https://docs.google.com/document/d/1_w-tmTtfPg5zsl..
Part I – Verbal Behavior
Hello everyone, in this module, we will take a look at how to teach verbal behavior.
We will specifically go over using Skinner’s analysis to teach different verbal operants with
motivating operations and discriminative stimuli.
Before we start discussing interventions, let’s review what verbal behavior is and what verbal
operants are. Verbal behavior is behaviors that are reinforced through social mediation. There
must be a listener whose responses would reinforce the behavior of the speaker. Different from
the linguistic view of language and form. Skinner’s verbal behavior focuses on the function of
the behavior and how the behavior is controlled by environmental variables.
Skinner has outlined the elementary verbal operants. They include mand, tact, duplic, codic,
and intraverbal.
Mands are evoked by motivating operations and are reinforced by the stimulus changes that
are related to the motivating operation. For example, if you are hungry, you would mand for
food. Hunger is the motivating operation, and you will receive food as the reinforcer.
Tacts are evoked by nonverbal stimuli. The stimuli could be visual, auditory, tactile, or in any
sensory inputs. Tacts are reinforced by generalized reinforcement. For example, if you are
having candy, you might say, “it is sweet.” In this case, you are tacting the taste of the candy.
Intraverbals are evoked by verbal stimuli. For example, when a question, “what is your name?”
is asked, you would respond by telling your name. Telling your name is an intraverbal evoked by
the verbal stimulus, the question. Note that there is no point-to-point correspondence between
the question and the intraverbal response.
Duplics are evoked by verbal stimuli such as an echoic model, a physical model, or texts. Duplic
responses are the same as the verbal antecedents. For example, when you model a behavior,
and the learner imitates, the learner’s imitation is a duplic. Similarly, when you say a word and
the learner repeats the word, the echoic response is a duplic. Likewise, if a learner copies a
paragraph word for word, copying text is a duplic. You should note that the verbal antecedents
and the duplics are exactly the same. They share point-to-point correspondence and are in the
same form.
The last elementary verbal operant is codic. Codics are those evoked by verbal stimuli and share
the point-to-point correspondence with the verbal stimuli. However, they are not in the same
form. For example, if you are decoding a written word – or a textual response – your decoding
response is evoked by the verbal antecedent and shares the point-to-point correspondence
with the written word. But decoding is in an auditory form, that is different from the written
word. Similarly, taking dictation also shares the point-to-point correspondence with the verbal
auditory antecedent, but they are not in the same form.
As with all skill-acquisition and behavior-reduction programs, you will need to conduct an
assessment to see how the learner’s current performance is. The norm-referenced assessments
should be able to identify where the delays are and compare the learner performance with the
performance of the norm, typically developing children. Several criterion-referenced
assessments, such as VB-MAPP and ABLLS, can further measure each of the verbal operants and
the listener behaviors. In this case, specific skill deficits can be pointed out.
Let’s take a look at how to teach mands. First, you need to assess the learner’s manding skills
under different motivating operations. For unconditioned motivating operation, such as
deprivation of certain reinforcers, can the learner request that reinforcer? For example, if a
learner has not had chips for a while, can the learner request for the chips?
For CMO-R, if the learner is under a worsening situation, such as a difficult task that they
cannot complete, will the learner mand for help?
For CMO-T, will the learner mand for a missing item to complete a task? These are just
examples of different mands under various MOs, you will need to assess more than these
forms.
Additionally, assessments should also identify if there are environmental variables that weaken
manding repertoire. If reinforcers are freely available, there would be no MO for manding to
occur. Likewise, if problem behavior produces reinforcement, you should consider teaching an
alternative appropriate mand for the reinforcement.
After you have identified the missing mands, you can start mand intervention. The first step in
the mand intervention is to identify the response form. Does the learner need to use speech,
sign language, or icon selection to mand for reinforcers?
If the learner already has speech and can produce one or multiple words, you can directly use
speech as the response form.
For nonvocal learners, you may need to select between icon selection and sign language. Icon
selection refers to the response of selecting an icon or picture and delivering the icon to a
person to receive the reinforcer as identified on the icon. One example of icon selection is the
Picture Exchange Communication System. It is easy to teach if you follow the steps and can be
easily understood by any listener. However, learners’ choices are restricted to the available
icons.
Sign language, on the other hand, can have a similar level of flexibility as the speech because
there are endless combinations of gestures for a variety of mands. They are not restricted to
the available icons.
However, for sign language to be effective, the learner must have fine and gross motor
movements to gesture these complex signs, and the listener needs to be able to respond to
these signs. For example, mands using sign language may not be understood by persons who do
not know signs.
Teaching mands usually follows the natural teaching strategies where MOs are captured or
contrived.
The basic instructional sequence is as follows: you will first capture or contrive the MOs, once
the learner demonstrates responses associated with the MOs, you can provide a prompt. As
soon as the learner mands upon the prompt, deliver the reinforcer.
Let me demonstrate using the UMO, CMO-R, and CMO-T.
For deprivation-based UMOs such as those for food items and beverages, you can present a
number of different items in front of the learner. As soon as you notice that the learner
demonstrates the responses associated with the MOs, for example, trying to grab or
approaching the juice box, conduct the manding trial by providing a prompt such as an echoic
prompt: “I want juice.” When the learner imitates the echoic model, provide the reinforcer, in
this case, juice box.
Remember that you need to capture the MO by identifying the responses that are associated
with MO, and the reinforcer should be related to the MO and specified in the mand.
You can also contrive or creating MOs. For example, you can place a glass of water next to the
learner and provide salty food items as the reinforcers during discrete-trial teaching. As soon as
the learner approaches the water, you can provide an echoic prompt and provide the water
after the learner mands for the water.
For CMO-R, you will have to capture or create a worsening situation, such as a difficult task or
any unpleasant events in the immediate vicinity of the learner. Let’s use heat as an example. If
the learner is running around and sweaty, they may approach the thermometer. In this case,
you can block the approach and use an echoic prompt, such as “turn the air down.” And then
turn the air down after the learner mands.
For CMO-T, you will need to prearrange and contrive motivation. For example, if your target
mand is “where” questions, you can hide the learner’s toy somewhere. When the learner
mands for the toy, you would tell the learner that you do not have it. And then provide an
echoic model using a “where” question. After the learner mands using the where question, you
can tell the learner where the toy is, but do not directly provide the toy. The learner should go
find the toy themselves. Remember, the reinforcer for the question, in this case, is the location.
Similarly, you can hide a piece of a puzzle and ask the learner to complete the puzzle. When the
learner starts to search for the missing piece, you can model the “where” question and let the
learner know where the missing piece is after they mand for the piece.
As you have probably noticed that the echoic models have been used in my examples in the
hope that control of mands can be transferred from echoic models to MOs. This is called the
echoic-to-mand transfer procedure. Sometimes, if a learner can already label the item, you can
also use a tact-to-mand transfer procedure. Using the tact-to-mand transfer procedure may
establish multiple controls of the verbal response. That is, the same response is controlled by
MO and the physical item.
Once the learner can reliably echo your models, you can start fading the prompt. You can
consider using a constant time delay procedure. You can withhold the reinforcer and wait for
the response from the learner for 5 seconds. If no response is emitted, you can provide the
prompt. If the stimulus is reinforcing enough, the echoic-to-mand transfer procedure can
rapidly promote independent mands without too many prompt-fading trials.
As with mand intervention, when you prepare for tact intervention, you will need to assess
tacts. That is, you will assess how many nonverbal stimuli can evoke verbal responses. This not
only includes naming or labeling the stimuli, but also include properties, prepositions,
pronounces, and adjectives. The assessment may be done across different sensory inputs, such
as visual, auditory, and tactile. They correspond to tacting what the learner sees, hears, and
feels.
As with mand intervention, tact intervention can also include different response forms
depending on the learner. They can include speech, sign language, and icon selection. For
example, while the Picture Communication Exchange System primarily targets mands, the last
phase of the system is to teach tacting. The learner needs to construct the sentences that start
with “I see.” For example, “I see a horse.”
If a learner has a strong echoic repertoire, an echoic-to-tact transfer procedure should be used.
Similar to echoic-to-mand transfer, you would use an echoic model. For example, after you
have shown the learner a picture of chocolate, and ask “what do you see,” you would
immediately say “chocolate” – the echoic model. Once the learner tacts correctly, you would
provide a reinforcer. Remember that the reinforcer should not be specified by the tact; in this
case, it should not be a piece of chocolate. Otherwise, you might be training mand. The fading
procedure could include a time-delay or most-to-least prompt fading procedure.
Similarly, for signing, you could use a physical model and then fade the model.
Alternatively, you could also use a mand-to-tact transfer, if the learner can reliably mand for
the target items. In this case, you would present a reinforcer and ask, “what is it?”. As soon as
the learner mands for it, for example, by pointing to and labeling the reinforcer, you would say,
“That’s right!” and then deliver the reinforcer initially. Later on, remember to eventually deliver
another reinforcer for the tact. Remember that you should not deliver the reinforcer specified
in the tact in the long term, because, in this case, you would be conducting mand intervention.
Teaching a learner to tact private events may need to rely on collateral public events. That is,
you will have to connect the dots to derive how the learner is feeling. For example, if a learner
accidentally bumps into the wall and cries, you can derive that the learner is feeling pain. In this
case, you can teach tacting “pain.” Of course, you may be teaching a verbal operant that is
under the control of both the sensory input and the motivation for the pain to be gone.
Likewise, if the learner is having a fever or is coughing, you can teach tacting “sick.” When you
program tacting private events, make sure that you identify and capture the moments when
you will be able to teach.
Duplic repertoire, the ability to duplicate the motor movements and sounds, serves as the basis
to teach various verbal operants. To assess duplic repertoire, you are actually assessing
generalized vocal and physical imitation. In other words, can the learner imitate your gross and
fine motor movements? Can the learner say what you say in the same speed and intonation?
Can the learner repeat the number of the speech sounds and motor movements you have
made?
In general, for nonverbal learners, you may want to start with imitation training to develop the
learner’s generalized imitative repertoire. The exact teaching procedure has been described in
the previous module. Once the generalized imitative repertoire has been developed, you may
be able to train the learner to use sign language if the echoic repertoire is still limited.
For intervention that promotes echoic repertoire, the most often used approach is shaping the
successive approximations to the echoic model. For example, if your echoic model is “ball,” you
would shape the verbal response from “ba” to “baaa” and then to “ball.” We have discussed
shaping in-depth previously. A speech-language pathologist also uses other tools to physically
prompt the learner to make correct lip and tongue positions.
Another method is to pair the echoic model with a reinforcer. That is, as soon as you provide an
echoic model, you deliver a reinforcer. With repeated pairing, the sound presented in your
model would become reinforcing, and the learner is more likely to produce that sound as a
result of automatic reinforcement. Once the learner starts to produce the sounds, you can
bring that sound under the control of the echoic model. For example, if the learner increases
the sound production, say the learner emits the target sound every 10 seconds, and you
present the echoic model frequently, the learner’s sound production that is emitted right after
your echoic model would produce direct reinforcement. In this case, you can bring the learner’s
sound production under the control of your echoic model. Shaping, in this case, should still be
used in order to develop various echoic responses.
As discussed in previous modules, the pairing procedure can be either contingent or
noncontingent. The contingent pairing seemed to have produced better results. In contingent
pairing, you would provide an echoic model with a known reinforcer upon a response. This
procedure seems to be more effective.
Last, you may also select a vocal response that the learner emits at a higher rate. In this case,
after the learner produces the vocal response, you would present the echoic model of the same
response. Due to the relatively higher rate of this response, the learner will likely produce the
sound again. A reinforcer is delivered if the learner produces the sound after your echoic
model. Thus, you are bringing the sound under the control of your echoic model.
Intraverbal assessment includes assessing simple verbal discriminations, compound verbal
discriminations, verbal conditional discriminations, and verbal function-altering effect. In simple
verbal discriminations, you will be asking questions with simple verbal stimulus. For example,
you may ask the learner, “what is your name?” “Tell me a fruit.” “Name an animal.”
In compound verbal discriminations, the antecedent verbal stimulus is a compound stimulus.
For example, you can ask, “can you tell me a big animal?” In this case, the compound consists of
big and animal.
Assessing verbal conditional discriminations requires you to present contrasting verbal stimuli.
For example, you may ask, “what is your name?” and then ask, “what is your mom’s name?”
The learner needs to respond according to the conditional verbal stimuli presented in the
questions.
Last, you can assess the verbal function-altering effect of a verbal stimulus. The effects are
usually delayed. For example, you can tell the learner to let their mom know that they did a
good job at school. You will then assess if the learner produces the verbal response when they
go home. In this case, the targeted intraverbal response is observed later in time.
Because it is difficult to train verbal responses that are under the control of verbal antecedents,
some have recommended delaying the intraverbal intervention until the learner has wellestablished mand, tact, echoic, imitation, receptive, and matching-to-sample repertoire. You
should also avoid teaching new verbal responses and target the verbal responses within the
learner’s existing repertoire first. For example, if the learner can readily say the word “apple,”
but cannot say the word “horse.” You should prioritize the intraverbal targets of “apple.”
Similar to mands and tacts, you can transfer stimulus control from a verbal operant to
intraverbal. For example, you may be able to use a mand-to-intraverbal transfer procedure or
using a mand frame. In this case, let’s assume that one of the learner’s reinforcers is orange
juice, and you want the learner to answer the question, “what do you drink?” You would
present orange juice in front of the learner and ask the question, “what do you drink?” As soon
as the learner answers, “orange juice.” You would deliver the orange juice initially. Over time,
you would fade the nonverbal prompt, the physical orange juice, and change the reinforcer to
another reinforcer.
You could also use an echoic-to-intraverbal transfer procedure. In this case, after you present a
verbal stimulus, you would immediately present an echoic model for the learner to imitate.
Tact-to-intraverbal transfer refers to the procedure that includes a tact prompt. For example,
after you present a verbal stimulus, “what is an animal?” You immediately present a picture
prompt of a cow. In this case, the learner would tact the picture. And through prompt-fading,
the control of the response will be transferred from the picture to the question.
Previous research on different prompts used in intraverbal training has shown idiosyncratic
results. Some showed tact prompts, and textual prompts produced better results than echoic
prompts while the other shows that echoic prompts were more effective. You may need to
assess the immediate reinforcement history of prompts. That is, which prompt has the learner
experienced previously and was effective? Among the prompts, the prompt that the learner is
exposed to more recently and more often may produce better effects.
You could also arrange a brief alternating-treatment comparison to assess the differential
efficiency of the teaching methods and see which is more efficient for the learner.
In general, the above teaching procedure can help improving simple verbal discriminations and
compound verbal discriminations. You would just need to modify your verbal antecedents by
either including simple or compound stimuli.
In the cases of verbal conditional discriminations, you may add a differential observation
response requirement similar to the ones that are required in conditional discrimination
training discussed previously. Some learners have difficulty differentiate the verbal conditional
stimuli, such as “what is your name?” and “what is your mom’s name?” Differential observation
responses would require the learner to repeat the question or a part of the question.
In verbal function-altering effect, an intraverbal should be emitted later in time. A mediating
stimulus that bridges the temporal distance may be necessary. For example, when you ask the
learner to tell their mom that they did a good job at school, you can have the learner hold a
notecard on which it says they did a good job when they go home. The notecard here mediates
the temporal distance in this case.
Alternatively, you could also start role-playing with no delay, and then gradually increase the
delay.
In daily speech, we also include secondary autoclitic behavior in addition to elementary verbal
operants. Autoclitics modify the effects of the speech on listener behavior. They require the
speaker to monitor and modify their own speech.
For example, when an individual makes a request for candy. To increase the effects of the
speech on the listener’s response or increase the likelihood of receiving the candy, the
individual could add “please.” Thus, it would be “I want candy, please.” “I want candy” is the
primary verbal behavior, the mand, and the additional “please” would increase the effects of
the mand. The word “please” in this case is the secondary autoclitic behavior. Because the word
“please” is also controlled by the MO, it is also called an autoclitic mand.
Similarly, in a sentence that states, “the answer is wrong, you need to believe me.” While “the
answer is wrong” seems to be a tact, when the latter part “you need to believe me” is added,
the entire speech becomes a mand. The latter part, “you need to believe me,” in this case, is an
autoclitic mand that modifies the effects of the speech on the listener. That is, ask the listener
to stop questioning.
There are also autoclitic tacts, which are controlled by the nonverbal stimuli. For example, in
the sentence, “as you can see, the data here have shown a decrease in trend.” The latter part is
a tact describing the decreasing trend. The first part, “as you can see,” also stresses the
nonverbal stimulus – data. It informs the listener of a feature – an increasing trend.
That said, it can be difficult to assess whether an autoclitic relation is controlled by an MO or a
nonverbal stimulus. For example, in the example of the decreasing trend, the speaker may very
well want to stop the listener from questioning the data by adding “as you can see.” If the MO
is the controlling variable, that secondary autoclitic behavior would be an autoclitic mand.
Autoclitics may also manifest as different intonations or slow or rapid speech. For example, for
a speech, “this is right,” if you add a pause before the word, “right.” “This is …. right.” You
would be modifying the effects of the speech by weakening the statement.
As this module focuses on intervention procedures, please carefully review the Verbal Behavior
Chapter in Cooper et al. to study more about autoclitic relations.
Before a learner acquires autoclitic repertoire, they must have some prerequisite skills. You
need to assess if their current verbal repertoire is sufficient enough to support secondary verbal
behavior. For example, can they use the primary verbal operants fluently?
Because autoclitics require the learner to edit their own speech, the learner must also be aware
of and listen to their own speech. Additionally, can the learner tact or describe their own verbal
and nonverbal behavior?
To assess if a learner has emerging autoclitic relations, you could assess if the learner places
stress on certain words, pauses before certain words, and incorporates different intonations. In
addition, you want to assess if the learner can add phrases to strengthen or weaken their
speech, such as “I think,” “I know,” “I believe,” and “I’m sure.”
Teaching autoclitic mand is similar to teaching mand. You would also start by capturing or
contriving MOs. For example, if a learner already has the skill to request physical items, and you
want to teach the phrase, “please.” Then after the learner has manded, you would model the
phrase, “please.” Once the learner adds “please” to the request, you would deliver the
reinforcer.
Similarly, you can also teach the learner to use a louder voice if the mand is ignored. When the
mand is ignored, it should further increase the MO. Manding with the louder voice would serve
the function of autoclitic mands to increase the effects of the mand on the listener. During the
intervention, you can model, or role-play the mand with a louder voice.
Developing autoclitic tacts may be more difficult. However, you should be able to capture
opportunities to teach autoclitic tacts. For example, after the learner has made a tact, you can
prompt the learner to elaborate on their response by asking, “are you sure,” “where did you
hear that from,” “do you believe that?” You can further model the autoclitic tact to the learner
if the learner does not respond to your prompts.
If a learner already demonstrates autoclitic behavior, for example, they might add “I think.”
Make sure that you reinforce the verbal behavior.
Alternatively, you can also arrange autoclitic tact contingencies. In this case, the trial would
begin with standard tact training. For example, show the learner a ball, and prompt the learner
to say, “I see a ball.” Then you should hide the ball and drop the ball and let the learner hears
the sound, and then prompt the learner to say, “I hear a ball.” In this case, “I see” and “I hear”
indicate secondary autoclitic behavior.
Because listener behavior is a vital component in verbal behavior, we will cover the listener
intervention briefly. Most of these interventions have already been presented previously.
We have previously discussed how to teach simple verbal discriminations. Simple verbal
discriminations are tasks such as following instructions. For example, ask the learner to stand
up. You would typically use a discrete-trial arrangement with physical prompt or modeling as
well as reinforcement and error correction to teach the task.
Auditory conditional discriminations are tasks such as the receptive selection of items. For
example, you would place three comparison stimuli on the table and present a verbal sample
stimulus and have the learner select a comparison stimulus.
Compound verbal discriminations include verbal antecedents with multiple stimuli that control
behavior. For example, if you provide a direction, “go to the table.” This is a compound verbal
stimulus. The learner is required to discriminate the action – go, and the physical stimulus – the
table. Similarly, you can ask the learner to point to a finger. The learner needs to identify the
action and the finger in order to perform the correct response.
Verbal conditional discrimination training is similar to auditory conditional discrimination
training. It is accomplished by teaching the learner to respond to different aspects of the same
item according to the verbal conditional stimuli. For example, you can present a picture of a
zoo, and ask a bunch of questions such as “which animal has a long neck?” “Which animal has a
long nose?” “Who says ‘moo.'” In this case, the picture does not change, but the questions do.
And the learner needs to listen to the questions, identify the relevant features in the picture,
and answer the questions.
Another example is that you can show the learner a picture of an airplane and ask the learner
questions about its function, feature, and class. Learner’s response will depend on your
question.
The last is training the learner to respond to verbal stimuli at a later time. Or, more behaviorally
speaking, the verbal stimuli would change the function of future nonverbal stimuli. For
example, you can ask the learner to show something to their parents when they go home. The
function of nonverbal stimuli – parents, are changed to evoke the “showing” response.
Similar to the intraverbal intervention, you can train the learner to respond with a mediating
stimulus, such as written notecard. Alternatively, you can gradually increase the delay.
Part II – Collaboration
In the second part of this module, we will take a look at collaboration.
Specifically, we will address collaboration with others who support and/or provide services to
clients.
In clinical practice, you will commonly collaborate with other professionals, such as speechlanguage pathologists and medical professionals. Collaboration is the interaction between
professionals during service delivery with a common goal to improve student outcomes. It is
shared decision-making between the professionals. For example, if a learner has a limited
echoic repertoire and you are having difficulty in improving their accurate speech sound
production, you may collaborate with a skilled speech-language pathologist. Together, you will
determine the goal and provide recommendations as to how to improve the learner’s echoic
repertoire.
One common form of collaboration is behavioral consultation. It is typically conducted between
a behavior analyst, psychologist, or other specialists and a teacher or parents.
It typically includes four stages. The first stage is to identify the problem. It can be achieved
through an interview, in which the teacher or the parents will indicate the desired outcome for
the learner. For example, the parents may identify reading fluency and comprehension as the
desired outcome. In this case, the specialists and the parents or the teacher will identify the
discrepancy between the current and the desired levels of performance. For example, how
many words per minute can the learner read currently, and how many words per minute
should the learner be reading at?
In the next stage, the problem needs to be analyzed by identifying variables for solving
problems and developing plans. For example, what are the evidence-based interventions for
reading fluency? Can the environmental variables support the intervention? If so, how would
we approach the problem? Based on the existing literature, you may design a reading fluency
intervention program.
After problem analysis, treatment can be implemented. Treatment integrity should be ensured.
Last, based on the data collected during treatment and interview with the teacher and parents,
evaluation should be conducted to assess if treatment has improved the learner outcome and
whether treatment should be continued, revised, or terminated.
To achieve effective interdisciplinary collaboration, it is recommended to include strategies that
bring everyone on board. This includes all service providers, caregiver, and maybe the client
themselves. This requires a system of regular communication through email, in-person or
remote meetings. During the meetings or emails, a set of questions should be answered by the
members of the treatment team. These questions should address behavioral, health, and
intervention changes.
In the case of an intervention change, all members should be educated about the change. For
example, what is the change, and what does the change do? All interventions and the changes
should be monitored. Behavior analysts can take the lead by providing a visual display with
continuous data collection.
With the information on the intervention changes, you need to focus on two questions. Are the
changes evidence-based? And are the changes compatible with other interventions in the
treatment plan?
You may be able to consult with the professionals concerning the evidence of the intervention,
and data collected from the client should also be used to determine the evidence base.
Compatibility is the degree to which the intervention change is compatible with the goal and
the methodologies of other interventions. If the goal of the change is to promote positive
outcomes and is in line with the goals that were previously agreed upon by the treatment team.
The goal is compatible.
In terms of compatibility of methodologies, is it possible to implement both interventions
concurrently and does the implementation of one intervention interfere with the other? For
example, if the pharmacological treatment changes motivation, then it may not be compatible
with behavioral interventions.
If the intervention change suggested by other professionals is evidence-based and is compatible
with existing intervention, you should continue the universal strategies as described previously
with regular meetings and updates.
If the intervention change is evidence-based but incompatible with existing treatment, the
intervention team must determine which intervention should be tried first. For example, if a
learner manifests problem behavior and medication reduce the problem behavior. The
medication may not be compatible as it cancels out the effects of the other treatment. The
treatment team may decide to implement behavioral intervention first. The decision can be
based on client preference and analysis of the pros and cons of the intervention
implementation.
If the intervention is not evidence-based but is compatible with the current intervention, you
can either advocate that the intervention not be implemented or continue with regular
meetings and updates. That said, you should conduct an analysis of the pros and cons of the
intervention. If the intervention may be harmful or will take time away from evidenced-based
practice, you should advise against the intervention.
Last, if the intervention is not evidenced-based and is incompatible with the current
intervention, you need to recommend not to implement the intervention.
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