Apple Logic Pro 9 - Manual (Page 732)

Humanize
Adds a random value to the position, velocity, and length of selected note events. This
preset is useful on rhythmic parts, such as clavinet or piano accompaniments, and drum
and percussion regions (or events). It can add life to strictly quantized material, or notes
that were manually entered (see
MIDI Step Input Recording ).
Alter the values for Position, Velocity, or Length to increase or decrease the random factor
for each of these event parameters.
Reverse Position
Reverses the positions of events (usually notes) within a section.
Change the Position condition values to alter your selection range.
732 Chapter 26 Editing MIDI Events in the Transform Window