Intermanual and alternate-form equivalence on the trail making tests

Intermanual discrepancies in performance and alternate-form equivalence on the Trail Making Test were examined among 40 left- and 40 right-hand-preferred normal adults (N = 80). The findings indicate that administration of the Trail Making Tests to the nonpreferred hand does not result in a clinically meaningful difference in score. Neither hand preference nor task complexity (numeric or numeric/lexical) significantly affected the magnitude of the intermanual discrepancy. Mixed-model analyses of variance revealed an interaction (p < .001) indicating that the alternate form for the numeric/lexical Trial Making Test (Trail Making Test, Part D; TMT-D) is slightly more difficult than is the original form Trail Making Test, Part B (TMT-B). Therefore, individuals exposed first to TMT-D performed relatively better in the second trial, whereas individuals exposed first to TMT-B first produced equivalent scores when presented the more difficult form (TMT-D) on the second trial. Thus, although TMT-D is not an equivalent form to TMT-B, it may serve as an excellent alternate form at retest.