;
described later); sixth, how to fade the token sys-
tem; and, ﬁnally, how the token economy will be
introduced should be planned. The ﬁnal decision
can often be the most important decision as prop-
erly introducing the token system is essential for
its success. Leaf, McEachin, and Taubman (2012)
have provided training materials on how to intro-
duce the token economy. Leaf and colleagues’
recommendation is to start with delivering tokens
for a simple behavior (e.g., the learner placing his
or her hands in the lap) and gradually expanding
in complexity. Additionally, Leaf and colleagues
recommended starting with the learner initially
only earning one token and then expanding to
more tokens before an exchange occurs. After
these decisions have been made by the clinician,
she/he can begin to implement the token
Another procedure which can be utilized to
reduce the rate of undesired behavior is response
cost. Response cost consists of the removal of a
reinforcing event contingent upon demonstration
of an undesired behavior. This procedure is com-
monly used within a token economy (described
earlier) in which the interventionist removes
tokens (e.g., points, stickers); however, response
cost can occur in the absence of a token system
(e.g., removing certain tangible reinforcers con-
tingent upon the learner engaging in an unde-
sired behavior). Phillips et al. (1971) conducted
a seminal study in which the researchers evalu-
ated the effectiveness of a response cost system.
In their study, all participants were part of
Achievement Place, a community-based treat-
ment facility, and were considered predelinquent
youths. All youths participated in a token econ-
omy, in which participants could earn points for
J.B. Leaf et al.
engaging in appropriate behavior and exchange
points earned for various reinforcers (e.g.,
snacks, TV, allowances). Within this study, the
researchers showed that a token economy with
response cost could increase punctuality for
meetings and answering questions correctly
about an event that was just observed (e.g.,
watching the news). Since this study, there have
been many evaluations of response cost which
have included evaluating response cost with typ-
ically developing individuals (e.g., Tiano,
Forston, McNeil, & Humphreys, 2005) and indi-
viduals diagnosed with attention deﬁcit hyperac-
tivity disorder (ADHD; e.g., McGoey & DuPaul,
2000), intellectual disabilities (e.g., Myers,
1975); ASD (Jowett, Dozier, & Payne, 2016),
developmental disabilities (e.g., Piazza, Fisher,
& Sherer, 1997), and emotionally disturbed
learners (e.g., Sprute & Williams, 1990).
Before a clinician uses response cost, there are
several considerations that must be taken into
account. First, decide if response cost will be
paired with systematized reinforcement system
such as a token economy. Second, decide what
behavior will result in a loss. Third, decide on the
cost (e.g., loss of a speciﬁc duration of time, loss
of three tokens versus one token). This is an
important consideration, as the clinician needs to
ensure that the cost is high enough to have an
effect on the target behavior, but not too great
resulting in prolonged lapses in engaging in
appropriate behavior. Finally, decide if the con-
tingencies will be discussed with the learner
before implementation. If the learner has the pre-
requisite skills required, discussing the system
with the learner may result in faster behavior
change. However, for some learners, discussing
the contingencies may not be appropriate and
should be avoided.
Differential reinforcement procedures are com-
mon for developing new behavior and decreasing
the probability of undesired behavior. Broad deﬁ-
nitions of differential reinforcement vary from
“reinforcing one response class and withholding
reinforcement for another response class”
(Cooper et al., 2007, p. 470) to “provide the
strongest reinforcers for the best behaviors or
performance” (Leaf & McEachin, 1999, p. 34).
Differential reinforcement procedures have dem-
onstrated effectiveness across a wide variety of
populations and target behaviors. Four common
differential reinforcement procedures include
differential reinforcement of other behavior
(DRO), differential reinforcement of low rates of
behavior (DRL), differential reinforcement of
incompatible behavior (DRI), and differential
reinforcement of alternative behavior (DRA).
DRO Within DRO, a reinforcing event is deliv-
ered contingent on the absence of a speciﬁc
topography of response (Reynolds, 1960; Weiher
& Harman, 1975). The delivery of the reinforcing
event occurs based upon the absence of the tar-
geted response for a speciﬁed duration of time or
if the targeted response is not occurring at a spec-
iﬁed time. There are several distinctions among
DRO procedures based upon how the delivery of
the reinforcing event is determined that are
beyond the scope of this chapter (see Cooper
et al., 2007 for a detailed description). The effec-
tiveness and variables affecting the effectiveness
of DRO procedures have been well documented
within the research literature.
For instance, in a recent study, Heffernan and
Lyons (2016) examined the effectiveness of a
DRO procedure to decrease the frequency of nail
biting for a 4-year-old boy diagnosed with ASD.
Prior to the onset of intervention, the researchers
conducted a functional behavior assessment
(FBA) and a preference assessment. Heffernan
and Lyons identiﬁed several items that may pro-
vide similar sensory feedback to nail biting (e.g.,
containers of dry rice and pasta to run his ﬁngers
through) that could potentially serve as reinforc-
ers. Initially, the preferred items were available
following 20 s without nail biting. The interval
was reset each time nail biting occurred. The
intervention was successful at decreasing the fre-
quency of nail biting and, throughout the course
of the intervention, the interval was increased to
An Introduction to Applied Behavior Analysis
60 min. For a detailed review of recent applied
literature utilizing DRO procedures, we refer the
reader to Jessel and Ingvarsson (2016).
DRL Ferster and Skinner (1957) ﬁrst described
DRL as delivering a reinforcing event contingent
upon the lapse of a minimum amount of time
without the occurrence of the target behavior and
subsequent increasing of the periods of time
between responses to further reduce the target
behavior. Another variation of DRL may also
involve a predetermined criterion level of
responding that must not be exceeded during a
speciﬁed timeframe to receive access to a rein-
forcing event (e.g., no more than three occur-
rences of a target behavior in 10 min regardless
of the time between responses). Thus, DRL may
not completely suppress the targeted response but
rather work toward systematically decreasing the
target behavior to more appropriate or acceptable
levels. Since Ferster and Skinner’s ﬁrst descrip-
tion, the DRL procedure has been utilized clini-
cally and evaluated empirically within the
In one example, Austin and Bevan (2011)
used a DRL procedure to reduce the frequency of
requests for interventionist attention with three
young children in an elementary school class-
room in South Wales. Baselines were taken for
all three participants to determine individual tar-
get rates. To begin each session, boxes signifying
the number of times the participant could request
attention were outlined on an index card, plus one
additional box. For instance, if the targeted rate
was three, that participant had four boxes on her
index card. Each time the participant requested
attention, a box was checked. At the end of each
session, the interventionist delivered a reinforcer
if the participant requested interventionist atten-
tion less often than the targeted rate (i.e., if all the
boxes were not checked). The results of a reversal
design showed that the DRL was effective at
decreasing the rate of requests for attention for all
DRI DRI differs from the DRO in that it speci-
ﬁes the response topography upon which the
delivery of reinforcement will be contingent.
Within this procedure, reinforcement is contin-
gent upon the occurrence of a predetermined
response topography that is incompatible with
the undesired behavior that is targeted for
decrease, however, not necessarily functionally
equivalent. For example, if head hitting with
one’s hand is the undesired behavior, hands in lap
or in pockets could be selected for reinforcement
because they are incompatible with head hitting.
Recent reviews of the empirical literature have
shown that DRI procedures are less common
among differential reinforcement procedures and
that positive treatment effects are commonly only
observed when the DRI is paired with other pro-
cedures (Chowdhury & Benson, 2011).
For example, Neufeld and Fantuzzo (1987)
examined the effectiveness of a DRI procedure to
decrease the frequency of self-injurious behavior
(SIB) for three adults at a state hospital. The
incompatible behavior selected during the inter-
vention was placing rings onto a peg which was
related to the participants’ current habilitative
programming and incompatible with the
SIB. Reinforcement was delivered at 10 s inter-
vals for engaging in the incompatible task. This
DRI procedure was only partially effective as the
rate of SIB still occurred at variable rates across
all three participants. However, when paired with
contingent application of a helmet in combina-
tion with the DRI procedure, SIB was reduced to
near zero levels for all three participants.
DRA DRA is similar to the DRI in that it speci-
ﬁes a response upon which reinforcement is con-
tingent. However, unlike the DRI, the response
selected within the DRA is not necessarily
incompatible with the undesired behavior.
Consider the head hitting example used in the
description of the DRI above. Alternative
responses for head hitting that are not necessarily
incompatible with head hitting may be requesting
squeezes to the head, resting hand on the head, or
asking for a break. DRA and DRO procedures are
the most commonly used differential reinforce-
ment procedures used among the literature
(Chowdhury & Benson, 2011).
In one example within the literature, Rehfeldt
and Chambers (2003) utilized a DRA procedure
J.B. Leaf et al.
to decrease the frequency of perseverative verbal
behavior and increase the frequency of appropri-
ate verbal behavior for a 23-year-old male diag-
nosed with autism and mental retardation. There
was no single appropriate verbal response
selected for reinforcement; rather, all appropriate
verbal responses were candidates for reinforce-
ment. Attention and eye contact (presumed rein-
forcing events) were delivered contingent upon
engaging in appropriate verbal behavior. The
results indicated that the DRA procedure was
effective at increasing the frequency of appropri-
ate verbal behavior and decreasing the frequency
of perseverative verbal behavior.
While differential reinforcement is commonly
used for the reduction of the rates of undesired
behavior, it is also used to strengthen response
classes and is a key component of shaping
(described later). For an in-depth description of
the differential reinforcement procedures
described here, we refer the reader to Cooper
et al. (2007), Chowdhury and Benson (2011), and
Sulzer-Azaroff and Mayer (1977).
Time-Out from Reinforcement
Time-out from reinforcement is a procedure
which is used to decrease the rate of undesired
behavior. When implementing time-out, the
interventionist removes or delays reinforcement
for a certain period of time contingent upon the
learner engaging in undesired behavior. For
example, if one wants to reduce screaming while
playing a video game, one may pause or remove
the video game for a brief period of time. It
should be noted that time-out from reinforcement
does not necessarily mean moving an individual
from one area to another, as is commonly done in
mainstream society. Instead, time-out refers to
temporarily removing access to reinforcement,
the speciﬁcs of which are dependent on the nature
of the reinforcement.
In a seminal study, Bostow and Bailey (1969)
evaluated the implementation of a brief time-out
procedure to decrease undesired behavior for
residents in a large state hospital. A 58-year-old
woman, in a wheel chair, who engaged in fre-
quent loud vocalizations and swearing behaviors
participated in the ﬁrst experiment. The research-
ers implemented a 2 min time-out procedure plus
a DRI (described previously). The time-out pro-
cedure consisted of moving the participant to the
corner of the room and placing her on the ﬂoor.
The results of the study showed that the time-out
procedure resulted in an immediate change in the
participant’s behavior, with loud vocalizations
occurring at near zero rates. The same procedure
was used in the second experiment with a 7-year-
old boy who engaged in frequent aggressive
behavior. The results replicated those from the
ﬁrst experiment with the rate of aggression
decreasing immediately and occurring at near
zero rates. Since this study, there have been
numerous investigations of time-out to decrease
the severity of aberrant behavior across various
populations including typically developing chil-
dren (e.g., Miller & Kratochwill, 1979), individu-
als diagnosed with ASD (e.g., Donaldson &
Vollmer, 2011), individuals diagnosed with atten-
tion deﬁcit disorder (ADD) and ADHD (e.g.,
Fabiano et al., 2004), individuals diagnosed with
developmental disabilities (e.g., Mace & Heller,
1990), and individuals diagnosed with intellec-
tual disabilities (e.g., Ritschl, Mongrella, Presbie,
There are several variables for clinicians to
consider before implementing a time-out proce-
dure. First, deﬁne what behavior will result in
time-out from reinforcement. In considering this,
the function of the behavior is important. The cli-
nician must ensure that the learner is not placed
in a time-out when the function of the behavior is
to escape their present environment, as this would
have the opposite effect and would likely rein-
force the behavior. Second, and perhaps most
importantly, the clinician must ensure that the
time-in environment is reinforcing. If the time-in
environment is not reinforcing, then the cost for
leaving that environment will not result in the
desired behavior change. Third, decide the dura-
tion of time-out. Research on the amount of time
a learner remains in time-out has been mixed
with some studies showing that a shorter duration
is more effective (e.g., Pendergrass, 1971) and
some studies showing a longer duration is more
An Introduction to Applied Behavior Analysis
effective (e.g., White, Nielsen, & Johnson, 1972).
Fourth, decide the criteria for leaving time-out
(e.g., waiting for the learner to refrain from
engaging in undesired behavior). Fifth, decide if
time-out is to be exclusionary (i.e., the individual
removed from all elements of the environment)
or non-exclusionary (i.e., only partial elements of
the environment removed). It is very important to
ensure that all state laws, federal laws, and ethi-
cal codes are being followed in making such
decisions. Finally, decide what procedures (e.g.,
differential reinforcement, token economies,
prompting) to implement in conjunction with
time-out to ensure that the individual learns
appropriate replacement behaviors.
Shaping is usually described as differentially
reinforcing (described previously) successive
approximations toward a terminal response or
goal (e.g., Cooper et al., 2007; Skinner, 1953).
This leads to the common view that shaping is a
linear process in which the reinforcement of an
approximation leads to another and another until
the terminal response is obtained. For instance,
when using shaping to improve upon selective
eating, it is common to develop a set of steps
leading to consumption of a food (e.g., touch,
pick up, move toward mouth, touch to lips, hold
between teeth, bite down, chew, swallow).
However, others have described the shaping pro-
cess as a method to expand general response
classes, which, in turn, provide the shaper with
more responses from which to select and the
learner with more responses in which to engage
(Bernal, 1972; Cihon, 2015). Take the aforemen-
tioned approach to address food selectivity as an
example. A nonlinear shaping approach, such as
Bernal (1972), would focus on expanding critical
classes of responding (e.g., tolerating, interact-
ing, tasting). Shaping is frequently used within
practice and evaluated empirically to develop or
expand upon a number of response classes.
In a classic demonstration, Wolf et al. (1963)
used shaping to teach a 3-year-old boy to wear
glasses. The researchers started by placing empty
frames (i.e., without lenses) around the room
which, if the boy picked up, held, or carried the
frames, a reinforcer would be delivered.
Reinforcement was then delivered for bringing
the frames closer to his eyes. Once the boy was
putting his glasses on independently, the pre-
scription lenses were introduced. Reinforcement
was gradually faded, and the boy wore his glasses
for approximately 12 h each day. Ricciardi,
Luiselli, and Camare (2006) provided a more
recent demonstration in which shaping was used
to increase the frequency of approach responses
to electronic animated ﬁgures (e.g., dancing
Elmo® doll) with an 8-year-old boy diagnosed
with autism. Preferred items were available for
maintaining the targeted distance from the ani-
mated ﬁgures. The distance started at 6 m and
gradually increased in steps to 1 m from the ﬁg-
ures. The criterion distance was decreased upon
success with staying within the criterion distance
for 90% of intervals across two consecutive ses-
sions. The results showed that the shaping proce-
dure was successful at increasing approach
responses to previously avoided electronic ani-
Teaching Interaction Procedure/
Behavioral Skills Training
Two procedures that use instruction, modeling,
practice, and feedback to teach a wide variety of
skills are behavioral skills training (BST;
Miltenberger, 2012) and the teaching interaction
procedure (TIP; Phillips, Phillips, Fixsen, &
Wolf, 1974); however, some components between
the two procedures differ. BST begins with the
interventionist outlining the components of the
targeted skill. The interventionist provides a
model during or after this instruction. Following
the model, the learners are provided with an
opportunity to practice. The interventionist pro-
vides feedback during or after the practice. A TIP
begins with the interventionist labeling and iden-
tifying the skill. Next, the interventionist pro-
vides meaningful rationales, followed by
breaking the skill down into smaller steps (i.e., a
task analysis of the targeted skill). The interven-
J.B. Leaf et al.
tionist then demonstrates the correct and incor-
rect way to engage in the targeted skill. Following
this demonstration, the learner is provided with
opportunities to identify why the demonstration
was correct or incorrect. Next, the learner prac-
tices the targeted skill, while the interventionist
provides feedback. This last step continues until
the learner meets a speciﬁed criterion. The over-
lap of the components within BST and the TIP
often leads to confusion (Leaf et al., 2015). The
differences have been discussed at length else-
where (e.g., Leaf et al., 2015) and will not be dis-
cussed here; however, the authors encourage
interested readers to look at the corresponding
BST and the TIP have been well documented
to teach a wide variety of skills to a wide variety
of learners. For instance, Gunby and Rapp (2014)
used BST to teach three children (ages 5–6 years)
diagnosed with autism to engage in behavior to
prevent abduction from strangers. The interven-
tion consisted of (1) a discussion of the safety
response and potential lures, (2) video models of
potential scenarios and safe responses, and (3)
opportunities to practice the safety skills, fol-
lowed by (4) feedback based on practice opportu-
nities (corrective and reinforcing). The skills
were also probed within a high probability
instructional sequence for each participant. A
multiple baseline across participants showed that
BST was effective for teaching abduction preven-
tion skills for all three participants.
In another recent evaluation, Ng, Schulze,
Rudrud, and Leaf (2016) examined the effective-
ness of a modiﬁed TIP to teach four individuals
(9–15 years old) diagnosed with an ASD various
social skills. At the time of the study, each par-
ticipant had an IQ score less than 75. Targeted
social skills included providing help, negotiating,
giving a compliment, passing the phone, respond-
ing to offers of help, requesting without grab-
bing, and responding to comments. All teaching
sessions occurred in a small group instructional
format. The TIP was modiﬁed to include the use
of demonstrations of the rationales, picture
prompts for identifying situations in which to
engage in the skills, picture prompts to identify
the steps of the skills, and only providing demon-
strations of the correct way to engage in the tar-
geted skill to avoid the potential of imitating
undesirable examples. The modiﬁed TIP was
effective in teaching the targeted skills for all
The analog functional analysis methodology
developed by Iwata, Dorsey, Slifer, Bauman, and
Richman (1982, 1994) has become the standard
approach when it comes to assessing and treating
aberrant behavior. Iwata et al. (1982, 1994)’s
approach to treating aberrant behavior ﬁrst exper-
imentally manipulates antecedents and conse-
quences, in an analog setting, that may affect the
occurrence of aberrant behavior, determining the
function that maintains the aberrant behavior and
then proceeding to treatment based upon these
results. Once the function of the aberrant behav-
ior is determined, an intervention is developed to
teach a replacement behavior for the aberrant
behavior(s). It is common for targeted replace-
ment behaviors to be functional communicative
responses (e.g., Carr & Durand, 1985; Hanley,
Sandy Jin, Vanselow, & Hanratty, 2014) which
are commonly targeted using differential rein-
forcement, while the aberrant behavior is put on
extinction (Tiger, Hanley, & Bruzek, 2008).
To determine the likely function of aberrant
behavior, Iwata et al. (1982, 1994) used four ana-
log conditions which were systematically alter-
nated. Each condition manipulates antecedent
events that precede aberrant behavior and the
consequences that follow. The attention condi-
tion assesses if the aberrant behavior is main-
tained by social positive reinforcement. In the
attention condition, the therapist ignores the indi-
vidual while typically occupying themselves
with another activity (e.g., reading a magazine,
cleaning, etc.). Once the individual exhibits aber-
rant behavior, the therapist provides attention. In
the escape condition, the environment is arranged
to assess if negative reinforcement is the main-
taining function. In this condition, a task demand
is continually presented; if the individual engages
in aberrant behavior, the task demand is delayed
An Introduction to Applied Behavior Analysis
for a certain period of time. The alone condition
in an analog functional analysis is used to deter-
mine if the aberrant behavior is maintained by
automatic reinforcement. In the alone condition,
the therapist and any other materials are not pres-
ent in the room. Additionally, no programmed
consequences are provided contingent on aber-
rant behavior. The play condition serves as a con-
trol condition. Within the play condition,
attention is given noncontingently on a predeter-
mined schedule, no task demands are placed, and
free access to toys is available. Another condition
commonly used in an analog functional analysis
is the tangible condition. Similar to the attention
condition, the tangible condition is used to deter-
mine if positive reinforcement is the controlling
contingency. In the tangible condition, a pre-
ferred item and/or activity is present in the room
with the therapist which, contingent on aberrant
behavior, is provided to the individual (Rooker,
Iwata, Harper, Fahmie, & Camp, 2011).
Since the landmark Iwata et al. study (1982,
1994), research in the area of analog functional
analyses has become a staple within behavior
analytic research. Many different topics of
research have stemmed from the initial research
on the functional treatment of aberrant behavior
including descriptive assessments (Anderson &
Long, 2002; Lerman & Iwata, 1993; Touchette,
MacDonald, & Langer, 1985), anecdotal assess-
ments (Smith, Smith, Dracolby, & Pace, 2012;
Iwata, DeLeon, & Roscoe, 2013), brief func-
tional assessments (Bloom, Lambert, Dayton, &
Samaha, 2013), interview-informed synthesized
contingency analysis (IISCA; Hanley et al.,
2014), and functional analyses via telehealth
(Wacker et al., 2013).
Functional Communication Training
Functional communication training (FCT) is an
intervention in which appropriate communicative
behavior is taught as a replacement for aberrant
behavior (Cooper et al., 2007). For an FCT inter-
vention to be successful, a functional assessment
must ﬁrst occur to determine the function of the
aberrant behavior. After the function is deter-
mined, an appropriate communicative response
can be taught that serves the same function as the
For example, in Carr and Durand’s (1985)
hallmark study, four children with developmental
disabilities were taught desired requests for
escape from task demands (negative reinforce-
ment) or teacher attention (positive reinforce-
ment). Carr and Durand developed several
conditions to determine the social function of
each participant’s aberrant behavior (i.e., atten-
tion or escape from a demand). Once the func-
tions were determined, Carr and Durand identiﬁed
a communicative response that would serve as a
replacement behavior for each of the participant’s
aberrant behavior. To assess the importance of
functionally equivalent replacement behavior, the
experimenters taught each participant an irrele-
vant communicative response that did not result
in similar consequences to the aberrant behavior.
Functionally equivalent communicative
responses were taught through verbal prompts
and differential reinforcement. The aberrant
behaviors for each participant decreased once the
functional communicative response was taught
and the irrelevant communicative responses were
not effective in reducing aberrant behavior.
Since Carr and Durand (1985), FCT has been
used to reduce a wide variety of aberrant behav-
iors including aggression, self-injurious behav-
ior, vocal disruptions, property destruction,
elopement, body rocking, pica, and inappropriate
sexual behavior (Durand & Carr, 1991; Fisher
et al., 1993; Fyffe, Kahng, Fittro, & Russell,
2004; Hagopian, Fisher, Sullivan, Acquisto, &
LeBlanc, 1998; Wacker et al., 1990). FCT has
also been shown to be effective across a wide
range of populations including adults (Wacker
et al., 1990) and children diagnosed with
developmental disabilities (Durand & Carr,
1991), children with cerebral palsy (Durand,
1999), children with traumatic brain injury
(Fyffeet al. 2004), typically developing children
(Hanley, Heal, Tiger, & Ingvarsson, 2007), and
children diagnosed with autism (Sigafoos &
Meikle, 1996), among others.
When implementing FCT several variables
should be considered. First, the function of the
J.B. Leaf et al.
individual’s aberrant behavior should be identi-
ﬁed. This could be done through anecdotal
assessments, descriptive assessments, or experi-
mental functional analyses. After the function, or
hypothesized function, of the aberrant behavior is
determined, a functionally equivalent communi-
cative response should be selected.
Interventionists should consider response effort,
the speed of response acquisition, and if the
response taught will be recognized and rein-
forced in other environments (Tiger et al., 2008).
When teaching the functional communicative
response, the initial teaching location, the type of
prompting system, how to fade prompts, and how
to promote generalization should also be consid-
ered depending on the learner’s skill level (Tiger
et al., 2008). Finally, the interventionist should
decide if the aberrant behavior in question will be
put on extinction, if the aberrant behavior will be
reinforced during teaching, or if punishment will
be utilized (Tiger et al., 2008).
Chaining is a procedure used to teach new
responses by linking a sequence of discrete
responses together to form a new behavior
(Cooper et al., 2007). In a behavioral chain, each
discrete response produces a stimulus change
which then serves as a reinforcer for the response
that produced it and serves as a discriminative
stimulus for the next response in the chain
(Cooper et al., 2007). Chaining procedures have
been used to teach shoe tying for individuals
with ASD (Rayner, 2011), a sequence of dance
moves (Slocum & Tiger, 2011), janitorial skills
for individuals with intellectual disabilities
(Cuvo, Leaf, & Barakove, 1978), adding with a
calculator and accessing a computer program
(Werts, Caldwell, & Wolery, 1996), and swal-
lowing liquids (Hagopian, Farrell, & Amari,
1996), among many others.
To teach a behavioral chain, a task analysis of
the necessary steps in the chain must happen ﬁrst.
A task analysis involves breaking down a com-
plex skill (e.g., shoe tying) into smaller units in
sequential order (Cooper et al., 2007). In order to
ensure the task analysis is correct and complete,
the interventionist should validate the task analy-
sis by observing the completion of the task by
individuals who are ﬂuent with the task, consult-
ing experts, or performing the skill using the task
analysis (Cooper et al., 2007; Sulzer-Azaroff &
Teaching a behavioral chain is typically done
through forward chaining or backward chaining.
Forward chaining is when each response in the
behavioral chain is taught sequentially. For
example, if hand washing was taught through
forward chaining, then the ﬁrst step taught would
be turning the faucet on, then putting hands
under the water stream, pumping the soap on to
hands, rubbing hands together, etc. until hand
washing was completed. Backward chaining is
when the instructor completes the initial
responses in the behavioral chain except for the
terminal response in the behavioral chain.
Reinforcement is then delivered contingent upon
the learner completing this ﬁnal response. For
example, if backward chaining were used to
teach shoe tying, then the interventionist would
complete all the responses in the chain except for
the last step (i.e., pulling the bow tight). If the
learner pulls the bow tight, then reinforcement
would be delivered. The interventionist would
then teach the learner the second to last step in
the behavioral chain (i.e., pulling loop through).
The learner would then be responsible for com-
pleting the last two steps in the behavioral chain.
This process would be repeated until the learner
is completing all the responses in the behavioral
When using chaining procedures in a clinical
setting, there are several variables to consider, for
instance, the length of the behavioral chain and
length of the discrete responses. Depending on
the learner’s skill level, longer chains with more
complex individual responses may be too difﬁ-
cult for the learner to master (Sulzer-Azaroff &
Mayer, 1977). Utilizing responses already in a
learner’s repertoire, or closer to the learner’s rep-
ertoire, may lead to faster acquisition of a behav-
An Introduction to Applied Behavior Analysis
ABA has come a long way in the past 50 plus
years. Our forefathers (e.g., B.F. Skinner, Donald
Baer, Montrose Wolf, Todd Risley, James
Sherman, Ivar Lovaas, Sid Bijou, Ted Ayllon,
and Nate Azrin) and foremothers (e.g., Judith
Leblanc, Barbara Etzel, Sandra Harris, Beth
Sulzer-Azaroff, Rosalie Rayner, Mary Cover
Jones) laid a strong foundation of methodology
which can be used to develop desired behavior
and decrease undesired behavior. Today the num-
ber of professionals going into the ﬁeld of ABA
continues to rise (Carr, Howard, & Martin, 2015),
and the procedures based upon these principles
are implemented in a wide variety of settings
(e.g., home, school, clinic, university, residential,
hospital, and community settings). Although
many professionals in the ﬁeld of ABA work
with individuals diagnosed with ASD, ABA-
based procedures are effective for a wide variety
of populations. When the principles of ABA were
ﬁrst explored, they were being implemented with
juvenile delinquents (Phillips et al., 1971), typi-
cally developing individuals (Hersen et al., 1973),
and children with intellectual disabilities (Ayllon
& Azrin, 1968).
There is no question that the ﬁeld of ABA has
made tremendous improvements in the lives of
many individuals; however, there still remain
areas in which the ﬁeld may improve upon. For
instance, with the growing need for well-trained
behavior analysts, it is imperative that education
and training is thorough, ongoing, and compre-
hensive (Ellis & Glenn, 1995; Shook, Ala’i-
Rosales, & Glenn, 2002). As one can determine
based on the content of this chapter, ABA and its
applications are broad and require sophisticated
repertoires. Dependent upon the behavior ana-
lyst’s cliental, education and training should
include the relevant procedures described
throughout this chapter in addition to the princi-
ples of ABA, in-the-moment assessment, critical
thinking, clinical judgment, and problem
ABA is a broad ﬁeld with broad applications.
The procedures described in this chapter are sim-
ply an introduction to effective procedures in the
ﬁeld. These and many other procedures based
upon the science of ABA continue to make
socially signiﬁcant gains in the lives of individu-
als around the world. There is no doubt that the
ﬁeld of ABA will continue to make meaningful
contributions to society with a strong adherence
to the core principles of the science and contin-
ued development of meaningful solutions to soci-
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