We present a synthesis of ideas and findings from emotion theory, cerebral lateralisation, and control theory which suggest that feedback from behavior motivated by lateralised approach and avoidance systems results in the valence and intensity of emotion. As movement towards appetitive and away from aversive goals deviates from optimal rates, the direction and magnitude of the deviation offers an account of emotional valence. Thus, positive/negative emotion is the first derivative of distance from a goal with respect to time. In addition, the rate of change of movement, the second derivative or acceleration, relates to emotional intensity. We link aspects of this model to well-known psychological variables, and argue that emotion, cognition and behavior are deeply interdependent.