The Trail Making Test A and B: a technical note on structural nonequivalence.

The major structural aspect of the Trail Making Test, length of drawn lines needed to complete the tests, was measured and compared for the adult and school-aged child versions. Trail Making B is a markedly longer test than Trail Making A, 32% for adults and 27% for school-aged children. The interpretive assumptions that Trail Making B differs from Trail Making A only in terms of the cognitive skills needed to complete the test and the implicit interpretive bias toward minimizing the motor component of the tests were challenged in this technical note.