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.
Key Structures
- Basal ganglia — A group of subcortical nuclei involved in action selection, procedural learning, habit formation, and reward-based decision making.
- Ventral tegmental area — A midbrain dopamine nucleus that projects to limbic and cortical regions, central to reward prediction and motivation.
- Prefrontal cortex — The anterior portion of the frontal lobe, critical for executive functions including planning, decision-making, working memory, and cognitive control.
- Nucleus accumbens — A ventral striatal structure central to reward processing, motivation, and reinforcement learning.
- Extinction — The process by which a conditioned response weakens when the reinforcing stimulus is no longer presented, revealing that extinction is new learning, not erasure.
Key Functions
Determine patterns of reinforcement delivery (fixed/variable ratio or interval) that shape response rates 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.
Disorders
- Gambling disorder (variable ratio schedules) — A behavioral addiction characterized by persistent maladaptive gambling despite negative consequences, involving dysregulated reward processing, particularly in relation to variable ratio schedules.
- Addiction — A chronic condition characterized by compulsive substance use or behavior despite harmful consequences, involving dysregulated reward circuitry.
- Compulsive behaviors — Repetitive actions performed in response to obsessions or rigid rules, aimed at reducing anxiety or preventing feared outcomes.
- Extinction — Failure to detect a contralesional stimulus only when a competing ipsilesional stimulus is presented simultaneously; single stimuli detected normally.