Ivan Petrovich Pavlov (1849-1936) Chapter 7 1 Ivan Petrovich Pavlov 1. Born in Ryazan, Russia on Sep 14, 1849. 2. Studied the digestive system and won the Nobel Prize in 1904 for physiology and medicine. 3. At age 50 discovered classical conditioning. Nobel Prize Seal (1849-1936) 2 http://www.epub.org.br Salivary Reflex Weak Acid Tongue Receptors Glossopharyngeal Nerve (sensory) Medulla Glossopharyngeal Nerve (motor) Dilates blood vessels in parotid gland Salivation in mouth Parotid duct releases watery saliva 3 1
Experimental Setup www.sruweb.com 4 Classical Conditioning Step 1: Reflex Weak Acid Unconditioned Stimulus () Salivation Unconditioned Response (UR) 5 Classical Conditioning Step 2: Selection Bell Neutral Stimulus or Conditioned Stimulus () 6 2
Classical Conditioning Step 3: Training Bell Weak Acid Salivation UR 7 Classical Conditioning Step 4: Acquisition Bell Salivation http://www.youtube.com/watch?v=cpolxen54ho 8 Features of Classical Conditioning 1. Pavlov suggested that an association builds between - after conditioning takes place (psychic reflex). 2. (saliva) is similar to UR (saliva), however magnitude (quantity of saliva) for is lesser than UR. 3. For optimal conditioning to take place needed to occur ½ second before. 9 3
(Saliva, ml) History of Classical Conditioning 1. The concept of conditioning was suggested in 1751 by Robert Whytt, but no one was interested in the idea. 2. In 1902, E. B. Twitmyer reported knee-jerk reflex based on a similar association between bell and knee-jerk response. 10 Extinction (Bell) (Weak Acid) 1. (salivation) extinguishes if (weak acid) is removed. 2. Thus (weak acid) serves as reinforcement. 11 Extinction 18 16 14 12 10 8 6 4 2 0-2 Removed 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Trial Extingushed 12 4
(Saliva, ml) Spontaneous Recovery 1. After extinction of (salivation) a rest period spontaneously recovers the. 2. during spontaneous recovery, has a lower magnitude than UR and extinguishes rapidly if not reinforced with a. 13 Spontaneous Recovery 18 16 14 12 10 8 6 4 2 0-2 Extingushed 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Trial Rest Spontaneous Recovery 14 Higher-order Conditioning (weak acid) (Bell) 2 (Buzzer) 3 (Tone) UR First-order conditioning Second-order conditioning Third-order conditioning 15 5
Higher-order Conditioning During conditioning a can develop reinforcing properties (secondary reinforcer), and can be used in place of a (primary reinforcer) to condition a second. This second can then be used to condition a third, and so on. Second and thirdorder conditioning are called higher-order conditioning. 16 Higher-order Conditioning 1. Magnitude of (salivation) decreases with each successive ordered conditioning. 2. Extinction is faster for higher-ordered conditioned responses. 3. Higher-order conditioning is a complex form of learning. 17 Generalization (weak acid) (2kHz Tone) (1kHz Tone) (3kHz Tone) UR Generalization refers to increased capability of producing a by stimuli that are similar to the first that lead to conditioning. 18 6
(Saliva, ml) Generalization Gradient 16 12 8 4 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Tone Intensity (khz) 19 Fear Generalized After conditioned fear of the white furry rat was inculcated in Little Albert, he was afraid of other stimuli that resembled the white rat, like a furry rabbit, a dog, or a Santa Claus mask, etc., (Watson & Rayner, 1920). www.bdrum.com www.greenhead.ac.uk 20 Generalization 1. Magnitude of (salivation) is lower to s other than the first (2kHz tone). 2. Responses extinguish faster to s other than the first (2kHz tone). 21 7
Discrimination (2kHz Tone) (weak acid) (1kHz Tone) No weak acid (No Salivation) You can train animals to discriminate between two s, such that to one is different from the other. 22 Discrimination Training 1. Repetition: Many - pairing that lead to a specific. 2. Selection: Among many only one reinforced with to generate a. 3. Discrimination precedes generalization. With successive training the two s lead to different (discriminate) s. 23 Tone Shock - Relationship Forward Conditioning Delayed Conditioning Strong conditioning Simultaneous Conditioning Backward Conditioning Weak/No conditioning 24 8
Physiological Basis of Conditioning 25 Physiology of Conditioning (Tone) (Acid) Brain Auditory Area Weaker brain activity Temporary Connection (excitation) Medulla Dominant brain activity Neighboring CNS areas UR/ 26 Extinction (Tone) Brain Auditory Area Weaker brain activity Neighboring CNS areas Acid Temporary Connection (inhibition) Medulla Dominant brain activity (No Salivation) 27 9
Generalization (Irradiation) (2kHz (1kHz (3kHz Tone) Brain Auditory Area Weaker brain activity Neighboring CNS areas (Acid) Medulla Dominant brain activity 28 Irradiation Pavlov described irradiation as the physiological process that took place during generalization. The conditioned brain area irradiated (spilled) over other brain areas permitting similar s to elicit. 29 Discrimination: Concentration (1kHz (2kHz Tone) Brain Auditory Area Weaker brain activity Neighboring CNS areas (Acid) Medulla Dominant brain activity (No 30 10
Interspersed Trials Concentration Two s (or more) can be associated with two kinds of s. s discriminate across s because they excite non-overlapping areas (concentration) in the brain. Thus one results in one kind of (salivation) and the other in another kind of (no salivation). 31 Excitatory Conditioning (Bell) (Weak Acid) UR (Bell) Excitatory conditioning occurs when a (bell) gets associated with occurrence of (weak acid). Thus excites a. 32 Inhibitory Conditioning Phase I: Acquisition (Tone) s (Tone + Light) (Air Puff) (No Air Puff) (Eye Blink) (No Eye Blink) Phase II: Testing (Light) (No Eye Blink) Inhibitory conditioning occurs when a (light) gets associated with absence of (no air puff), and does not elicit a (eye blink). 33 11
Excitation & Inhibition Excitation and inhibition govern all central nervous system (CNS) activities caused by environmental events. Pavlov often talked about Janus, the Roman god with two faces in opposite directions. These opposing faces related to excitation and inhibition, as two opposing processes in the nervous activity (Babkin, 1949). 34 Cortical Mosaic This excitatory and inhibitory activity in the brain forms a cortical mosaic. Momentary cortical mosaic determines how an organism will respond to its environment at a given moment, and Dynamic Stereotype is a stable cortical mosaic. Environment Brain I E Brain I E 35 Compound Conditioning When two s of equal strength are used together to conditioned a response, the is strong. When these s are then tested separately they both produce moderate responses. 36 12
Strong Response Weak Response Compound Conditioning Phase I: Acquisition s Light (medium) + Tone (medium) s Light (medium) + Tone (medium) Phase II: Testing Light (medium) Tone (medium) (Weak Acid) Strong Response Moderate Responses 37 Overshadowing In overshadowing one is more salient (high tone) than the other (low light). Thus tone elicits a stronger than light (Pavlov, 1927). 38 Phase I: Acquisition s Light (medium) + Tone (high) s Light (medium) + Tone (high) Phase II: Testing Light (medium) Overshadowing (Weak Acid) Strong Response Tone (medium) 39 13
Strong Response Weak Response Blocking Blocking involves conditioning a tone () to elicit a (Fear; Kamin, 1969) through shock (). When the tone reliably elicits the ; tone is paired with another (light) as a compound stimulus to elicit. When the light and the tone are then tested separately it is the tone that elicits a stronger (fear) and not light. So the tone blocks the light. 40 Phase I: Prior Conditioning Tone (medium) Phase II: Acquisition s Tone (medium) + Light (medium) Phase III: Testing Light (Medium) Tone (Medium) Blocking (Shock) (Shock) Strong Response Strong Response 41 Overexpectation When two s have been paired separately with the and then together, both protocols produce strong association. When the two s are tested later separately produce a moderate response. This is called overexpectation. 42 14
Strong Response Strong Responses Overexpectation Phase I: Prior Conditioning Tone (medium) Light (medium) (Shock) (Shock) Phase II: Compound Stimuli s Tone (medium) + Light (medium) Phase III: Testing Light (Medium) Tone (Medium) Moderate Responses 43 Signal Systems Pavlov s work introduced stimulation in the context of future behavior. And therefore suggested that preceded as a signal to biologically significant events. (Bell) (Weak Acid) UR Signal 44 Types of Signals Events that evoke biological responses are termed as first signal system. Symbols that represent these events and lead to biological responses are called second signal system or signals of signals. Signal System Stimulus Response First signals See a lion You sweat Second signals Hear the word lion You sweat 45 15
www.flyfishingdevon.co.uk Other Ideas about Classical Conditioning 46 Contingency Kamin s (1969) blocking effect and surprisingness hypothesis lead Rescorla & Wagner (1966, 1972) to propose that classical conditioning relied on contingency between and. 47 Rescorla-Wagner Model 1. Dogs jump the hurdle in the shuttle box to avoid the shock which comes after 30 seconds. Dogs jump based on their own mental clocks. 48 16
Rate of Responding www.flyfishingdevon.co.uk Contingency 2. Dogs were taken out of shuttle box and were put into three contingency groups (- pairing). Contingency Positive Negative No - (tone comes before shock) - (tone comes after shock) / (tone-shock follow each other randomly) 49 Training 3. Dogs were put back in the shuttle box and trained to avoid the shock with tone as the. 50 Results Contingency Positive Negative No Rate of responding increased Rate of responding decreased Rate of responding same as baseline Tone Precedes Shock Tone Follows Shock Tone/Shock Random 51 17
Contingency Rescorla & Wagner (1966, 1972) thus suggested that a contingency exists between and to cause conditioning and not to - contiguity as proposed by Pavlov (1927). Tone (T) Shock (S) T T T T T T S S S S S S Little or no conditioning Tone (T) Shock (S) T T T S S S Strong conditioning 52 Learned Helplessness Seligman et al., (1969, 1975) argued that the animals do learn a state of helplessness in Rescorla s, No Contingency group. The group loses its relevance (learned irrelevance) to. Whenever a is paired with this, its efficacy is diminished. 53 Superconditioning 1. Concept of - relevance became important in aversive conditioning. Naturally it was food that got associated with illness and not the plate in which it was served. Certain belong with. 2. Conditioning is possible with longer time interval between and the. (Garcia, 1960s). John Garcia (1917-Present) 54 18
Taste Aversion Rats like drinking saccharine water. Garcia & Koelling (1966) used light, tone and taste (saccharine water) as compound. They called it the bright-noisy-tasty water. 55 Phase I: Acquisition Group 1 Group 2 Phase II: Testing Group 1 Group 2 Aversive Conditioning s Light + Tone + Taste s Light + Tone + Taste s Light or Tone s Light or Tone (Shock) (Drug) (Fear light and tone but drink saccharine water) (Fear light and tone and NOT drink saccharine water) 56 Taste Aversion: Garcia Effect 1. Some s are biologically relevant (or belong to). 2. Time delay between and the can be very long (up to hours) unlike observed in other forms of classical conditioning. 3. Only a few presentation (sometime one) are enough to bond with. 4. Taste aversions are resistant to extinction. 57 19
Clinical Applications 1. Extinction: Unwanted habits can be eliminated through the process of extinction. If is withdrawn the will extinguish after some time. When mother ignores the toddler s tantrum, whining behaviors fades. 2. Counter-conditioning: is paired with a noxious to counter the original - strength. Smoking (pleasure) replaced with anectine (threat) to quit smoking. 58 Clinical Applications 3. Flooding: Sustained presence of the abolishes an undesired response like a phobia. The individual is forced to stay with the fear inducing stimulus only to learn that it is not threatening. 4. Systematic Desensitization: A gradual process of diminishing phobias and fears with the introduction of relaxation using a hierarchy of fear inducing stimuli. 59 Pavlov Institute of Physiology Russian Academy of Sciences http://www.infran.ru/history_eng.htm 60 20
Questions Q9. How does Pavlov explain the physiological basis of stimulus generalization and discrimination? Q10. Why does Rescorla say that classical conditioning occurs due to contingency between - and not contiguity. Describe Rescorla (1966) study to elucidate this point. Q11. Explain in detail compound conditioning. Include in your answer overshadowing, blocking and overexpectation. 61 21