Reactivity
Reactivity is a change in a person's behavior that happens because they know they are being observed or measured.
When people know they are being watched, they may behave differently from how they usually do. A student may stay on task more when an extra adult sits in the back of the classroom, or a client may show less problem behavior when the supervisor visits. Behavior measured under these conditions may not reflect what happens the rest of the time, so the data can mislead the team.
Reactivity is usually temporary and tends to fade as the person gets used to the observer. Ways to reduce it include observing as unobtrusively as possible, letting the client get used to the observer before data count, using the same observers regularly, and recording during natural routines rather than special sessions. Video recording, with the right consent, can also become part of the normal routine.
Observers can be reactive too: data collectors may score more carefully, or differently, when they know their records will be checked against someone else's. For RBTs, the practical point is to notice and report when a session seemed different because of an observer, such as a new supervisor visiting, and to collect data the same way whether or not anyone is checking.
Example and non-example
| Example | A teen's swearing is recorded much less often on days a new behavior analyst sits in on the session, then returns to its usual level once they have visited several times. |
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| Non-example | An RBT who gradually starts scoring swearing more loosely than the definition is showing observer drift, not reactivity. |
Don't confuse it with
| Observer drift | Reactivity is a change in the observed person's behavior; observer drift is a change in how the observer applies the definition. |
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| Validity | Reactivity is one reason measurement can lose validity; validity is the broader question of whether the data reflect what they are meant to measure. |
Test yourself
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Question 1On the days an unfamiliar visitor sits in the classroom taking notes, an RBT's data show a teen's off-task behavior dropping sharply; it returns to its usual level once the visitor leaves. Which measurement problem does this show?
Show answer
C: Reactivity. Reactivity is a change in behavior caused by the person knowing they are being observed. Data collected under those conditions may not represent the behavior at other times.
- A: Observer drift is a change in how the observer applies a definition; here the student's behavior actually changed.
- B: Treatment drift is a change in how the intervention is implemented, which the scenario does not describe.
- D: Expectation bias means the observer records what they expect to see; here the behavior itself changed in the observer's presence.
Task A.8 · 40-hour curriculum section C
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Question 2An RBT carries out a plan perfectly whenever the supervisor is present but skips steps on other days. What is the main risk for the team?
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D: Fidelity checks will show higher accuracy than the RBT's usual implementation. If implementation improves only when someone is watching, fidelity measured during observations is higher than everyday fidelity. The supervisor may then attribute poor client progress to the plan rather than to the usual implementation.
- A: Observer drift is a recording problem, not a change in implementation under observation.
- B: IOA concerns agreement between observers' records of client behavior, not this problem.
- C: Scores during the supervisor's visits would be higher than usual, not lower.
Task A.8 · 40-hour curriculum section E · RBT Ethics Code 2.02
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Question 3During an ABC observation in a classroom, a student keeps looking at the RBT, and the student's problem behavior is much lower than the teacher reports for other days. What may be happening?
Show answer
C: Reactivity. Reactivity is a change in behavior because the person knows they are being observed. It can make observation data unrepresentative, so it should be reported to the supervisor.
- A: Observer drift is a change in how an observer applies a definition over time.
- B: An extinction burst is a temporary increase in behavior when reinforcement stops.
- D: Spontaneous recovery is the return of an extinguished behavior after time has passed.
Task B.3 · 40-hour curriculum section D · Task A.8
Answer every question to see your score.
On the RBT exam
This term belongs to task A.8 Unreliable data and poor procedural fidelity in content area A, Data Collection and Graphing, which is 13 of the 75 scored questions.