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Operant vs. Classical Operant responses understood by comprehending the consequences they produce vs. Pavlovian responses may have environmental effects, but this is not what controls them Edward Thorndike Acquisition of Goal-directed responses. Law of Effect - behavior occurs in a random, trial-and-error fashion. Consequences of a behavior can increase or decrease the future probability of that behavior. 1874-1949 Escape Time Cat Puzzle Box Trials Law of Effect Responses followed by a satisfying outcome will strengthen the association between the situation and the response. Responses followed by a dissatisfying outcome will weaken the association between the situation and the response. Law of Effect Time 1: Press lever Escape from box Strengthens box-lever press association Time 2: Placed in box higher probability of pressing lever Time 1: Pull string Remain in box Weakens box-string pulling association Time 2: Placed in box lower probability of pulling string Discrete-Trial Procedures W. S. Small (1900) – used the maze as a tool to study operant learning in rats. “complex” maze; measures = running speed, latency to reach goal. Hampton Court Palace Maze T-Maze Food No Food Start Straight Alley “Maze” Start Food Operant (Instrumental) Conditioning The Skinner Box: 2 Stages of training: 1. Magazine training 2. Shaping = reinforcement of successive approximations Lever Lever Lever Lever Lever Lever Free-Operant Procedures Discrete-trial procedures provide animal with limited opportunities to respond. Free-operant procedures allow the animal to perform the instrumental response repeatedly without constraint. Discrete-Trial Operant Procedure Lever Light = Discriminative stimulus (SD) Acquisition and Extinction of Lever Press Response Interval Fixed Variable Ratio Schedules of Reinforcement FI scallop Post-reinforcement pause time Size of post-reinforcement pause determined by response-reinforcement ratio PREE What can be an operant? Practically any behavior or behavioral parameter! rate of response time of response variability of response pushes and pulls posture study habits athletic performance arts and crafts creativity bad habits and behavioral disorders Allen et al. (1964) • The case of Ann, a nursery school student • Problems: asocial behavior, complaining, weird habits. • Solution: Stop paying attention to her when she does these things. Extinction of temper tantrums Reinforcement without awareness •Conditioning in amesics – eyeblink in HM “Memento” •Radio static study Subjects told it was an experiment on stress. Twitching of very small thumb muscle actually terminated the aversive stimulus (harsh noise) •Students condition professor Pigeon in a Pelican Ginger Does anyone know how google works? google Marian Breland Bailey – How to train a chicken The famous dancing chicken Limits on Operant Conditioning • Instinctive drift – “misbehavior.” • Belongingness effects – reinforcer/behavior specificity e.g., behavior systems effects. • Unintended consequences –Doing one thing precludes doing other things. • Some responses cannot be conditioned. – E.g., yawning or sneezing. Factors that affect O.C. • The response – Maze running vs. lever pressing – Running vs. throwing football • Temporal contiguity Delayed reinforcement Overcoming the effects of delay • Secondary reinforcers • “Marking” procedure Factors that affect O.C. • The response – Maze running vs. lever pressing – Running vs. throwing football • Temporal contiguity • Contingency “Superstitious Behavior” • Suggested that temporal contiguity more important than contingency • 15-s FT, no response requirement • “adventitious reinforcement” “In 6 out of 8 cases the resulting responses were so clearly defined that two observers could agree perfectly in counting instances. One bird was conditioned to turn counter-clockwise about the cage, making 2 or 3 turns between reinforcements. Another repeatedly thrust its head into one of the upper corners of the cage….” Orienting toward feeder Pecking near feeder Moving along wall ¼ turn Degraded Contingency Effect = bar press = food = light CS Response Perfect contingency Strong Degraded contingency Weak Signal extra food Strong Factors that affect O.C. • The response – Maze running vs. lever pressing – Running vs. throwing football • Temporal contiguity • Contingency • The reinforcer – Magnitude, quality – Upshifts and downshifts Anticipatory Contrast - Crespi (1942) Running Speed (ft/sec) Rats run down maze to find food pellets in goal arm. 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 256-16 Pellets 16-16 Pellets 1 - 16 Pellets 2 4 6 8 10 12 14 16 18 20 2 4 6 8 Trials Reinforcement of Variability