Incorporate Motivating Operations and Discriminative Stimuli Into Behavior-Change Procedures
If you’ve ever sat in supervision and heard a clinician say, “The reinforcer isn’t working,” you’ve probably wondered what’s really going on. Often, the issue isn’t the reinforcer itself—it’s that motivating operations and discriminative stimuli aren’t aligned. These two foundational concepts shape every intervention you design, from mand training to classroom behavior management. Yet they’re frequently confused, misapplied, or overlooked.
This article walks you through what motivating operations and discriminative stimuli actually do, how they interact, and how to use them ethically and effectively in your clinical work. By the end, you’ll recognize when an intervention is weak because motivation is low, and you’ll know how to signal to your learners when reinforcement is available.
One-Paragraph Summary
A motivating operation (MO) is an environmental event that temporarily changes how much a consequence is worth right now and affects how often a learner tries to get it. A discriminative stimulus (SD) is a cue that signals, “Reinforcement is available if you do this behavior.” Together, they form the antecedent side of the ABC framework. MOs set the stage for motivation; SDs set the stage for specific responses. Effective behavior-change procedures address both: you can’t rely on an SD to cue a response if the learner doesn’t want what’s being offered, and you can’t harness motivation if the learner doesn’t know when reinforcement is available. The practical steps include identifying relevant MOs, designing clear SDs, choosing reinforcers that match current motivation, and planning carefully to phase out support while maintaining ethical safeguards.
Clear Explanation of the Topic
What Is a Motivating Operation?
An MO is an environmental variable that changes two things at once: how much a reinforcer is valued right now, and how often behaviors that produce that reinforcer occur. Think of a learner who usually ignores crackers. Put that learner in a structured snack time when they haven’t eaten lunch, and suddenly crackers become wildly valuable. That shift is an MO at work.
Every MO has two effects. The value-altering effect makes a consequence more or less desirable. The behavior-altering effect makes all behaviors linked to that consequence more or less likely. When you’re hungry, food becomes more valuable—and you’re also more likely to ask for it, work for it, or reach toward it.
What Is a Discriminative Stimulus?
An SD is a cue—something the learner sees, hears, or feels—that signals, “If you do this behavior right now, reinforcement will happen.” It’s not the reinforcement itself; it’s the signal that reinforcement is available.
When a teacher holds up a visual schedule, that schedule is an SD. When you open a cabinet and see your favorite snack, that visual presence is an SD. The learner’s history with that cue and the reinforcement creates the control.
The power of an SD is that it increases the probability of a response before the learner has to try. The SD doesn’t make the behavior happen; it makes the behavior more likely because the learner has learned that this cue means “the contingency is in effect.”
How MOs and SDs Are Different
The distinction is simple but crucial. An MO changes how much something is wanted. An SD signals when it’s available.
You can have a powerful SD—a crystal-clear cue—but if motivation is low, the learner won’t respond. You can also have high motivation (your learner is hungry), but without an SD, they may not know when or how to access food.
Many clinicians accidentally mix these up. A parent might say, “My child doesn’t respond to praise,” when the real issue is that praise isn’t a strong reinforcer right now for that learner (an MO problem), not that the child doesn’t understand the cue (an SD problem).
Types of Motivating Operations
Motivating operations come in two broad categories. Establishing Operations (EOs) increase the value of a reinforcer and make approach-seeking behaviors more likely. Hunger is an EO for food; boredom is an EO for stimulation.
Abolishing Operations (AOs) decrease the value of a reinforcer and reduce corresponding behaviors. Eating a big meal is an AO for food; being tired can be an AO for active play.
Understanding whether your learner is in an EO or AO state guides your choice of reinforcers and timing. You can’t effectively teach manding for crackers when your learner is fully satiated, because the AO is in effect. Catch them before lunch, and the EO creates a natural teaching moment.
How MOs and SDs Interact in Real Time
Here’s where the practical complexity shows up.
Imagine a learner sitting at a desk with a red card in front of them. The red card is an SD: it signals that the teacher will provide help when the learner raises their hand. But what if the learner doesn’t want help? What if they’re confident in the task and don’t need support? The SD is there, clear as day, but the MO is low. The learner won’t raise their hand.
Conversely, imagine a learner who desperately wants help (high MO), but there’s no cue signaling when it’s available. They might whine, grab the teacher, or act out—all behaviors associated with getting help—but they don’t have a clear, trained response because the SD was never established.
Both matter. Both must be present for efficient, clean behavior change.
Why This Matters
Better Prediction and Control
When you understand MOs and SDs, you stop being surprised by inconsistent behavior. If a learner mands for food in one context but not another, you can assess whether the MO is different (are they hungry in one setting but not the other?) or whether the SD is different (is the cue visible in one setting but not the other?). This clarity lets you troubleshoot quickly and avoid wasting time on interventions that miss the real problem.
Avoiding Ineffective Interventions
A learner’s behavior won’t change if you’re using a reinforcer they don’t currently want. A student might sit through an entire reading lesson without complying—not because they don’t understand the task, but because the consequence is unmotivating.
Or a young child might fail to respond to a visual schedule (an SD) because no one ever paired that schedule with reinforcement, so it never signaled anything to them.
Over-relying on SDs without addressing motivation creates what clinicians call brittle behavior change. The learner responds in the training setting when the cue is obvious, but skills don’t generalize. Once you remove the SD or change contexts, the behavior collapses.
Ethical Practice and Client Dignity
Manipulating MOs without care can become coercive and harmful. Creating artificial deprivation—withholding food, access to preferred people, or comfort items to force compliance—violates basic ethical principles.
Conversely, understanding MOs ethically means recognizing natural motivations (hunger at snack time, desire for social connection, curiosity) and building interventions around them rather than against them.
When you design interventions that respect current motivation and use truthful, clear SDs, you’re building a relationship of trust and predictability. The learner understands the contingency. They’re not being tricked or pushed into a corner.
Key Features and Defining Characteristics
Motivating operations are defined by their ability to alter the value of consequences and change the frequency of behavior associated with those consequences. They’re momentary—they fluctuate based on deprivation, satiation, context, and emotional state. An MO is not a prompt, and it’s not a consequence; it’s an antecedent that affects how much the learner wants something.
Discriminative stimuli are defined by their function: they signal that a reinforcement contingency is in effect. An SD must be consistently paired with reinforcement to develop its controlling power. If you use an SD but don’t deliver reinforcement when the behavior occurs, the stimulus stops functioning as an SD and becomes merely a neutral cue.
A critical boundary: an SD without available reinforcement is not an SD. It’s just a stimulus. If you tell a learner, “Raise your hand and I’ll help,” but then ignore their raised hand, hand-raising stops being controlled by that stimulus. The contingency has been broken.
When You Would Use This in Practice
Assessing Behavior
When conducting a functional assessment or analyzing why a learner behaves a certain way, you’re asking: What MO is in effect? What SD is controlling the response?
A child who elopes during math is responding to an MO (the aversiveness of the task makes escape valuable) and an SD (maybe the door is visible and the teacher is distracted). To interrupt the behavior, you might reduce task difficulty (change the MO) and establish a visual card that signals breaks are available (create an SD for requesting breaks instead).
Choosing Reinforcement Strategies
Identifying current MOs guides your selection of reinforcers. A learner who loves tangible rewards might be unmotivated by praise on a day when they’re overwhelmed. A learner who usually works for social connection might be in an AO state after overstimulation.
By assessing and naming the MO, you pick reinforcers that will actually work today, in this moment.
Designing Prompts and Fading Plans
When you plan how to fade prompts—moving from maximum support to independence—you’re leveraging SDs. You start by prompting heavily while an SD is present. Over time, you reduce the prompt and let the SD (a visual cue, a verbal instruction, a natural contextual cue) take over.
The SD becomes the thing that occasions the response, and the prompt disappears. This only works if the SD has been consistently paired with reinforcement throughout training.
Modifying the Environment
MOs and SDs inform environmental design. A classroom with a visual schedule (SD for expected behaviors), a calm color palette (reducing overstimulation that might create aversive MOs), and clear access to sensory breaks (establishing SDs for appropriate break-seeking) is an MO- and SD-aware classroom.
You’re not relying solely on correction; you’re arranging the space so the right behaviors are naturally cued and motivated.
Examples in ABA
Example 1: Teaching a Mand for Food
The scenario: A 4-year-old with limited language skills is more likely to request when hungry. The caregiver notices he reaches and whines near the kitchen at snack time but doesn’t use words or signs.
How MO and SD work here: Before snack, the child experiences an EO—hunger increases the value of food. The caregiver arranges an SD by placing a cracker visibly on the table and signing “cracker” or showing a picture. The child signs or says “cracker,” and immediately receives the food.
Why this works: The MO (hunger) increases motivation; the SD (visible food + caregiver model) signals that the mand will be reinforced. Over weeks, the caregiver gradually fades the visible food and the model, leaving only the internal MO (hunger at snack time) to evoke the mand. The learner eventually mands without any external cue, demonstrating that the MO—not the prompt—is now driving the response.
Ethical note: The deprivation is minimal and natural (normal meal timing). No basic needs are withheld.
Example 2: Reducing Escape-Maintained Problem Behavior
The scenario: A student displays high rates of task refusal and aggression during math class. The teacher suspects the behavior is escape-maintained: the harder the task, the more likely the student uses problem behavior to get out of it.
How MO and SD work here: The difficulty of the task creates an MO—it makes escape valuable. The teacher redesigns the intervention by lowering task difficulty first, so the reinforcement value of escape drops. Simultaneously, she introduces a green card placed on the student’s desk. The green card becomes an SD: it signals that breaks are available contingent on completing a problem correctly. When the student sees the green card and completes work, they get a break immediately.
Why this works: By changing the MO (reducing task aversiveness), the value of escape decreases, and appropriate task-completion becomes more competitive as a behavior. By introducing a clear SD (the green card), the student learns exactly when and how to get breaks appropriately. Over time, task difficulty can be increased gradually, and the green card can be faded.
Ethical note: The intervention reduces barriers to success rather than increasing punishment or deprivation. The learner’s underlying need for breaks is honored and channeled into appropriate responding.
Examples Outside of ABA
Understanding MOs and SDs helps you see how behavior principles operate beyond clinical settings. These are illustrations of the concepts, not endorsements of the practices.
A retail company sends a limited-time sale email. The email creates an MO: scarcity increases the perceived value of the product. The same email includes a large “Buy Now” button, which serves as an SD—it signals that purchasing is immediately possible. The combination of heightened motivation (MO) and clear opportunity (SD) increases the likelihood of clicking.
A fitness enthusiast struggles with a workout routine. On days when energy is low, the workout feels aversive (an abolishing operation for exercise). But a friend sends a daily reminder text with the class time and location. That reminder is an SD—it signals when and where the group class is available. Sometimes the SD is enough to overcome the low MO, and the person attends. Other days, the low MO wins out.
Both examples show how MOs shift motivation and SDs cue behavior based on learning history and contingency.
Common Mistakes and Misconceptions
Confusing MOs With SDs
The most common error is treating motivation as if it were a cue. A clinician might say, “The child’s tiredness is the discriminative stimulus for aggressive behavior.” But tiredness is an MO—it changes the value of escape or attention, making those outcomes more reinforcing and aggression more likely.
A true SD would be something like, “The child is aggressive when the teacher turns away”—a cue that, by learning history, signals that aggression leads to escape or attention.
Using an SD When the Consequence Isn’t Available
If you place a picture card on a learner’s communication board (intended as an SD) but never honor the request when they point to it, the card isn’t functioning as an SD. It’s a failed prompt.
SDs only work if the contingency is real and consistent. If you say, “Raise your hand,” but ignore raised hands, raising a hand stops being controlled by that stimulus.
Ethically Problematic MO Manipulations
Creating artificial, unnecessary deprivation—withholding food, water, bathroom access, or social contact to increase compliance—is ethically harmful and violates professional standards.
While some natural manipulation of MOs is appropriate (teaching during snack time when hunger creates motivation to mand), artificial deprivation crosses a line. It’s coercive and disrespectful.
Ignoring the Interaction Between MO and SD
Assuming an SD will work regardless of MO is a recipe for intervention failure. A student might be perfectly capable of solving a math problem, and you might have a clear SD (a visual prompt card), but if the value of task completion is low (an AO for work), the student won’t engage.
You must address both.
Conflating Prompts, SDs, and Setting Events
A prompt directly assists the response (physical guidance, a model, a verbal hint). It’s intended to be faded.
An SD signals that a contingency is in place; it’s something you keep because it provides natural information.
A setting event is a broader, longer-lasting context (a loud environment, overall fatigue, poor sleep) that sets the stage for behavior chains.
These are related but distinct. Treating a prompt as an SD leads to learners who depend on that prompt indefinitely instead of developing independence.
Ethical Considerations
Risk of Misuse
The power to modify MOs comes with responsibility. Intentionally creating deprivation—excessive hunger, sleep disruption, or social isolation—to increase compliance is coercive and harmful. Even when technically “legal,” such practices violate the principles of dignity, respect, and least-intrusive intervention.
Similarly, using SDs that mislead learners about reinforcement availability erodes trust and creates confusion that can lead to problem behavior.
Obtaining Informed Consent
Any MO manipulation that affects basic needs—food, sleep, social contact, comfort—must be consented to by the learner (if able) and their guardian/caregiver. They should understand what the manipulation is, why it’s being used, what safeguards are in place, and how long it will last.
Documentation and Monitoring
Your behavior plan should clearly describe:
- The MO you’re manipulating and why that MO was chosen
- The operational definition of the MO (what counts as the state being present)
- The SDs you’re establishing and what contingency they signal
- How you’ll monitor the learner’s welfare if MOs are being manipulated
- The fading plan and exit criteria
This documentation ensures accountability and creates a record for supervision and team review.
Prioritizing Least-Restrictive Approaches
Always ask: Can I use a natural MO instead of an artificial one? Can I increase motivation through preference assessment and selection of high-value reinforcers rather than creating deprivation? Can I establish SDs using naturally occurring cues instead of adding artificial ones?
The goal is to shape behavior in a way that’s respectful, transparent, and minimally invasive. You’re teaching the learner to succeed in a world where MOs and SDs already exist—hunger at meal times, social connection when peers are present, natural cues in the environment. Your intervention should leverage those real conditions, not create artificial ones.
Practice Questions to Strengthen Your Understanding
Scenario 1: A child is more likely to hit a peer when tired. Which best describes the role of tiredness?
A learner who is tired is experiencing an MO—specifically, an abolishing operation that makes positive reinforcers less valuable and makes escape or stimulation-seeking more valuable. Tiredness alters the child’s motivation, making aggressive escape or attention-seeking more likely. It is not an SD (which would signal a contingency) and not a prompt (which would guide response form).
Scenario 2: A teacher places a red card on a student’s desk to indicate that help is available. The student only asks for help when the red card is present. The red card functions as:
The red card is a discriminative stimulus. Its presence signals that the teacher is available and help will be provided if the student asks. The card doesn’t change the student’s internal motivation; it signals a contingency.
Scenario 3: Which practice is least ethical: (A) Using hunger to increase compliance, (B) Pairing praise with task completion, (C) Using visual cues to signal expected behaviors, or (D) Reducing task difficulty to increase success?
Using hunger to increase compliance is least ethical. It manipulates a basic need to force behavior, which is coercive and disrespectful. The other options are standard, less invasive teaching strategies that honor the learner’s dignity.
Scenario 4: A trainer wants a learner to respond to a verbal SD (“Ready?”), but the learner shows low responding because the consequence is weak. Best next step?
Address the MO by selecting a more motivating reinforcer or strengthening the current one. The SD is clear, but without sufficient motivation, the learner won’t respond.
Scenario 5: How would you test whether a stimulus is functioning as an SD rather than a prompt?
Remove direct assistance (the prompt) and observe whether the stimulus still occasions the response. An SD should evoke behavior based on the learning history of the contingency, with no additional help needed. If the stimulus only works when you’re also prompting, it’s not yet an SD.
Related Concepts Worth Exploring
Understanding MOs and SDs deepens when you connect them to related ideas. Functional assessment is the process of identifying the MOs and antecedents that maintain problem behavior. Prompting is how you initially support a learner until the SD can control the response. Reinforcement schedules often use SDs to establish predictable contingencies.
Setting events are broader contextual factors that can create or amplify MOs. Preference assessments help you identify high-value reinforcers before you begin manipulating MOs. And ethical practice ensures all MO and SD work respects client rights and dignity.
Frequently Asked Questions
How do I tell if something is an MO or just a preference?
A preference is something a learner generally likes. An MO is a change in how much they like something right now. A learner might always prefer crackers over carrots—that’s a preference. When you pair that preference with hunger (the MO), crackers become dramatically more valuable in that moment.
To assess: observe whether motivation fluctuates with deprivation and satiation, or whether the learner’s interest stays stable regardless of context. If it changes based on internal state or timing, an MO is likely at work.
Can an SD become an MO or vice versa?
Not exactly—they serve different functions. However, through repeated pairing, an SD can develop conditioned motivating properties. A key might become motivating if it’s always paired with access to a desired space. But the key would still function primarily as a discriminative stimulus while also having acquired some motivating value. The distinction matters for intervention design.
Is it ever okay to use deprivation as an MO?
Only in specific, carefully monitored circumstances and with informed consent. Natural, healthy deprivation (hunger at snack time, fatigue before sleep) is fine. Minimally restrictive, brief manipulations might be justified if safer alternatives don’t work and if the learner’s health and safety are monitored.
But routine, artificial, unnecessary deprivation of basic needs is never ethical. When in doubt, consult supervision and your facility’s ethics committee.
What if an SD is present but the client doesn’t respond?
Assess three things: the MO (is the consequence valuable right now?), prior reinforcement history (has this SD been reliably paired with reinforcement?), and competing contingencies (is there a stronger, incompatible behavior being reinforced?). You might need to strengthen the consequence, adjust timing to catch a relevant MO, or rebuild the SD-reinforcement pairing through repeated trials.
How do I fade SDs to promote generalization?
Plan a gradual removal of discriminative cues while maintaining reinforcement. Teach the behavior across multiple SDs (different teachers, materials, settings). Reduce reliance on artificial cues and let natural cues take over. Use indiscriminable contingencies—sometimes provide reinforcement, sometimes don’t—to make the learner less dependent on obvious cues.
How do I document MO manipulations in a behavior plan?
Include the specific MO being manipulated, the operational definition (when and how long it’s in effect), why it was chosen, what safeguards are in place (monitoring, exit criteria), and the consent obtained. Track data on both the MO state and the target behavior. Schedule regular supervision review points. Make the fading plan explicit so the manipulation doesn’t become permanent.
Key Takeaways
Motivating operations and discriminative stimuli are the two fundamental antecedents shaping behavior. MOs change how much a reinforcer is worth right now; SDs signal when reinforcement is available. Both must be present and properly aligned for efficient behavior change.
Effective interventions address both simultaneously. You assess the MO to choose reinforcers that will actually work. You design and train clear SDs so the learner knows what response leads to reinforcement. You fade prompts over time, letting SDs take over. You monitor and adjust as the learner’s motivations and learning history change.
Ethics and documentation are non-negotiable. Any manipulation of MOs—especially those involving basic needs—must be transparent, consented, monitored, and have a clear exit plan. SDs must truthfully signal reinforcement availability. Your behavior plan must clearly describe the MO and SD strategies you’re using, why they were chosen, and how you’ll know when to fade or discontinue them.
Real generalization comes from understanding natural MOs and SDs in the learner’s everyday environment. Build interventions around the MOs and SDs the learner will encounter in their real life—meal times, peer presence, natural environmental cues, intrinsic motivation. That foundation supports lasting, transferable behavior change.
Start by assessing one behavior problem or skill deficit in your caseload. Ask: What MO is relevant? What SD would clarify when reinforcement is available? How does the learner’s motivation fluctuate across contexts? How can I reduce my prompts and let the natural SD take over? These questions will sharpen your intervention design and deepen your understanding of how MOs and SDs drive real behavior change.
