is the binary opposite to an intrinsic reinforcer. An extrinsic reinforcer is directly related to the reward which stems from it. For example, in studies conducted by Skinner, a food pellet would be the extrinsic reinforcer for a lever press.
EXTRINSIC REINFORCER: “An extrinsic reinforcer is directly related to the reward which stems from it, they are one of the driving forces behind group participation.”