All 5 Terms & Definitions
- Schedules of reinforcement
- The pattern governing when a behaviour is reinforced. Four basic schedules: fixed ratio (FR — reinforce after every nth response, e.g. piece-rate pay), variable ratio (VR — reinforce after an unpredictable number of responses, e.g. slot machines — produces highest and most persistent responding), fixed interval (FI — reinforce first response after a set time, e.g. weekly salary — produces scalloping pattern), variable interval (VI — reinforce after unpredictable time intervals — produces slow, steady responding). Variable ratio schedules produce the greatest resistance to extinction.
- Shaping
- Reinforcing successive approximations to a target behaviour that the organism has not yet performed. By reinforcing behaviours that are closer and closer to the desired behaviour, complex behaviours that could never occur spontaneously can be established — a pigeon pecking a specific target, a child learning to write. Shaping is the operant mechanism behind most skill acquisition.
- Extinction (operant)
- The weakening of an operant behaviour when reinforcement is withheld. If pressing the lever no longer produces food, the rat eventually stops pressing. Extinction is often preceded by an extinction burst — a temporary increase in the rate and intensity of the behaviour before it declines — which explains why parents who eventually give in to a tantrum actually reinforce it more powerfully.
- Discriminative stimulus
- A stimulus that signals when reinforcement is available. In the presence of a green light, lever-pressing produces food; in the presence of a red light, it does not. The green light becomes a discriminative stimulus (SD) that controls the probability of responding. Discriminative stimuli are everywhere: a phone notification signals that checking your phone will be rewarding; opening hours on a shop signal that entering will produce a desired outcome.
- Thorndike's Law of Effect
- Edward Thorndike's foundational principle (1898) that behaviours producing satisfying consequences are strengthened (stamped in) and behaviours producing unsatisfying consequences are weakened (stamped out). Derived from puzzle-box experiments with cats, it established the core logic that Skinner formalised into operant conditioning — that learning is fundamentally about the consequences of behaviour.