Motivating Operations (MOs) change how much we want something, while Discriminative Stimuli (SDs) signal when a behavior will be rewarded. MOs affect motivation; SDs provide cues for action.
What Are Motivating Operations?
Motivating Operations work behind the scenes in our daily lives. They change how much we value certain things or activities.
Think about food when you’re hungry versus when you’re full. When you haven’t eaten for hours, food becomes very valuable. You might walk across campus just for a snack. But right after a big meal, that same snack holds little appeal.
This is a Motivating Operation in action. Your hunger level changes how much you want food. It doesn’t tell you where to find food or when to eat. It just makes food more or less important to you.
MOs have two main jobs. First, they change how reinforcing something is. Second, they make behaviors more or less likely to happen.
Understanding Discriminative Stimuli
Discriminative Stimuli work differently. They act like green lights for behavior. They tell us when a specific action will likely pay off.
Picture a vending machine. The lit-up display shows which snacks are available. This display is a Discriminative Stimulus. It signals that putting money in the machine will get you a snack.
But if the machine is unplugged and dark, you probably won’t try to buy anything. The dark display signals that your money won’t work right now.
SDs don’t make you want something more or less. They just tell you when your behavior will work.
Key Differences Between MOs and SDs
The main difference lies in what each one does to behavior.
MOs change the value of consequences. They make rewards more or less appealing. When you’re thirsty, water becomes more valuable. When you’re not thirsty, water matters less.
SDs signal when behavior will be rewarded. They don’t change how much you want the reward. They just tell you when you can get it.
Here’s another way to think about it. MOs answer the question “How much do I want this?” SDs answer “When can I get this?”
Real-World Examples in Action
Let’s look at some everyday situations to see both concepts working together.
Example 1: The Coffee Shop
You walk past your favorite coffee shop every morning. Some days you buy coffee, others you don’t. What makes the difference?
If you slept poorly last night, you really need caffeine. Your tiredness is a Motivating Operation. It makes coffee more valuable to you.
The “Open” sign in the window is a Discriminative Stimulus. It tells you that going inside and ordering will get you coffee.
Both work together. Your tiredness motivates you to want coffee. The open sign tells you when you can get it.
Example 2: Playground Behavior
A child sees other kids playing on swings. Sometimes she joins them, sometimes she doesn’t.
If she’s been sitting in class all morning, physical activity becomes more appealing. Being sedentary for hours is a Motivating Operation. It increases the value of moving around.
Seeing other children having fun on the swings is a Discriminative Stimulus. It signals that going to the playground will likely result in fun and social interaction.
How RBTs Use This Knowledge
Registered Behavior Technicians use both concepts to help clients learn new skills.
When working on communication goals, an RBT might create Motivating Operations. They might put a favorite toy just out of reach. This makes asking for help more valuable to the child.
The RBT also provides clear Discriminative Stimuli. They might hold up a picture card that means “help me.” This signals when asking for help will get results.
Good RBTs know that timing matters. They create situations where the child really wants something (MO) and then provide clear signals about how to get it (SD).
Common Mistakes to Avoid
Many people confuse these two concepts. Here are the most common mix-ups.
Mistake 1: Thinking SDs Create Motivation
SDs don’t make you want things more. They just tell you when behavior will work. A store sign doesn’t make you hungry. It just tells you where to buy food.
Mistake 2: Ignoring MOs in Programming
Some programs focus only on teaching when to do behaviors (SDs). They forget to consider whether the person actually wants the outcome (MOs).
This leads to robotic responses. The person might know when to ask for something but doesn’t really care about getting it.
Mistake 3: Using Only Artificial MOs
Real motivation works better than fake motivation. Making someone thirsty just to practice asking for water isn’t always the best approach.
Natural MOs work better. If someone is naturally thirsty, that’s a perfect time to practice communication skills.
Practical Applications for Families
Parents can use these concepts at home too.
Create natural Motivating Operations by paying attention to what your child already wants. If they love music, use that motivation to work on other skills.
Provide clear Discriminative Stimuli by being consistent. If you always respond to polite requests but ignore demanding behavior, you create clear signals about what works.
Don’t force motivation when it’s not there. If your child isn’t interested in something right now, wait for a better moment or find something they do care about.
Why Both Matter in ABA
Effective ABA programs use both concepts together. You need motivation for learning to happen. You also need clear signals about when behavior will be successful.
MOs ensure that consequences matter to the person. SDs ensure that the person knows when to use their skills.
Programs that ignore either concept tend to fail. Without proper MOs, people go through the motions without caring. Without clear SDs, people don’t know when to use what they’ve learned.
The best interventions create natural motivation and provide clear, consistent cues. This combination leads to meaningful behavior change that lasts beyond the therapy session.
Understanding these differences helps everyone involved in ABA create better programs and achieve better outcomes.