NEGATIVE FEEDBACK control systems are inhibitory. They oppose or “negate” a change (such as a drop in temperature) by creating a response (production of heat) that is opposite in direction to the initial disturbance (fall in temperature below a normal set point). POSITIVE FEEDBACK control systems are stimulatory. Instead of opposing a change in the internal environment and causing a return to normal, positive feedback tends to amplify or reinforce the change that is occurring.