Chapter 6

Law of Effect

• Thorndike’s experiments
• Puzzle box
• Escape latency
• Discrete trial procedure

Law of Effect

• Operant: any behaviour that operates on the environment to produce an effect
• Reinforcer: any event that increases the frequency of a behaviour

Law of Effect

• Any behaviour followed by an appetitive stimulus will increase in frequency

Mechanical Strengthening Process

• Guthrie & Horton (1946)
• Cat in a box with pole
• Stereotypic behaviours

Stop-Action Principle

• Occurrence of reinforcer
• Strengthening of association

• Not immediate
• Dominance of one operant

Problems with Stop-Action Principle

• Muezinger’s (1928) guinea pigs
• Lever press for lettuce
• Not one dominant operant behaviour

Response Classes

• Reinforcement strengthens class of operant responses
• End goal
• Lashley (1942)

Superstitious Behaviour

• Skinner (1948)
• Pigeons
• Grain every 15 seconds
• Development of behaviours
• Accidental strengthening

Superstitions in Humans

• Rituals
• Personal and societal superstitions
• Persistent

Timing?

• Staddon & Simmelhag (1971)
• Interim and terminal behaviours

Shaping, or Successive Approximations

• Conditioned reinforcer
• Previously neutral stimulus that has acquired the capacity to strengthen responses because it has been repeatedly paired with a primary reinforcer

• Primary reinforcer
• Stimulus that naturally strengthens any response that is paired with it

Shaping a Lever Press

• Gradual process
• Reinforce more appropriate/precise responses

Versatility of Shaping Process

• Classical conditioning
• Law of Effect
• Shaping

Skinnerian Research

• B.F. Skinner
• Operant (instrumental) conditioning

• Operant: animal operates on environment
• Instrumental: animal instrumental in obtaining reinforcer

Free Operant

• Operant response can occur at any time
• Operant response can occur repeatedly
• Response rate

Ethologists vs. Skinnerians

• Criticisms
• Not natural environment, artificial behaviours, non-evolutionary constraints
• Defenses
• High experimental control, eliminates confounding variables, general principles seen across species, behaviours, and reinforcers

Successes of Skinnerian Methodology

• Cross-species similarities
• Parallels between lab and real-world
• Applications of lab results to real-world situations

Three-Term Contingency

• Contingency: Y iff X
• 1. Context in which response occurs (discriminative stimulus)
• 2. Response
• 3. Consequence

Discriminative Stimulus

• Consequence occurs if and only if operant response occurs
• Sets the occasion

Other Basic Principles

• Acquisition
• Extinction
• Spontaneous recovery
• Generalization
• Conditioned reinforcement
• Generalized reinforcers

Response Chains

• Reaction chains
• Sequences of behaviours in specific order
• Objective: primary reinforcer
• Conditioned reinforcers
• Discriminative stimuli

Backwards Chaining

• Often used with "complex" training

• Start with last response in chain
• Next, second last response
• Third last, etc.

Forward Chaining

• Start with first response in sequence, then work through to last response in additive steps

Total Task Method

• Only works with humans
• Go through entire sequence
• Verbal feedback at each step in sequence

Biological Constraints on Operant Conditioning

Instinctive Drift

• Breland & Breland (1961)
• Pig, raccoon
• Operant task
• Reinforcer
• Early in training
• Later in training

Autoshaping

• Brown & Jenkins (1968)
• Key pecking with pigeons
• VI-60 grain delivery
• Light on 8 seconds before food delivery
• No response necessary…
• But pigeons started pecking light
• Automaintenance
• Why peck at all?

Is it: Superstitious Behaviour?

• Series of unintentionally shaped responses
• No evidence supporting this
• Rachlin (1969)

• Williams & Williams (1969)

Is it: Classical Conditioning?

• US = grain, UR = pecking
• Transfer UR from grain to key
• Successful when light predictive of food, not otherwise
• Jenkins & Moore (1975)
• Grain or water
• Different beak position
• Stimulus substitution

• Peterson, Ackil, Frommer, & Hearst (1972)
• Rats
• Lever press ---> food or electrical stimulation of brain
• Food: gnaw/lick
• ESB: stroke/groom

Is it: Instinctive Behaviour Patterns?

• Wasserman (1973)
• Chicks, key light, heat lamp
• "Snuggle" key vs. motionless wing spread to lamp
• Physical properties of signal determine response form
• Timberlake & Grant (1975)
• Rat signals delivery of food to second rat
• Social, not food response
• Behaviour-system analysis

General-Principle Approach

• Reinforcement not sole determinant of behaviour
• Phylogenetic and learning influences