TEST

Trail Making Test (TMT)

Processing speed, visual attention, and cognitive flexibility

One of the most widely used neuropsychological tests for assessing executive functions. Its two-part design (A and B) makes it possible to separate basic visuomotor speed from the added cost of attentional switching, accurately identifying where the cognitive difficulty originates.

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2

PARTS (A AND B)

25

NUMBERS IN PART A

13

ALTERNATING ITEMS IN B

ms

PRECISION

WHAT THE TEST IS

Processing speed and executive control, separated into two parts

The Trail Making Test, originating from the Army Individual Test Battery (1944) and incorporated by Halstead and Reitan into clinical batteries, is one of the most widely used and best-validated neuropsychological tests for assessing attention and executive functions (Linari et al., 2022).

Part A is a relatively pure index of visuomotor speed, visual search, and sustained attention. Part B adds switching between two mental series (numbers and letters), which places greater demands on cognitive flexibility, working memory, and inhibitory control (Sánchez-Cubillo et al., 2009). The A–B comparison makes it possible to distinguish general slowing from a specific executive deficit, typically associated with the dorsolateral prefrontal cortex.

HOW IT IS ADMINISTERED

Connect 25 numbers and then alternate numbers and letters

In Part A, the patient connects 25 numbered circles from 1 to 25 in ascending order as quickly as possible. In Part B, they alternate between numbers and letters following the sequence 1-A-2-B-3-C… up to 13. Each part is preceded by a short practice block with the first 8 elements.

The response is made using a mouse or touchscreen. If the tap is correct, the circle is highlighted and a line is drawn to the previous one; if it is incorrect, the outline flashes red and the error is recorded with no additional penalty. The platform records times, the exact sequence of taps, and latencies per stimulus.

WHAT THE TEST MEASURES

Indicators and their interpretation

Each indicator is interpreted against normative data stratified by age, sex, education, language, and device, and is integrated with the qualitative pattern of the sequence.

Total time Part A

Seconds required to complete the 1→25 sequence. A relatively pure index of visuomotor speed, visual search, and sustained attention.

High time: general cognitive slowing, visuoperceptual, or motor problems.
Low time: preserved psychomotor speed and visual scanning.

Total time Part B

Time on the alternating task. Reflects cognitive flexibility, working memory, and inhibitory control on the basis of processing speed.

High time: difficulty in mental set-shifting, characteristic of frontal lesions, Parkinson’s disease, or ADHD.
Low time: efficient alternation.

Errors

Taps that do not follow the correct sequence, recorded separately in A and B. Measures accuracy, monitoring, and rule control.

Many errors: impulsivity, disorganization, monitoring failures.
Low errors: preserved attentional and executive control.

B/A index

Ratio between time B and time A. Normalizes the executive cost relative to the individual’s baseline speed.

Ratio > 3: specific inefficiency in alternation (TBI, schizophrenia).
Ratio close to 1: preserved cognitive flexibility.

B – A difference

Extra seconds required for alternation compared with the simple task. Considered the best indicator of “pure” executive control (Sánchez-Cubillo et al., 2009).

High difference: significant executive overhead.
Low difference: good cognitive control.

Maximum latencies and quadrants

Five longest intervals between taps in each part, with their location by screen quadrant. Enables qualitative analysis that is only possible in a digital version.

Spatial bias: suggests hemispatial neglect.
Delays at the end: attentional fatigue.

REFERENCES

Bibliography

Linari, I., Juantorena, G. E., Ibáñez, A., Petroni, A., & Kamienkowski, J. E. (2022). Unveiling Trail Making Test: Visual and manual trajectories indexing multiple executive processes. Scientific Reports, 12, 14265.
Sánchez-Cubillo, I., Periáñez, J. A., Adrover-Roig, D., et al. (2009). Construct validity of the Trail Making Test. Journal of the International Neuropsychological Society, 15(3), 438–450.
Salthouse, T. A. (2011). What cognitive abilities are involved in trail making? Intelligence, 39(4), 222–232.
Tombaugh, T. N. (2004). Trail Making Test A and B: Normative data stratified by age and education. Archives of Clinical Neuropsychology, 19(2), 203–214.
Peña-Casanova, J., et al. (2009). NEURONORMA Project: Norms for verbal span, visuospatial span, letter and number sequencing, Trail Making Test, and SDMT. Archives of Clinical Neuropsychology, 24(4), 321–341.
Periáñez, J. A., Ríos-Lago, M., Rodríguez-Sánchez, J. M., et al. (2007). Trail Making Test in traumatic brain injury, schizophrenia, and normal ageing. Archives of Clinical Neuropsychology, 22(4), 433–447.