Latency
Latency is the time between the onset of a stimulus, such as an instruction, and the start of the response that follows it.
Latency measures how quickly a person begins to respond once a cue is given. The timer starts at the point the definition sets for the stimulus (often the end of an instruction such as "Put on your shoes") and stops when the response begins, not when it is finished. The cue that starts the timer and the start of the response must both be defined clearly so different observers time the same thing.
Latency is useful when the concern is a delay in starting. Examples include a client who takes a long time to begin tasks after an instruction, a student who takes several minutes to sit down after the bell, or a learner whose answers come so slowly that the teaching program needs to address response speed. Sometimes the goal runs the other way: a supervisor may target a longer latency for an impulsive response, such as answering before the teacher finishes the question.
Latency says nothing about how long the response lasts or how many times it happens, so it is often recorded alongside other measures. In discrete-trial teaching, latency also matters indirectly: a long latency before a correct response may be scored differently from a quick one depending on the program's rules, which the supervisor sets.
Example and non-example
| Example | An RBT says "Time to clean up" and starts a timer; the client begins picking up blocks 25 seconds later, so the RBT records a latency of 25 seconds. |
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| Non-example | Timing the gap between the end of one hand raise and the start of the next hand raise is interresponse time, because no instruction or cue starts the timer. |
Don't confuse it with
| Interresponse time | Latency runs from a stimulus to a response; interresponse time runs from one response to the next response. |
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| Duration | Latency ends when the response starts; duration covers the response from start to end. |
Test yourself
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Question 1What is the name for the time between the moment an instruction is given and the moment the client starts to respond?
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A: Latency. Latency is measured from the onset of a stimulus, such as an instruction, to the start of the response. It answers the question "How long did it take the client to begin?"
- B: Duration is how long a response lasts once it has started.
- C: Interresponse time is the time between two responses in a row, not between an instruction and a response.
- D: Rate is the number of responses per unit of time.
Task A.1 · 40-hour curriculum section C
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Question 2A caregiver reports that after being asked to put on their shoes, their child waits a long time before starting. The supervisor asks for data on this concern. Which measure fits it?
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C: Latency. The concern is the delay between the instruction and the start of the response. That delay is latency.
- A: Duration would show how long putting on shoes takes once the child starts, not the delay before starting.
- B: Frequency would count how often the child puts on shoes, not how long they wait to begin.
- D: Interresponse time measures the gap between two responses, not the delay after an instruction.
Task A.1 · 40-hour curriculum section C
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Question 3Over two weeks, a client's latency to begin a task after an instruction drops from about 40 seconds to about 10 seconds. What does this show?
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D: The client is starting tasks sooner after instructions. Latency measures the delay between the instruction and the start of the response. A drop from about 40 to about 10 seconds means the client is beginning tasks more quickly.
- A: How fast a task is finished once started is shown by duration, not latency.
- B: The number of tasks completed is a count, not latency.
- C: Pauses between steps are interresponse times, and longer pauses would not be shown by falling latency.
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.