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When to use

  • Measure how quickly a student responds to prompts or instructions
  • Assess compliance speed, not just compliance success
  • Track task initiation, transitions, or attention responsiveness
  • Separate response accuracy (can they?) from response speed (how fast?)
  • Best for discrete prompts with observable responses and clear timing boundaries

Setup

  1. Choose Latency from the method picker
  2. Define the prompt and response operationally (e.g., “prompt = teacher says ‘open your book’; response = book open to correct page”)
  3. Add an optional definition to align observers on trial structure
  4. Optional: enable activity context to see whether latency varies by setting
Latency recording measures the time elapsed between a prompt, instruction, or cue and the student’s response. Each trial is recorded separately, and Sightline calculates mean latency, median latency, and range. Use it to quantify compliance speed, task initiation, response-to-name, or instruction-following: the clinical questions that a yes/no compliance percentage can’t answer.

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Keyboard shortcuts

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Understanding latency in clinical context

Latency data distinguish between two different concerns:
  1. Can the student perform the behavior? (Accuracy question): answered by whether the behavior occurs eventually
  2. How quickly do they perform it? (Speed question): answered by latency data
A student might comply with every instruction (100% compliance accuracy) but take an average of 2 minutes to start each task while peers start within 10 seconds. Latency data capture this distinction and reveal that the clinical issue is response speed, not response ability. Which direction counts as improvement is target-specific. Shorter latency is the goal for compliance and task-initiation targets, but for latency to the onset of problem behavior, how long a student tolerates a demand before the behavior begins, longer is better. Decide the direction in the operational definition, before you record. Latency is especially useful in:
  • Task initiation: time from direction to begin work until pencil touches paper
  • Compliance: time from instruction to initiation of compliance behavior
  • Transition speed: time from dismissal until student begins the next activity
  • Attention responsiveness: time from “look at me” or name-call until student orients to the speaker
  • Response-to-name: time from hearing name until head turn or eye contact

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Recording trials in Sightline

During recording, each trial appears as a timed episode. Sightline measures the time between when you start the timer and when you stop it. To record a trial:
1

Wait for the prompt to occur

(teacher gives direction, says student’s name, etc.)
2

Press Enter

to start the latency timer
3

Watch the student's response

4

Press the number key

(1, 2, 3…) for the behavior that occurred, which stops the timer and records the trial
5

Mark no response

If the student never responds, press N to mark the trial as no response
If you start a trial by mistake, press Escape to cancel it without recording a trial. Completed trials appear in a list as each one finishes — trial number, latency in seconds, and where in the session it occurred — so you can review recent trials without waiting for the session to end.

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Reading the results

A latency session produces:
  • Mean latency: average time across responded trials (no-response trials are counted separately and excluded from the mean, median, and range)
  • Median latency: the middle value, less skewed by outlier trials than the mean
  • Range: shortest and longest latencies observed
  • Trial count: number of trials, with no-response trials counted alongside
  • Session duration: total observation time
alongside a per-trial chart showing each trial’s latency in order, with a trend read showing whether responses are getting faster or slower across the session. Read the three figures together, because each says something different about the student. The mean is the typical wait. The median tells you whether one very slow trial is inflating that mean. The range is the consistency signal: a tight range means the student responds at a stable speed, so the mean describes them well, while a wide range means latency is erratic and the clinical question shifts from “how slow” to “what makes some trials fast and others slow” (fatigue, task difficulty, time of day).

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Common mistakes to avoid

Clearly define what counts as the start of the response interval. Does task initiation mean pencil touches paper, or pencil touches paper and student begins writing? “Student opens book to page X” is clear; “student begins task” is vague. Pin this down in setup — the clearer your definition, the more consistent your timing.
If you’re inconsistent about when you start the timer (sometimes at the instruction, sometimes after the student has already begun), your data will be noisy. Use a clear, repeatable cue.
If the student has already initiated a response before you start timing (because you weren’t ready), don’t record a trial. Report only the trials you actually measured.
If a teacher pauses before repeating an instruction because a student is processing, don’t count that pause as latency. Latency should measure student response time, not teacher wait time.
A mean based on 3 trials is unstable, and latencies vary day-to-day with time of day, fatigue, and medication. Collect at least 5–8 opportunities per session (8–10+ when possible) and ideally 2–3 sessions before concluding that latency is or isn’t a problem; record at a consistent time, or note when conditions vary.
Don’t use prompts invented for the observation. Use naturally occurring classroom instructions and transitions.
Latency data alone don’t explain why the student is slow. Describe what the student is doing during the latency period (organizing materials, looking around, appearing confused, etc.).

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Latency paired with compliance data

Latency is most meaningful when paired with compliance data:
  • Compliance percentage: what proportion of prompts did the student ultimately follow? (accuracy)
  • Latency: how quickly did they respond? (speed)
A student might show 95% compliance (follows almost all instructions) but with mean latency of 90 seconds, suggesting that the issue is not refusal but slow initiation. Conversely, a student with 85% compliance and mean latency of 8 seconds has two separate issues: some instructions are refused (compliance), and others are responded to slowly (latency).

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Establishing baseline expectations

Latency data are meaningless without a benchmark. Establish one by:
  1. Observing a same-age peer using identical prompt-response definitions: compare target latencies to peer latencies
  2. Consulting classroom norms: ask the teacher “How long should it typically take a student to start work after you say ‘open your book’?”
  3. Using published guidelines: some interventions specify latency expectations (example: 5 seconds for name-response in young children is typical)
Worked example. “Noah’s mean latency to begin work after a direction was 74 seconds across 7 opportunities, compared to a mean of 6 seconds for a comparison peer observed during the same lesson. Noah ultimately began the task on every opportunity; the difference was in how quickly he started, not whether he complied.”

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Example: using latency for intervention planning

A student exhibits the following pattern across 3 baseline sessions: Baseline average: 65 seconds vs. peer 7 seconds (9:1 discrepancy) The intervention implements a visual timer, verbal countdown, and immediate praise for initiating within 15 seconds: Latency is decreasing consistently toward the peer baseline, suggesting the intervention is effective. This feedback guides the teacher’s next decision: continue, intensify, or modify.
For turning these figures into report-ready sentences, see Writing Up Observation Results. For choosing between methods, see Observation Methods.