p340fig09.05 An outflow movement command, also called efference copy or corollary discharge, is the souce ot the signals whereby the commanded eye movement position is subtracted from spiral flow to recover expansion flow and, with it, heading.<BR>||  Subtracting efference copy.  Many experiments suggest that the brain internally subtracts the translational component due to eye movements.  Efference copy subtracts the translational component using pathways that branch from outflow movement commands to the eye muscles.