Clinician tool
CPT score interpretation calculator
Enter raw CPT scores to get population-percentile interpretation across the four most-reported metrics: omission errors, commission errors, mean reaction time, and RT variability.
Methodology
This calculator uses approximate published norms compiled across multiple CPT validation studies (TOVA, Conners CPT-3, QbTest, IVA-2 normative literature). The norms are conservative population estimates; they are not specific to any single test or platform.
Approximate norms used
| Metric | Adult M (SD) | Pediatric M (SD) |
|---|---|---|
| Omission errors | 2.5 (4) | 4 (6) |
| Commission errors | 15 (8) | 18 (10) |
| Mean RT (ms) | 420 (80) | 480 (100) |
| RT variability — SD (ms) | 95 (30) | 110 (35) |
These are approximate. Specific tools have their own age- and sex-stratified norms based on larger samples — use those for clinical decisions.
Why these metrics?
- Omission errors map most directly to vigilance / inattention — the patient's ability to detect target stimuli over time.
- Commission errors map most directly to response inhibition / impulsivity.
- Mean reaction time reflects processing speed and task engagement; elevated values can suggest cautious responding, slowed processing, or sub-effortful engagement.
- RT variability is one of the most ADHD-discriminative CPT metrics in the literature — intra-individual variability is consistently higher in ADHD groups than mean RT alone.
Caveats
- CPT performance is sensitive to engagement, fatigue, time-of-day, sleep, caffeine, and medication state. A single bad performance does not establish a diagnosis.
- CPT is one input among many. Diagnostic decisions integrate clinical interview, developmental history, rating scales, functional impairment, and rule-outs.
- Within-subject change (test–retest with treatment) is often more meaningful than cross-sectional comparison to norms.
- Norms used here are approximations from the published literature, not vendor-proprietary normative scoring.