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The Trail Making Test (TMT) is a two-part, timed pencil-and-paper neuropsychological task: Part A measures visual scanning and processing speed, and Part B measures cognitive flexibility and set-shifting by forcing the patient to alternate between numbers and letters. This page covers how each part is administered and scored, how clinicians interpret the results, and where the TMT fits alongside CASRAI’s other bedside cognitive and functional-status tools — the MoCA, Mini-Cog, Glasgow Coma Scale, and NIH Stroke Scale.
What the TMT is, and where it came from
The Trail Making Test traces back to the Army Individual Test Battery (1944), building on earlier attention-testing work by J.C. Partington. Ralph Reitan incorporated it into the Halstead-Reitan Neuropsychological Battery in the 1950s, and his 1958 validation paper (“Validity of the Trail Making Test as an Indicator of Organic Brain Damage”) remains the field’s most commonly cited reference for the test. Unlike the MoCA, the TMT itself is not a certification-gated, publisher-licensed instrument — it is a public-domain paper-and-pencil task reproduced across neuropsychology textbooks and assessment toolkits, though many of the published normative datasets used to interpret a given completion time are separately copyrighted.
Part A vs. Part B: what each measures
| Part | Task | Primary domain measured |
|---|---|---|
| Part A | Connect 25 numbered circles (1–25) in ascending numerical order as quickly as possible, without lifting the pen | Visual scanning, processing speed, visuomotor tracking |
| Part B | Connect 25 circles in an ascending, interleaved number-letter sequence (1-A-2-B-3-C…), up to 13 numbers and 12 letters | Cognitive flexibility / set-shifting, divided attention, working memory, executive function |
Because both parts share the same underlying visuomotor scanning demand, clinicians commonly look at the B-minus-A difference (or the B/A ratio) rather than either time alone: a patient who is simply slow tends to show roughly proportionate slowing on both parts, while a patient with genuine executive dysfunction shows disproportionate slowing specifically on Part B, once the shared scanning component is subtracted out.
Administration and scoring
Each part opens with a short untimed practice trial to confirm the patient understands the task before the timed trial begins. The primary score is time to completion in seconds — lower is better. Under standard administration, if the patient connects the wrong circle, the examiner interrupts immediately, points out the error, and redirects the patient back to the last correct circle rather than stopping the clock, so most errors are captured directly in the completion time rather than scored as a separate point deduction; some research protocols additionally log a distinct error count for analysis. A patient who cannot complete Part B within a reasonable time, or after repeated prompting and redirection, is scored as unable to complete — itself treated as a clinically meaningful poor result, not a missing data point, and should be charted as such rather than left blank.
Interpreting performance
The TMT does not have one universal pass/fail cutoff the way the MoCA has its 26-point line. Completion times are instead compared against normative data stratified by age and education — performance slows meaningfully with age and improves with more years of formal education, so a raw time only means something in that context. Directionally, longer times, more errors, and inability to complete Part B all point toward executive dysfunction, with the disproportionate B-minus-A gap the specific signal clinicians weigh most heavily, more than either raw time in isolation. Like the MoCA and Mini-Cog, the TMT is a screening and characterization tool, not a standalone diagnostic test — an abnormal result is one input into a broader clinical picture, not a dementia or brain-injury diagnosis by itself.
Where the TMT fits in a hospital cognitive-screening pathway
The TMT is used in stroke recovery and rehabilitation assessment (often alongside the NIH Stroke Scale), traumatic brain injury evaluation, Parkinson’s disease and other movement-disorder cognitive monitoring, and pre- and post-operative cognitive baselining alongside tools like the MoCA. It also has a direct structural relationship to the MoCA worth flagging for anyone running both: the MoCA’s Visuospatial/Executive domain embeds a single simplified trail-making-style item (a short number-letter alternation) worth part of its 5 points — a scaled-down proxy for the same set-shifting construct the full two-part TMT measures in much greater depth, not a substitute for administering the full TMT when a more detailed executive-function picture is actually needed. The same processing-speed-versus-set-shifting construct the TMT isolates is considered central enough to neuropsychological assessment generally that it is also incorporated into larger standardized batteries, including the NIH Toolbox Cognition Battery. As with any score that feeds a downstream care or consent decision, chart audits should confirm which part or parts were administered, the raw completion times in seconds (not just a categorical “normal/abnormal” label), and whether the patient was scored as unable to complete Part B — a distinct and clinically important result from merely slow completion.
Frequently asked questions
What is the Trail Making Test used for?
It screens and characterizes processing speed (Part A) and cognitive flexibility / executive function (Part B), commonly in dementia evaluation, stroke and traumatic brain injury assessment, and Parkinson’s disease cognitive monitoring, as one input among several in a broader clinical picture.
What is the difference between TMT Part A and Part B?
Part A is a single ascending sequence of numbers and measures visual scanning and processing speed. Part B alternates between numbers and letters in an interleaved ascending sequence and additionally requires cognitive flexibility and set-shifting, so it is more sensitive to executive dysfunction specifically.
Is a longer time on Part B always abnormal?
Not on its own — Part B is expected to take longer than Part A for everyone, and normal completion times vary substantially by age and education. What clinicians weigh most is a disproportionate B-minus-A gap relative to age- and education-matched norms, not the raw Part B time in isolation.
Do you need certification to administer the TMT?
No. Unlike the MoCA, the TMT itself is not a certification-gated or publisher-licensed instrument — it is a public-domain paper-and-pencil task, though scoring interpretation should still follow a recognized normative dataset stratified by age and education.
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