Learning Psychology PDF

Learning Psychology PSYC-2502 Dr. Emel Erdogdu [email protected] 1  - 04 - Classical Conditioning: Foundations Habituation / Sensitization Forms of learning that require only a single stimulus Repetition of stimuli →...

Learning Psychology PSYC-2502 Dr. Emel Erdogdu [email protected] 1  - 04 - Classical Conditioning: Foundations Habituation / Sensitization Forms of learning that require only a single stimulus Repetition of stimuli → decrease: Habituation Arousal → increase: sensitization  İn real life events do not occur isolated Habituation and sensitization is not enough for complex behavior Learning to predict events in the environment and learning what stimuli tend to occur together help us interact more effectively with our environment cloud –rain Engine – car Smile –friendly Coffee machine - coffee  Stimulus-Response Learning Classical conditioning - Pavlov Operant conditioning - Skinner Classical conditioning (CC) The simplest mechanism whereby organisms learn about relations between one event and another is classical conditioning. CC is a process whereby we learn to predict when and what we might do in response to a certain event involved in the learning of new emotional reactions (e.g., fear or pleasure) to stimuli that have become associated with a significant event A previously neutral stimulus that would not elicit a behavior is associated with a stimulus that stimulates behavior – resulting in the learned stimulus to also elicid such behavior Ivan Pavlov (1849 - 1936) «Accidentally found» as extension of his research on the processes of digestion Workers recognized increase of stomach juice when feeder was present → psychic secretions Later: theory of learning and neural bases İncrease of Stomach juice → sold as treatment for diseases ! The Discoveries of Vul’fson and Snarskii Object learning Worked in Pavlov’s lab Vul’fson: salivation in Dogs in relation to dry,wet and sour food, sand. Later sight of such food was enough to elicit salivation in certain amounts. Snarskii: gave black lemon water → any black water or just pure sight of it caused salivation The visual features of the stimuli were learned Learning and manipulating features of same object is difficult in an experiment, hence Pavlov continued to experiemnt with association between different stimuli The Classical Conditioning Paradigm Salivation in response to food placed in the mouth is measured A bell is presented before the food is given Does the bell elicit salivation?  Unconditioned/Conditioned stimulus - response Unconditioned Stimulus (US) Unconditioned response (UR) (natural response) Neutral stimulus Pairing (NS + US) Conditioned stimulus (CS) Conditioined response (CR) stimuli and responses whose properties do not depend on prior training are called unconditional, and stimuli and responses whose properties emerged only after training are called conditional.  Characteristics of Classical Conditioning Response acquisition: CR is learned (salivation in response to the bell) Extinction: CR decreases and ultimate disappearance, if US and CS are never paired again Spontaneous recovery: unexpected reoccurance of CR after extinction when hearing a bell Stimulus generalization: not bell, but other sound may elicit the CR Example Lets say a dog bites you and you become afraid of dogs. What the CS/US and related UR/CR? Dog bite → US fear → UR Dog → CS Fear of dogs → CR Emotional responses are shaped by classical conditioning Conditioning of the US can be appetetive or aversive Desire vs avoidance Aversive → very fast (phobias – anxiety) Car phobia Little albert Before , had only little fears Rat was paired with loud sound of a hammer Strong emotional response towards rat Stimulus generalization Fear of furry things Fear conditioning + stimulus generalization  Clinical Examples of Classical Conditioning Nausea Conditioning among Cancer Patients Hospital room (neutral) Cancer drug (US) → Nausea (UR) Drug at hospital room Hospital room (CS) → Nausea (CR) Stimulus generalization Child afraid of nurses in white lab coat shows similar crying response to visiting grandmother in white coat Animal models for fear conditioning Freezing in rats İnvisibility for predator acquisition of freezing in Common defense mechanism response to an auditory CS Record with camera using electro shock (US) In addition to freezing, two other indirect measures of fear-induced immobility are also used in investigations of fear conditioning. Both involve the suppression of ongoing behavior and are therefore referred to as conditioned suppression procedures. 1- animals are deprived of water, hence want to drink in the box; measure how they supress behavior due to fear conditioning 2- animals learned to press lever for food; how is learned behavior supressed due to fear conditioning  Eyeblink Conditioning Blink due to puff of air or loud sound etc. Early component of startle response extensively investigated in studies with human participants Study aging, Alzheimer’s disease, fetal alcohol syndrome, and other disorders Ivkovich et al. (1999) 5 month old infants; 750ms tone Group 1: every 12 sec a tone ends with puff of air to eyeball Group 2: 4-8 sec between tone and air CS? US? UR? CR?  Results Ivkovic İmportant findings 1. Classical conditioning requires pairing of the CS and US (temporal) 2. Learning in infants is evident at second session while it was learned during the first session What are the neural bases of the eyeblink response ?  Class. Cond. - Learned helplessness Negative association of aversive stimulus (electro shock) and inability to escape Subsequently animals do not try to escape in presence of aversive stimuli → becoming hopeless and apathetic Might be model for depression Subject has tried but failed to control external events, and becomes depressed when presented with new life stressor More on this topic in operant conditioning  Clinical Examples of Classical Conditioning Learning to Be a Drug Addict Drug user consistently uses similar accessory (syringes, cigarettes, coffee) in similar (ritualistic) setting (room), these stimuli can become a CS over time and act as signals which warn the body that the drug (US) is about to be ingested The body then physiologically prepares a compensatory response that allows the body to counteract the drug’s effects This reaction becomes the CR If experienced drug user takes drug in new environment, many environmental CS’s will not be present and the body will not have a compensatory response → overdose Therapeutical Applications of Classical Conditioning Unwanted behaviour can be «unlearned» Treating phobias Exposure therapies → CS without US allowing extinction Classical conditioning can also decrease our arousal and attraction to stimuli. This principle is used in aversion therapy, which attempts to condition an aversion (a repulsion) to a stimulus that triggers unwanted behavior by pairing it with a noxious US → smoking, pedophiles Sign Tracking and Goal Tracking Pavlov’s - salivation and other highly reflexive responses. But, does classical conditioning occur only in reflex response systems? → NO Sign Tracking (autoshaping) paradigm changed the view! Animals gain lots of info about possible food source through cues (movement, sound, smell) Sign Tracking and Goal Tracking Brown and Jenkins (1968) Birds were given access to food for 4 sec The key light was illuminated for 8 sec immediately before each food delivery. → pigeon started pecking the key light source !!! Presenting the key light at random times or unpaired with food did not lead to pecking Results do not change even when food and light source are 90 cm apart went to key light rather than food cup when the CS is on  Sexual US → still  Sign Tracking and Goal Tracking individual differences in sign tracking 8 sec one lever left or right (CS) Followed by food in food cup (US) Sign tracking (CR-1) Goal tracking (CR-2)  Individual differences in sign tracking are correlated with individual differences in impulsivity and vulnerability to drug abuse Genetically based Sign trackers show greater psychomotor sensitization to cocaine, greater activation of the dopamine reward circuit, and elevated plasma corticosterone levels Learning Taste Preferences and Aversions sensory aspects of the food serve as CSs that become associated with the postingestional consequences of eating, which are USs. Preference is learned if a flavor is paired with nutritional repletion or other positive consequences Aversions are learned often after poisioning (evolution) One time is enough Event hours after eating patients have been shown to acquire aversions to foods eaten before a chemotherapy session Learned aversion may also cause annorexia Long-delay taste-aversion Smith & Roll (1967) Two groups of rats Water deprived Saccharin solution exposed to X-ray for illness at different levels (subgroups 0-24h) Control (sham group) Animals exposed to radiation within 6 hours after tasting the saccharin solution showed a profound aversion to the saccharin flavor (less than 20 %)  Evaluative conditioning In evaluative conditioning, our evaluation or liking of a stimulus is changed by having that stimulus associated with something we already like or dislike. Banana and Vanilla flavour→ paired with sugar and bitter flavor 1. Advertisement uses evaluative conditioning → induce a preference for the product 2. Liking someone → more likely to like someone when he/she participates in activities you enjoy  Form of CC we talked about so far Excitatory conditioning: organisms learn a relation between a CS and US Common Pavlovian Conditioning Procedures Conditioning trial: time from the start of the CS to the start of the US within a conditioning trial Repetitions Intertrial interval (time from the end of one conditioning trial to the start of the next trial interstimulus interval (CS- US intervall): time from the start of the CS to the start of the US within a conditioning trial  Measuring Conditioned Responses Record test trial of CS before pairing (baseline – without US) Quantify CR: Magnitude (how much does CR occur) Frequency (how often does CS cause CR) Latency (how soon CR occurs after CS onset)  Control Procedures for Classical Conditioning no prior stimulus exposures make sure that the observed change in behavior could not have been produced by prior separate presentations of the CS or the US. pseudo-conditioning:If exposure to just the US produces increased responding to a previously ineffective stimulus Random control procedure present US randomly during CS and intertrial interval (not that successful) Explicitly unpaired control CS and US in separate trials  Effectiveness of Common Conditioning Procedures Different conditioning procedures are good for different design Short-term → fear (simultaneous presentation would result in movement away (avoid) from CS) The view that classical conditioning involves not only learning what to expect but when to expect it is called the temporal coding hypothesis Other than excitatory Inhibitory Pavlovian Conditioning learn to predict the absence of the US A conditioned inhibitor is a signal for the absence of the US Why would you want to predict the absence of something? → comfort Child is unpredictabily abused Panic attack Next attack in war Exposure to unpredictable aversive stimulation is highly aversive and results in stomach ulcers and other physiological symptoms of stress Stress reduction techniques involve creating a predictable period of safety A panic attack is a sudden sense of fear or discomfort, accompanied by physical symptoms Other example for inhibitory conditioning Fear of dog that bit you (US) İnhibitory conditioning results in inhibition of some behavior → Presence of inhibitory stimulus reduces / inhibits behavior Dog → excitatory conditioned stimulus for fear Dog owner → inhibitory conditioned stimulus for fear  There are two major procedures used to produce conditioned inhibition and special tests that are necessary to detect and measure conditioned inhibition Procedures for Inhibitory Conditioning General rule: inhibitory conditioning and inhibitory control of behavior occur only if there is an excitatory context for the US in question →signs that provide meaningful information and influence what we do only if they indicate the absence of something we otherwise expect to see →«Out of gas» sign at station → conditioned inhibitor (CS-)  1- Pavlov’s Procedure for Conditioned Inhibition Trial A creates an exitatory context for Trial İmportance of an excitatory context B to be possible; the inhbitory conditioning Trial A: excitatory conditioning → CS+ (tone) predicts US Trial B: inhibitory trial → CS- (light) is paired with CS+ in absence of US CS– a conditioned inhibitor or signal for the absence of the US. a) Red traffic light → CS+ DANGER, dont cross 1. Traffic police → CS- inhibits the fear of traffic/cars → Trust, pass 2. Police gestures inhibit, or block, your hesitation to cross the intersection because of the red light. b) Child will seek arms of parents for safety c) Adults may pray; therapy CS- is a safety signal during (potential) danger 2 -Negative CS-US Contingency or Correlation Does not involve an explicit excitatory stimulus or CS+. CS- signals a reduction in the probability that the US occurs US appears periodically; CS is followed by the predictable absence of the US A negative correlation or contingency means that the US is less likely to occur after or during the CS than at other times İf a child is bullied (US) in absence of teacher → teacher is CS- Measuring Conditioned Inhibition Excitatory stimuli elicit new CRs (salivation, eye blink) Easy to measure within (1) Bidirectional Response Systems (heart rate, temperature→ they can rise or fall) Other inhibitory stimuli are hard to detect because they usually do not create behavior above normal level → eye blinking will not get less than normal level «better» : The (2) Compound-Stimulus, or Summation Test simple idea that conditioned inhibition counteracts or inhibits conditioned excitation. CS– disrupts or suppresses responding that would normally be elicited by a CS+  Cole et al. (1997) Light ending with Shock (A+); light without shock (AX-) → X: tone 28 A+ (excitatory) ve 56 AX-(inhibitory) Parallel other experiment B: sound. Does X also has effect in B? (B+) & BX- Animals have 5 sec to lick water BY: B and other sound than X → no effect X is a general safe signal İndirect measure as it is also effective in of how long it took them to B, although it was only drink for 5 sec. pairedly presented in A. The higher the bar, the more interruption there were due to fear X inhibited conditioned fear elicited by A and B. X inhibited conditioned fear elicited by A and B.