The expanded Trail Making Test: rationale, development, and psychometric properties

Many procedures have been employed to determine the specific cognitive components necessary for successful Trail Making Test (TMT) performance. Yet, there is still considerable disagreement in the literature as to what these components might be. The present study explores an alternative methodology to address this problem. By systematically varying the stimuli within the TMT format, it may eventually be possible to isolate the cognitive demands of this test. As the first step toward this goal, two experimental forms of the TMT, forms X and Y, were developed and subjected to empirical validation. The results indicate that this Expanded Trail Making Test possesses adequate concurrent and criterion validity to support the proposed methodology. The results also suggest that the psychometric properties of the TMT format are robust to alterations in test stimuli. Secondary benefits of this methodology, in terms of explaining between-group variance and in terms of cross-cultural assessment, are discussed.