What does inter-response time (IRT) measure?

• A. Time from start of observation to first response.
• B. Time from antecedent to response.
• C. Time between consecutive occurrences of the behavior.
• D. Duration of each instance.

Answer: (C)

Inter-response time is the interval between two consecutive occurrences of the target behavior. It measures how much time passes from the end of one response to the start of the next, describing how closely the behavior is spaced over time. It’s not the time from the start of observation to the first response (that would be a latency measure), nor the time from an antecedent to a response (also latency), nor the duration of a single response. For example, if the person emits the behavior at times 2 seconds and 7 seconds, the IRT is 5 seconds, reflecting the spacing between those two occurrences. This measure helps us understand patterns of responding, such as whether behavior clusters in bursts or is evenly spaced, and can inform how reinforcement schedules influence timing of responses.