NEUTRAL STIMULUS NO REACTION will elicit UNCONDITIONED STIMULUS REFLEX ACTION will elicit a UNCONDITIONED STIMULUS REFLEX ACTION will elicit a NEUTRAL STIMULUS CONDITIONED RESPONSE CONDITIONED STIMULUS will elicit a CONDITIONED STIMULUS Classical Conditioning
Operant Conditioning • Classical: Behavior=reaction • Operant: Behavior=designed to produce consequence • Consequences • positive and negative reinforcement • positive and negative punishment
Consequences • Reinforcement • increases frequency of operant response • positive: arrival of stimulus increases likelihood of operant response; operant response arrival of stimulus • negative: removal of stimulus increases likelihood of operant response; operant response removal of stimulus
Consequences • Punishment • decreases frequency of operant response • positive: arrival of stimulus decreases likelihood of response; response arrival of stimulus • negative: removal of stimulus decreases likelihood of response; response removal of stimulus
Reinforcement Schedules • Continuous: 1 to 1 ratio, a prize every time • Ratio • fixed: 1 to ?, a prize every ? time • variable: ? to ?, maybe a prize, maybe not! • Interval • fixed: announced examination • variable: pop quiz
Classical vs. Operant Conditioning CLASSICAL • Stimulus precedes the response and elicits it • Elicited responses • Learning as a result of association • Pavlov OPERANT • Stimulus follows the response and strengthens it • Emitted responses • Learning as a result of consequences • Skinner
Cognitive View • So far: S-R behaviorists (Watson, Skinner) • Now: S-O-R: stimulus, organism/ interpretation/ response • eg: Herrnstein’s pigeons; concept of trees. Rescorla: class. cond. as S-S association; learned expectancy
Rescorla’s experiment • Question: Do animals learn S-R (or S-S association? • UCS: loud sound; • UCR: freezing; • CS: light
Rescorla’s experiment Loud sound freezing light Loud sound freezing light
Rescorla’s experiment • condition rats • habituate half of them to sound (UCS) • test their reaction to light (CS) • What would S-R vs S-S theory predict?
Pfautz et al. (1978) • Stage 1: 30s tone followed by 10s light • Stage 2: light paired with shock 8 times • Stage 3: tone alone • What does S-R vs S-S predict?
UCS inflation effect • Stage 1: sound (CS), el. shock (UCS); UCR and CR: freezing • Stage 2: 2 levels of shock without sound • Stage 3: sound alone • What does S-R vs S-S predict?
Conditioning depends on CS’ predictive value • CS must precede UCS • CS must signal heightened probability of UCS occurrence • Conditioning ineffective when animal already has good predictor.
Conclusions • classical conditioning “not a stupid process by which organism forms willy-nilly associations between any two stimuli…” • rather: organism as “information seeker”
Cognitive aspects of Operant conditioning Positive/ Negative Contrast effect Overjustification effect
Learning What to Eat • food aversion learning: problem with classical conditioning view