Instrumental Conditioning II What is learned? Thorndike: S Reinforcement “stamps in” this connection R What is learned? Edwin Guthrie: Contiguity theory, reinforcement doesn’t do much of anything (directly) S R What is learned? S R O ? 2-Process Theory operant S R Pavlovian O 2-Process Theory operant S R Pavlovian CR Evidence for 2-process theory Pavlovian-Instrumental Transfer Phase 1 Phase 2 LeverO LightO # Presses Light No CS Test Light: Lever? No CS: Lever? What is learned? S R ? ? O SO Trapold Phase 1 Phase 2 Test R LeverPellet TonePellet Tone:Left? Right? L LeverSucrose LightSucrose Light:Left? Right? Left Right # Presses Light Noise RO Colwill & Rescorla (1986) Phase 1 Push LeftPellet Devaluation Pellet+LiCl Push RightSucrose Sucrose+LiCl Test Right? Left? What is a reinforcer? Thorndike: A stimulus that produces a “satisfying state of affairs” Operational Definition (behaviorists): That which increases the probability of the response that preceded it. Can we be more precise? The Drive-Reduction hypothesis Servomechanism: device that maintains a controlled variable within a set range Drive Reduction Theory Set Point Amt of H2O in body drives Seek water/ don’t seek water Drive Reduction Considered: Are reinforcers necessary for survival? – Sensory stimulation is a reinforcer • Monkeys work for visual access – Eating to excess – Drugs of Abuse – “Pleasure centers” of the brain Behavioral Regulation View: The Premack Principle • Behaviors are reinforcing, not stimuli • To predict what will be reinforcing, observe the baseline frequency of different behaviors • Highly probable behaviors will reinforce less probable behaviors Premack Revised: The Response Deprivation Hypothesis • Timberlake & Allison (1974) • Low frequency behaviors can reinforce high frequency behaviors • All behaviors have a preferred frequency • Deprivation below that frequency is aversive.