Behavioural Activation System

A general motivation system that underlies behaviour and affect. Also referred to as Behavioural Approach System. The behavioural activation system regulates appetitive motivation, is sensitive to signals of reward, nonpunishment, and escape from punishment. Activation of this system causes the person to begin (or to increase) movement toward goals.

Reference:
Carver, C. S., & White, T. L. (1994). Behavioral inhibition, behavioral activation, and affective responses to impending reward and punishment: the BIS/BAS scales. Journal of Personality and Social Psychology, 67(2), 319-333. doi: 10.1037/0022-3514.67.2.319.