Order effects within the Trail Making and Stroop tests in patients with neurologic disorders

Effects of order of presentation within the Trail Making and Stroop tests were investigated by comparing 50 consecutive patients receiving detailed neuropsychological assessment given the components of each test in standard order with 50 given them in reverse. Groups were well matched on a wide range of demographic and neuropsychological variables. The only significant group difference in mean scores for the test components and derived ratios and differences, a higher Trail Making Test Part B/Part A ratio in the 'reverse' group than in the 'standard' group, was most easily explained in terms of a slight effect of practice in visual scanning. Greater variance in the Stroop Test Part C score and its derivatives in the standard group may have been attributable to factors other than order of presentation. Performance of these tests in patients with neurological disorders is not crucially dependent upon accumulation of proactive interference from simpler to more complex parts; the latter can reasonably be used in isolation.