A.5 Operational Definitions

By RBThub February 23, 2026

Imagine you tell a babysitter, "Call me if he gets angry."
The child gets frustrated and throws a toy. The babysitter thinks, "He's not angry, just frustrated," so she doesn't call.
Later, the child screams. She thinks, "He's tired, not angry." She doesn't call.
The problem isn't the child; the problem is the word "Angry." It is subjective. In ABA, we cannot fix what we cannot clearly define. We must use Operational Definitions.

Executive Summary

This video explains the cornerstone of ABA: Operational Definitions. It distinguishes between "Observable" behavior (what you can see/hear) and "Nonobservable" behavior (feelings/thoughts). You will learn why vague words like "angry," "lazy," or "bad attitude" are dangerous in therapy, and how to replace them with concrete, measurable descriptions like "yelling," "sleeping," or "crossing arms."

⏱️ Video Timeline

00:00
Observable vs. Nonobservable
If two people can see it and agree on it, it's observable. If you have to guess what they are feeling, it's nonobservable.
02:25
Why Objectivity Matters
Tracking "sadness" is impossible because we can't measure it. Tracking "crying duration" is precise and reliable.
06:30
Defining Behaviors Clearly
Replacing vague labels (e.g., "non-compliant") with specific actions (e.g., "looking away," "saying no").
14:30
Onset & Offset
Knowing exactly when a behavior starts (onset) and stops (offset) is critical for accurate timing.

🔑 Key Insights

The "Dead Man's Test": If a dead man can do it (e.g., "stay quiet," "not move"), it is NOT behavior.
Observable: Can I see it? Can I hear it? Can I count it?
Measurable: Can I put a number on it? (Frequency, Duration, etc.)
Subjective Labels: "Rude," "Lazy," "Happy." Avoid these. Use "Action Verbs" instead.

❓ Frequently Asked Questions

Q: Why can't we say a client is "sad"?
A: Because "sad" looks different for everyone. One person cries, another sleeps, another eats. We track the action (crying), not the feeling.
Q: How do I define "Non-Compliance"?
A: Be specific! Define it as: "Turning head away," "Saying 'No'," or "Falling to the floor" within 5 seconds of a demand.

1. The Stranger Test

The Rule: An Operational Definition is good only if a complete stranger could read your definition and pick out the behavior immediately without ever meeting the client.
The "Human" Translation: If I tell you to look for "aggressiveness," you might look for hitting, but I might mean yelling. We will be confused.
If I tell you to look for "Hitting with an open hand," we will both count the exact same thing. That is a good definition.
Clinical Example

Bad Definition: "Johnny is being bad." (Too vague).
Good Definition: "Johnny is throwing items larger than 5 inches across the room." (Clear, measurable).

2. Objective vs. Subjective

✅ Objective (Fact)
- "Client yelled 'No'."
- "Client hit table 3 times."
- "Client sat for 5 minutes."
❌ Subjective (Opinion)
- "Client was rude."
- "Client felt angry."
- "Client didn't want to work."

3. Onset & Offset

To measure duration accurately, you must know the exact boundaries of the behavior.
Onset: When does the clock start? (e.g., "At the first audible scream.")
Offset: When does the clock stop? (e.g., "After 30 seconds of silence.")

📝 Knowledge Check

Can you spot the bad definition?

Q1: Which of these is a proper Operational Definition?

Answer: "Striking the table with an open palm."
This describes the action observable by anyone. "Being angry" or "Having a tantrum" are too vague.

Q2: You write in your notes: "Client was happy today." Is this acceptable?

Answer: NO.
"Happy" is subjective. You should write: "Client smiled, laughed 5 times, and engaged in play without refusal."
▶

Measurement Quiz

Mock Exam

Test your ability to distinguish between objective and subjective definitions.

Start Practice Test

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