Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
PSY 445: Learning & Memory Chapter 3: Classical Conditioning Pavlovian Conditioning Pavlov was a research physiologist, not a psychologist At age 33, earns MD Spends next 20 years studying the digestive system Russia’s first Nobel Prize winner in 1904 Novel work done over the final 30 years of his life that earns him his place in scientific history Ivan Pavlov (1849-1936) Definition of Classical Conditioning In classical conditioning, the organism learns a connection between two stimuli In other words, the organism learns that one stimulus predicts another stimulus A form of associative learning Learning in which connections are formed between internal representations of events (e.g., stimuli and responses) during learning. Procedure Classical conditioning is the presentation of two or more events in an experimentally determined temporal relationship Any change in responding to one of the events is seen as evidence of a learned association Definition of Classical Conditioning Unconditioned stimulus (US) In classical conditioning, this is the stimulus that elicits the unconditioned response (UR) without conditioning Conditioned stimulus (CS) In classical conditioning, this is the stimulus which comes to elicit a new response by virtue of pairings with the unconditioned stimulus Unconditioned response (UR) In classical conditioning, the automatic (involuntary), unlearned reaction to a stimulus Conditioned response (CR) A learned response elicited as a result of pairings between that NS and an UCS Pavlov’s Paradigm Pavlov’s Participants Methods of Studying Classical Conditioning Eyeblink Conditioning Skin Conductance Response Conditioned Taste Aversion Evaluative Conditioning Eyeblink Conditioning The procedure is relatively simple and usually consists of pairing an auditory or visual stimulus (CS) with an eyeblink-eliciting US For example, light might be paired with a mild puff of air to the cornea or a mild shock After many CS-US pairings, an association is formed such that a learned blink, CR, occurs and precedes US onset The magnitude of learning is generally gauged by the percentage of all paired CS-US trials that result in a CR In this video clip, experimenter paired puff of air with pencil tap Skin Conductance Response (SCR) Electrodes put on the arm or palm A loud unexpected noise or mild shock (US) will usually cause this response (OR) Soft tone or light may be presented before the US Several pairings Just the tone or light (CS) will produce the SCR (CR) Electrodes will be put on participants prior to presentation of CS-US pairings Conditioned Taste Aversion Typical Procedure Rats are given novel taste (saccharin-flavored water) is followed by an illness-producing drug Gastrointestinal distress Flavored water is again presented Typical Results Decrease or complete avoidance of the flavored water (CS) Evaluative Conditioning A change in liking, which occurs due to an association with a positive or negative stimulus Neutral stimulus is paired with something one likes or dislikes Is not reflex-evoking After these movies came out in 1980s, the hockey mask was never the same Evaluative Conditioning Typical Procedure An affective neutral stimulus is presented along with another stimulus that already evokes some type of affective evaluation For example, a word (NS) is paired with an bad odor (US) Typical Results Emotional tone of the neutral stimulus will change to correspond to the US The word (CS) will come to evoke a negative feeling (CR) from the person who has gone through this type of conditioning Evaluative Conditioning Hammerl, Bloch, & Silverthorne (1997) Procedure Scenic pictures were pre-rated Pictures that were originally rated as neutral (NS) were then paired (five trials) with either pictures that were rated low or rated high (US) Results When paired with the high-ranked pictures, the neutral pictures received more positive ratings then before; when paired with the low-ranking pictures they received less positive ratings then before Thus, the originally neutral pictures become the CS and the resultant ratings of these pictures become the CR Evaluative Conditioning Limitations Doesn’t fit classical conditioning pardigm completely Reliance just on verbal reports is questionable Some believe the changed preferences are based on conscious knowledge; not automatic responses What stimuli can serve as CSs? Exteroceptive Stimuli Stimuli involving events outside the body that stimulate the sensory receptors Examples of exteroceptive stimuli include sounds, sights, smells, touch sensations, tastes, and the like Interoceptive Stimuli Stimuli inside the body that reflect some change in an internal state Examples of interoceptive stimuli include body sensations such as a full bladder or empty stomach Razran (1961) Conducted a proprioceptive conditioning experiment in which exteroceptive stimuli (dials) were paired with interoceptive stimuli (bladder distension) Exteroceptive stimuli became CS leading to CR What stimuli can serve as CSs? Contextual Stimuli The place or environment where training occurs are readily conditioned ○ Fear of dentist’s office Temporal Stimuli The passage of time since the last US serves as the CS for the next US ○ Marquis (1941) delayed feeding of infants from usual 3-hour interval Circadian Stimuli Conditioning of time of day can lead to different CRs What stimuli can serve as USs? Stimuli that have either biological significance or acquired significance work effectively as a US Basic Phenomena of Conditioning Acquisition Extinction Spontaneous Recovery Generalization Discrimination Basic Phenomena of Conditioning Acquisition When the organism first learns the connection between the CS and the US, it is said to be in the stage of acquisition The initial gain in response strength is large on each trial, and then it levels out at the end of the acquisition period. See graph Basic Phenomena of Conditioning Acquisition Control Procedures – its important to employ these conditions to protect against confounding variables Unpaired Control Experimental group gets paired CS-US; control gets CS and US separately Truly Random Control CS and US are each separately programmed to occur randomly in time during the experimental sessions along with the usual pairing of CS-US Basic Phenomena of Conditioning Extinction The decline or disappearance of the CR in the absence of the US Presentation of CS alone Basic Phenomena of Conditioning: Extinction US ---------------------------------------------- UR NS ----------------------------------------------- NO RESPONSE NS + US -------------------------------------- UR * This is repeated several times CS ------------------------------------------------ CR Extinction process is initiated: CS ----------------------------------------------- CS ----------------------------------------------- CS ----------------------------------------------- CS ----------------------------------------------- CR CR (less response than before) CR (less response than before) CR (less response than before) Eventually we get……….. NS --------------------------------------------- NO RESPONSE (bell) (no salivation) Basic Phenomena of Conditioning Spontaneous Recovery An extinguished CR will temporarily reappear if after a time delay the CS is presented again even without the UCS This is a reappearance of a CR after extinction despite no further CS-UCS pairings Apparently, extinction does not eliminate the CS-US association; just suppresses it Trial 11 represents a two-week rest period Spontaneous Recovery What happens next? Extinction continues CS-US pairing Basic Phenomena of Conditioning Generalization After a CR is acquired, stimuli that are similar but not identical to the CS also will elicit the response The greater the similarity between a new stimulus and the CS the stronger the CR will be Conditioned to tone of F Basic Phenomena of Conditioning Discrimination Organisms can be conditioned to learn to differentiate among similar stimuli Even a similar tone will not produce a response in certain situations ○ For instance, if two tones are continuously presented but only Tone 1 is paired with the US then CR will only appear when Tone 1 is presented The Role of Contiguity This is the belief that the critical factor in determining whether or not classical conditioning would occur was timing The most important thing to control in a classical conditioning experiment was that the CS and the US should be close together in time Does the sequence matter? Forward Pairing CS-US Strong conditioning Simultaneous Pairing CS/US No conditioning Backward Pairing US-CS Weak conditioning Other factors effecting conditioning Prior Exposure Latent inhibition reduces conditioning effect Compound CSs Usually weaker conditioning to two CSs conditioned together than when done one at a time Surprise The Blocking Effect See next slide The Blocking Effect Kamin (1969) Experiment 1: Phase 1 Phase 2 Phase 3 Tone ---- Shock Tone/Light ----Shock AM: Tone---? * This is repeated several times PM: Light---? Rescorla-Wagner Model This model explains the Blocking Effect Other factors effecting conditioning CS-US Relevance Belongingness – the idea that certain CSs and USs seem to belong together Belongingness Procedure Rats drink flavored water from tubes that flashed light and made noise when the tubes were licked… Group 1: ○ Rats were given electric shocks to their feet two seconds after beginning to drink Group 2: ○ Rats were exposed to X rays (which made them sick) while they drank Later, both groups were tested with: A tube of unflavored water producing lights and noise A tube of flavored water that was not producing lights and noise ○ Rats are basically given a choice between these two tubes to drink from Garcia & Koelling (1966) Belongingness Garcia & Koelling (1966) Results Group 1 (rats that had been shocked) avoided the tube producing the lights and noise while Group 2 (rats that had been made sick) avoided only the flavored water Interpretation Evidently, rats (and other species) have a built-in predisposition to associate illness mostly with what they have eaten or drunk (Group 2 rats) and to associate skin pain mostly with what they have seen or heard (Group 1 rats) This is an example of preparedness Conditioned Inhibition A CS becomes associated with the absence of the US For example, knowing when food is NOT available Second-Order Conditioning A new NS can become a new CS Sensory Preconditioning Two CSs are paired in first phase with no US For example, tone and light One of the CSs is paired with food in the second phase For example, tone and food In third phase, the other CS (the one never paired with the US) is tested For example, light CR is witnessed Difference between higher order and sensory preconditioning The difference is when the two CSs are paired In higher-order conditioning, the CS2CS1 pairing happens AFTER the US has been paired with the CS1 In sensory preconditioning, the CS2CS1pairing happens BEFORE the US has been paired with the CS1 Preparatory Response A theory of learning that a different form of conditioning, instrumental conditioning, controls the acquisition and performance of conditioned responses CR are rewarded (a reinforcement theory) Learning in the Brain Cerebellum appears to have the key function related to the conditioning process Considered the final destination for association to take place Lesions in this area of the brain prevent tone-toeyeblink conditioning The Role of Awareness in Conditioning Early Pavlovian ideas would say awareness was not necessary for conditioning Automatic processes Conflicting studies Some reports of CS-US contingency suggest that awareness can be a factor Secondary tasks are often employed Sometimes participants in these experiments report they are aware of CS-US connections But this does not correlate with the conditioning that is actually taking place Extensions of Conditioning Drug Tolerance Drugs have less of an effect when taken repeatedly (less of a high) Drug users crave more of the drug despite its lessening effects It appears that certain drugs trigger our body to call upon its defenses against the effects of the drug Extensions of Conditioning Siegel, Hinson, Krank, & McCully (1982) Demonstrated that classical conditioning principles might be in effect during druginjecting episodes Possible reason for overdoses? Extensions of Conditioning Siegel’s theory… US ---------------------------------------------- UR (drug) (anti-drug defenses) NS ----------------------------------------------- NO RESPONSE (injection ritual) (no defenses) NS + US -------------------------------------- UR (injection ritual) + (drug) (anti-drug defenses) * Repeated several times CS ----------------------------------------------- CR (injection ritual) (anti-drug defenses) Siegel et al. (1982) Extensions of Conditioning Familiar setting----------------------- anti-drug defenses (usual time, place, etc) (body reacts) New setting ---------------------------- no defenses (place, time are different) (body doesn't react) The same dosage now becomes an overdose – they get too high as their bodies have been fooled by the new procedure Siegel et al. (1982) Extensions of Conditioning In this experiment laboratory rats were preconditioned to a tolerance of large doses of heroin… Procedure: ○ Lab rats given daily intravenous injections for 30 days ○ Placebo or heroin given either in “animal colony” or alone in “white noise” room on alternate days ○ Counterbalance of treatment: For some rats: heroin in WN; placebo in AC For others: heroin in AC; placebo in WN Control group received only placebo in different rooms on alternate days Siegel et al. (1982) So this then gives us 3 main Groups: Group 1: Received heroin in the Colony room (their normal living quarters) and placebo in the Noisy room the next day Group 2: Received placebo in the Colony room (their normal living quarters) and heroin in the Noisy room the next day Group 3: Received placebo in the Colony room (their normal living quarters) and placebo in the Noisy room the next day All rats were then injected with a large dose of heroin (15 mg/kg) Siegel et al. (1982) But does it depend on the room? But the room in which this potentially lethal dose of heroin was administered was varied between subgroups of rats… On Day 31: Group 1A were injected with heroin in the Colony room ○ Where they had received all their previous injections of heroin Group 1B were injected with heroin in the Noisy room ○ Where they had never received any previous injections of heroin Group 2A were injected with heroin in the Noisy room ○ Where they had received all their previous injections of heroin Group 2B were injected with heroin in the Colony room ○ Where they had never received any previous injections of heroin Group 3A were injected with heroin in the Colony room ○ Where they had no previous injections of heroin Group 3B were injected with heroin in the Noisy room ○ Where they had no previous injections of heroin Siegel et al. (1982) Results: Death Rate Group 3 showed substantial mortality (96%) A group with prior exposure in the same cage showed tolerance (only 32% died) A group with the same history of exposure, but tested in an environment not previously associated with heroin showed higher mortality (64%) Siegel et al. (1982) Results: Death Rate Results 50% increase in death rate in new room Rats show "room-specific" tolerance Siegel (1984) In a follow-up study, overdose victims who had survived were interviewed and 70% reported they had changed environmental conditions Siegel et al. (1982) Conditioning with Drug USs Siegel (1991) Reviewed studies that tested conditioning after drug exposure by replacing the drug with a placebo injection Monitoring of body’s conditioned response to the injection procedure (CS) in the absence of the drug (US) Physiological reactions are sometimes opposite of what you would expect from receiving the drug For example, morphine raises body temperature, placebo lowers it; morphine reduces pain, placebo increases pain sensitivity This leads to speculation that conditioning can lead to the development of conditioned responses that are the opposite of unconditioned responses Immune System studies.. Ader & Cohen (1975) Originally intended as a taste aversion experiment they found some incidental results related to our immune system response Rats drank a saccharin solution immediately before the injection of cyclophosphamide, an immunosuppressive drug that also has aversive gastrointestinal side effects Following this pairing, rats avoided drinking the saccharin solution Immune System studies Ader & Cohen (1975) Results related to immune functioning The saccharin CS also developed capacity to suppress immune functioning as a CR Immune System studies O'Reilly & Exon (1986) These researchers paired a saccharin taste (NS) with the immunosuppressing cyclophosphamide (UCS) One of cyclophosphamide's natural effects is the reduction of natural killer-cell activity Natural killer-cells are one of an organism's first defenses against the development of malignant tumors When they find a cell that has been infected with a virus or one that has become cancerous, they engulf and destroy it When they presented saccharin to rats, it resulted in a conditioned taste aversion as well as a conditioned reduction in natural killer-cell cytotoxicity Immune System studies Bovbjerg & Redd (1990) Participants 20 female ovarian cancer patients Procedure Chemotherapy given to patients in hospital setting Patients return home within 24-48 hours after treatment Hypothesis Classically conditioned anticipatory nausea and vomiting (ANV) and anticipatory immune suppression (AIS) Immune System studies US ------------------------------------------- UR (chemo) (nausea/vomiting) NS -------------------------------------------- NO RESPONSE (hospital) (no reaction) NS + US ----------------------------------- UR (hospital) (chemo) (nausea/vomiting) * This is repeated several times… CS --------------------------------------------- CR (hospital) (nausea/vomiting) Bovbjerg & Redd (1990) Immune System studies US ------------------------------------------- UR (chemo) (immunosuppressive) NS -------------------------------------------- NO RESPONSE (hospital) (no reaction) NS + US ----------------------------------- UR (hospital) (chemo) (immunosuppressive) * This is repeated several times… CS --------------------------------------------- CR (hospital) (immunosuppressive) Bovbjerg & Redd (1990) Immune System studies Results Participants experienced both decreased immune function and increased nausea when they returned to hospital setting Immune suppression occurred after being brought to the hospital but before the next round of chemotherapy actually began Could the immune suppression be a CR? In certain disorders, an overactive immune system attacks the body and thus suppression becomes a desirable treatment. ○ Therefore, could a placebo in this case have a practical application? Bovbjerg & Redd (1990) Behavioral Medicine Implantable cardiac defibrillator (ICD) delivers electric shock to its users whenever irregular heart rate occurs Some report intense shocks that can cause them to fear places or situations Pairing of shock with a variety of CSs The conditioning theory of phobias… Watson & Raynor (1920) Behavioral psychologists John Watson and grad assistant Rosalie Raynor taught an 11-month old infant to become afraid of a gentle white laboratory rat Little Albert reacting to mask worn by John Watson This illustrates generalization Preparatory-Response Theory The purpose of CR is to prepare organism for the UCS The dog salivates to the tone so as to get ready for the presentation of the food The rat freezes in response to the light so it is ready for the painful shock Taste-aversion learning Preparedness leads us to acquire certain fears that have high survival value Preparatory-Response Theory Limitations Fears are not limited to preparedness stimuli Dental anxiety, etc. Fears tend to be age-related Young children more easily develop animal fears; teenagers more easily develop social fears, etc. Extinction as a therapy… Exposure treatments can again be utilized to help treat phobias Systematic desensitization Counterconditioning occurs as phobia (CS) is paired with US that is incompatible with the phobia Jones (1924) Removed a fear of rabbits in a young child by pairing ice cream (US) with presentations of the rabbit (CS) Credits Some slides prepared with the help of the following websites: http://ibs.derby.ac.uk/~keith/b&b/tolerance.ppt http://salmon.psy.plym.ac.uk/year3/DrugAbuse/drugtolerance.htm http://drmillslmu.wikispaces.com/file/view/Psych310RomanticRedPr esentation.ppt http://gcuonline.georgian.edu/field_ps432_40/Terry03.htm dogsbody.psych.mun.ca/2250/lecture%206.ppt people.uncw.edu/dworkins/psy41703ppt/Chapter11.ppt www.columbia.edu/cu/.../courses/.../powerpoints/lect5_cc2.ppt