Relationships between parts A and B of the Trail Making Test

Two measures of relationship between Parts A and B of the Trail Making Test (TMT) were examined in a large, acute rehabilitation population (N = 497). A difference (B-A) and a ratio (B/A) score were calculated and compared to other neuropsychological measures. The difference score was found to be correlated highly with intelligence and severity of impairment and, to a lesser degree, with age, education, and memory functioning. The ratio measure was correlated moderately or showed no significant relationship with other variables. This finding supported the curvilinear nature of the relationship between the ratio measure and cerebral impairment, as suggested by Golden, Osmon, Moses, and Berg (1981). Both measures were examined for their ability to distinguish between right and left cerebral damage. Only a trend toward differentiating lateralized damage was found; the ratio measure and a geometric transformation of the ratio showed greater sensitivity than did the difference measure. Results are discussed in terms of the potential usefulness of TMT relationship measures in neuropsychological inference.