Systems and methods for creating autonomous agents or objects. Agents reactions to physical forces are modeled as springs. A signal representing a force or velocity change for one animation control is processed to produce realistic reaction effects. The signal may be filtered two or more times, each filter typically having a different time lag and/or filter width. The filtered signals are combined, with weightings, to produce an animation control signal. The animation control signal is then applied to the same or a different animation control to influence motion of the object or agent.