The authors found that the Warner-Warden maze is not a suitable instrument for testing the relationship existing between length and difficulty of material in motor learning, while, if a certain amount of caution is exercised in avoiding patterns which are obviously too easy, the X- and U-types of conventional mazes are suitable for testing this relationship. It would seem that a marked similarity exists between motor learning and verbal learning in the relationship between length of material and relative difficulty of mastery. (PsycINFO Database Record (c) 2006 APA, all rights reserved)