The default tuning in the Motif XF is called “Equal Temperament“... which divides an octave into 12 equal subdivisions. A musical compromise — all musicians should look this up and understand it (at some point).
When “Pitch Key Follow” = +100% each half step is 1/12 of an octave, such that the low notes are on your left and high notes on your right.
When “Pitch Key Follow” = 0% every key will sound one pitch (pitch does not follow the key pressed)
When “Pitch Key Follow” = -100% each half step is 1/12 of an octave, but the low pitches are to your right, and high pitches are on your left (a reverse piano).
When “Pitch Key Follow” = +200% then each half step is 1/6 of an octave... C-F# is an octave. C-C is two octaves.
When “Pitch Key Follow” = +50% then each half step is 1/24 of an octave...
Useful, as the manual states on things like drum/percussion, and sound effects that do not necessarily require Equal Temperament spacing across the keyboard. There is a “Center Key” parameter as well that determines where the pivot point is...