Motor dexterity is a composite measure of 2 motor tests: Purdue pegboard test and finger-tapping test.

Motor dexterity is measured bilaterally using the Purdue pegboard and an electronic tapper (Western Psychological Services, Los Angeles, California). Participants are asked to perform each test twice with each hand. The average of these 4 trials for the Purdue pegboard test represents a performance score, in number of pegs correctly inserted into the pegboard. The average of the 4 trials for the finger-tapping test represents a performance score, in number of finger taps.

The performance scores are then converted to a z-score, using the baseline mean and standard deviation of all study participants. The z-scores for the Purdue pegboard test and the finger-tapping test are then averaged to yield a composite measure of motor dexterity.