Tracking behavior, e.g. anti-aircraft gun pointing, typically has a smoother path of motion than would be expected if the operator were a simple error-compensating servo. Following the suggestion that this might be due to continuous anticipation of the target motion, a procedure was devised wherein the tracker continued his lateral "following" motion after the target suddenly disappeared from view. Where rate of motion had been constant this prediction motion preserved the preceding rate with a bias of 1% and an average error of 11%, values consonant with usual tracking accuracy. When the previous motion was accelerated, the continuation was not accelerated but instead appeared based on the averaging of preceding rates.