Interresponse time
Interresponse time (IRT) is the time that passes between two successive responses, measured from the end of one response to the start of the next.
IRT measures the temporal locus of behavior in relation to other instances of the same behavior. The RBT notes when one response ends and starts timing until the next response of the same type begins. A series of IRTs shows how spaced out or bunched together responses are within a session.
IRT is closely linked to rate: as IRTs get shorter, the rate of responding goes up, and as they get longer, the rate goes down. Supervisors use IRT data for behaviors where pacing matters. A client who eats so quickly that they risk choking may have a goal to lengthen the time between bites. A client who asks the same question many times may have a goal to increase the time between repetitions. Differential reinforcement of low rates (DRL) is one procedure that targets longer IRTs.
IRT requires continuous observation and precise timing, so it is usually reserved for specific programs where spacing is the clinical concern. The RBT records it the same way each time, using the end point and start point stated in the definition, and reports unusual patterns to the supervisor.
Example and non-example
| Example | During lunch, an RBT times the gap from the end of one bite (fork leaves the mouth) to the start of the next bite (fork lifts from the plate), recording IRTs of 3, 4 and 2 seconds. |
|---|---|
| Non-example | Timing how long a client takes to start eating after the RBT says "You can eat now" is latency, because the timer starts with an instruction rather than a previous response. |
Don't confuse it with
Test yourself
-
Question 1An RBT starts a stopwatch when a client finishes one sip of water and stops it when the client begins the next sip. What is the RBT measuring?
Show answer
B: Interresponse time. Interresponse time (IRT) is the time from the end of one response to the start of the next response of the same kind. Timing the gap between two sips is IRT.
- A: Latency is timed from a stimulus, such as an instruction, not from the end of the client's previous response.
- C: Duration would time how long each sip lasts, not the gap between sips.
- D: Momentary time sampling checks whether a behavior is happening at set moments; it does not time anything.
Task A.1 · 40-hour curriculum section C
-
Question 2An adult client eats so quickly that they are at risk of choking. The supervisor's plan targets the time between one bite and the next. Which measure will the RBT record?
Show answer
B: Interresponse time. Interresponse time is the time between two responses in a row. Measuring the time between bites lets the team see whether the client is slowing down.
- A: Latency is timed from a stimulus such as an instruction, not from the previous bite.
- C: The length of the whole meal does not show the gap between individual bites.
- D: Partial interval recording only notes whether eating happened in each interval; it does not time the gaps between bites.
Task A.1 · 40-hour curriculum section C
-
Question 3A client's interresponse times on a reading task are getting shorter across sessions of the same length. What does this most likely mean?
Show answer
C: Responses are occurring closer together, so the rate is rising. Interresponse time and rate are closely related: when the time between responses shrinks, more responses fit into the same amount of time, so the rate goes up.
- A: Interresponse time is the gap between responses, not how long each response takes.
- B: The delay after an instruction is latency, not interresponse time.
- D: Shorter gaps between responses within the same session length mean more responses, not fewer.
Task A.1 · 40-hour curriculum section C
Answer every question to see your score.
On the RBT exam
This term belongs to task A.1 Continuous measurement in content area A, Data Collection and Graphing, which is 13 of the 75 scored questions.