The Trail Making Test, Part B: Cognitive Flexibility or Ability to Maintain Set?

TLDR

The Trail Making Test is a sensitive measure of cognitive impairment, but it is unclear whether Part B taps cognitive flexibility or the ability to maintain a complex response set beyond what Part A requires. The study aimed to determine which of these two abilities primarily drives performance on TMT Part B. One hundred twenty‑one Veterans Affairs patients completed the TMT and a battery of executive‑function tests, and regression analyses examined which measures predicted Part B performance after controlling for Part A. Results preliminarily indicate that Part B is more sensitive to cognitive flexibility—as reflected by Wisconsin Card Sorting Test perseverative errors—than to set‑maintenance ability.

Abstract

The Trail Making Test (TMT) is a well-established test sensitive to impairment in multiple cognitive domains. There has been ambiguity about which cognitive demands are placed on the patient by TMT Part B over and above those required to perform TMT Part A. In particular, cognitive flexibility and ability to maintain a complex response set have been 2 competing hypotheses. This study preliminarily examined which of these 2 abilities primarily contributes to Part B performance. A total of 121 clinically referred Veterans Affairs patients were administered the TMT, as well as other tests of executive and other cognitive functions. Regression analyses were used to examine which tests predicted Part B performance above and beyond Part A performance. The results provide preliminary support for TMT Part B performance being more sensitive to cognitive flexibility (operationalized as Wisconsin Card Sorting Test [WCST], percent perseverative errors) than ability to maintain set (operationalized as WCST, failure to maintain set).