Two scales were constructed to separately evaluate the perceptual and motor difficulty of the finger chords employed to enter letters in a newly designed chord keyboard, developed to provide an efficient alternative to the existing QWERTY keyboard. The index of motor difficulty evaluated the biomechanical problems associated with the execution of the 31 possible chord combinations of five-fingers. The perceptual index scaled the difficulty of identifying the spatial pattern created by each of the 31 chords. A regression equation that was based on the two indexes accounted for about 60% of the variance of actual typing on the chord keyboard. Perceptual and motor determinants appear to be equally potent and mostly independent in their influence on efficient data entry performance.