SKINNER’S “THEORY” OF INSTRUMENTAL CONDITIONING

• Two-term contingency: R SR

• Nature of reinforcer can vary: R S [SR, Sr, S-R, S-r].

• 3-term contingency (Discriminative operant)

SD : R SR (light: bar press food)

S : R SR (no light: bar press food)

• Chaining of discriminative operants:

• Nature of discriminative stimulus can vary: [exteroceptive, interoceptive, proprioceptive].

SKINNER’S “THEORY” (con’t.)

• Contingency of reinforcement can vary: Rn/t SR

• Schedule of reinforcement can vary: R SR

– subject must emit n responses within a particular time frame t.

• Verbal Behavior. Behavior that is reinforced by a member of one’s verbal community.

• Private events. Discriminative responding to proprioceptive or interoceptive stimuli (stimuli under our skin, Sd : r Sr)

Behaviorist Approach• All learned behavior (human and

animal) can be explained by the principles of classical and instrumental learning theory (2-factor learning theory).

• Classical conditioning:– assumes that CS’s and US’s can be paired arbitrarily.– assumes that temporal contiguity of CS and US is

necessary and sufficient for establishing CR.

• Instrumental conditioning:– assumes that responses selected for reinforcement

are arbitrary.

• No need to postulate mental processes.

EVIDENCE THAT QUESTIONED

BEHAVIORISTS’ ASSUMPTIONS• “Misbehavior” of organisms

• Garcia’s experiment on taste aversion

• Autoshaping and omission training

• Blocking

• Rescorla’s experiment on predictiveness of US.

• Experiments on animal cognition

– Hunter’s definition of representation– Radial maze– Matching-to-sample

GARCIA EXPERIMENT ON TASTE AVERSION

• Rats signalled about two types of noxious stimuli (nausea and shock) by two types of CS (taste and sound).– taste: liquid sweetened with saccharine– nausea: induced by lithium chloride

• Group I: Compound CS [taste & sound] Shock

• Group II: Compound CS [taste & sound] Nausea

• Effect of CS evaluated in 2-bottle choice test:– Bottle 1: saccharine flavored water– Bottle 2: water

• Group I: preferred sweet drink (natural preference)

• Group II: preferred water (avoid natural preference)

Blocking experiment (Kamin)

• Training: CS1 Shock:

CS1 + CS2 Shock

• Test: CS1 fear

CS2 no fear

Predictable and Unpredictable Occurrences

of FoodKey

Light

Food

KeyLight

Food

_______p(Food/Key Light) > p(Food/Key Light)

Predictable:

CS:

US:

_______p(Food/Key Light) =p(Food/Key Light)

Unpredictable:

CS:

US:

Omission Training

SD (Key light):

R (Peck):

SR (Food):

EVIDENCE THAT QUESTIONED

BEHAVIORISTS’ ASSUMPTIONS• “Misbehavior” of organisms

• Garcia’s experiment on taste aversion

• Autoshaping and omission training

• Blocking

• Rescorla’s experiment on predictiveness of US.

• Experiments on animal cognition

– Hunter’s definition of representation– Radial maze– Matching-to-sample

HUNTER ON “REPRESENTATIONS”

...If comparative psychology is to postulate a representative fact, ...it is necessary that the stimulus represented be absent at the moment of the response. If it is not absent, the reaction may be stated in sensory-motor term (Hunter, 1913, p. 21).

MATCHING-TO-SAMPLE

Peck Peck (food) Peck (no food)

Peck Peck (no food) Peck (food)

R R G

R R G

A. Matching-to-Sample

B. Oddity

A. Matching-to-Sample

Peck

RADIAL MAZE