Schedules of reinforcement — the rules determining which responses are reinforced — are among the most important variables controlling operant behavior. Skinner and Ferster's (1957) systematic study of reinforcement schedules revealed that the pattern of reinforcement, not just its occurrence, produces characteristic and predictable effects on response rate and resistance to extinction.
Continuous vs. Partial Reinforcement
Continuous reinforcement (CRF) reinforces every response and produces rapid acquisition but also rapid extinction when reinforcement ceases. Partial (intermittent) reinforcement reinforces only some responses and produces the partial reinforcement extinction effect (PREE): behavior maintained by partial reinforcement is much more resistant to extinction than behavior maintained by continuous reinforcement, because the organism has difficulty discriminating the shift from partial reinforcement to extinction.
The Four Basic Schedules
Fixed ratio (FR): reinforcement after every nth response. Produces high, steady response rates with a brief post-reinforcement pause. Variable ratio (VR): reinforcement after an average of n responses, varying unpredictably. Produces the highest, most consistent response rates and greatest resistance to extinction — exemplified by gambling behavior. Fixed interval (FI): reinforcement for the first response after a fixed time period. Produces a characteristic "scallop" pattern with a pause after reinforcement followed by accelerating responding. Variable interval (VI): reinforcement for the first response after a variable time period. Produces moderate, steady response rates.
VR: Highest rate, no pause, very resistant to extinction
FI: Scalloped pattern, moderate rate
VI: Steady moderate rate, resistant to extinction
Reinforcement schedules operate throughout daily life. Gambling operates on variable ratio schedules, producing persistent play despite infrequent wins. Checking email or social media resembles a variable interval schedule, producing frequent checking behavior. Piecework pay (FR) produces high work rates with breaks between units. Salary (FI) produces increased effort near review periods. Understanding these natural schedules helps explain patterns of human behavior and can inform the design of incentive systems.