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Chapter 3

Learning and Behaviour-Chapter 3

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Wilfrid Laurier University
Anneke Olthof

1 Learning and Behaviour-Chapter 3 Classical Conditioning: Foundations -if human and nonhuman animals only had the behavioural mechanisms described in chapter 2, they would remain rather limited in the things that they could do -habituation and sensitization involve learning about just one stimulus, but events in the world do not occur in isolation -cause and effect relationships in the world ensure that certain things occur in combination with others -the simplest mechanism whereby organisms learn about the relations between one event and another is classical conditioning The Early Years of Classical Conditioning -systematic studies of classical conditioning began with Ivan Pavlov, and was also discovered by Edwin TwitmyerTwimyer repeatedly tested the knee-jerk reflex of college students by sounding a bell .5 seconds before hitting the tendon below the knee cap; after several trials he found that the bell was sufficient enough to elicit the knee jerk reflex in some students -Pavlov’s classical conditionings were an extension to his work with digestion in dogs; found that stomach secretions occurred when the dogs saw the people feeding them or even the sight of food -stomach secretions elicited by food-related stimuli were referred to as psychic secretions because they seemed to be a response to the expectation or thought of food The Discoveries of Vul’fson and Snarskii -performed the first systematic studies of classical conditioning in Pavlov’s laboratory, focusing on the salivary glands which are the first digestive glands that deal with the breakdown of food -Snarskii used artificial substances such as dying lemon water black, and found that after several encounters with the black sour water, the dogs would salivate to plain black water or the sight of a bottle containing black liquid -orosensory stimuli are substances that produce distinctive textures and taste sensations in the mouth— these are the types of things that they used -object learning: learning associations between different stimulus elements of an object; dogs learning to associate visual features with orosensory features The Classical Conditioning Paradigm -basic procedure involves two stimuli; tone/light and food -conditional stimulus: (CS) a stimulus that does not elicit a particular response initially but comes to do so as a result of becoming associated with an unconditioned stimulus bell or the tone -unconditional stimulus: (US) a stimulus that elicits a particular response without the necessity of prior training food -conditional response: (CR) the response that comes to be made to the conditioned stimulus as a result of classical conditioning salivation -unconditional response: (UR) a response that occurs to a stimulus without the necessity of prior trainingsalivation Experimental Situations -most of the experiments are now carried out with rats, rabbits and pigeons 2 Fear Conditioning -major focus has been on the conditioning of emotional reactions—believes that infants are limited in their reactions, therefore Watson and Rayner conditioned a fear response in a nine-month old infant Albert to the presence of a white lab rat -found that the little boy acted with alarm when he heard a loud noise, therefore they used the unconditional alarming stimulus to condition fear to the white rat -after two conditioning trials he became reluctant to touch the rat and after 5 trials he showed strong fear responses to the rat -most of the research on fear and conditioning has been conducted on lab rats and mice, using a shock as the US through the grid floor, the CS may be a tone or a light or the contextual cues of the place where the aversive stimulus has occurred -rats show their fear by freezing -investigators use two different indirect methods of mobility, both involve suppression of ongoing behaviour and are referred to as conditioned suppression -conditioned suppression: suppression of positively reinforced instrumental behaviour (eg. Lever pushing for food pellets) caused by the presentation of a stimulus that has become associated with an aversive stimulus (also known as conditioned emotional response (CER))  in one case, ongoing behaviour that is measured is licking a drinking spout that contains water (animals are slightly water deprived) and therefore lick readily when placed in an experimental chamber—if a fear CS (ex. tone) is presented their licking behaviour is suppressed and they take longer to make a specified number of licks; latency to complete a certain number of licks is measured as the behavioural index of conditioned dear -lick suppression procedure: baseline is licking a water spout by thirsty rats, the presentation of a fear conditioned CS slows down the rate of drinking  another prominent technique for the indirect measurement of conditioned fear is the conditioned emotional response procedure (CER) where in this procedure rats are first trained to press a response lever for food reward in a small experimental chamber, this lever press activity provides the baseline for measurement of fear—once the rats are lever pressing at a steady rate, fear conditioning is introduced, consisting of a tone or a light paired with a brief shockeventually come to suppress their lever pressing during the CS -greater disruptions in lever pressing would be a score that is lower than 0.5 indicating that a fear has been conditioned -keep in mind that a suppression rate of 0 indicates zero responding during the CS, which represents the greatest possible suppression of lever pressing Eyeblink Conditioning -eye blink reflex is an early component of the startle response and occurs in a variety of species -tends to be a very active area of research because it provides a powerful tool for the study of problems in the developing of aging and Alzheimer’s disease -study of eye blinking in 5 month old infants; CS was a tone presented for 750 milliseconds, the US was a gentle puff of air delivered to the right eyefor one group of infants the CS always ended with a puff of air with conditioning trials occurring every 12 seconds apart; the second group received the same number and distribution of CS and US presentations, but for them the CSs and USs were spaced 4-8 seconds apart in an explicitly unpaired fashion (second group served as a control)—each group received 2 training sessions that were 2 weeks apart -found that the rate of eye blinks did not differ statistically during the first experimental session, however the paired group responded at a significantly higher rate from the beginning of the second session therefore it shows that classical conditioning requires the pairing of a CS and US 3 -responding to the CS did not develop in the unpaired control group -neurological investigations of eye blink conditioning have been conducted primarily in studies with domesticated rabbits because they are sedentary and rarely blink in the absence of an air puff or irritation of the eye -rabbits are placed in a chamber where the CS (tone) is presented for half a second and is followed immediately by the delivery of the US (puff of air)as the CS is repeatedly paired with the US, the eye blink response is also paired with the CS -find that rabbit blink conditioning is very slow taking several hundreds of trials for substantial levels of conditioned responding Sign Tracking -there was a belief that classical conditioning occurs only in the reflexive response system but in recent years, this restrictive view has been abandoned -sign tracking: movement toward and possibly contact with a stimulus that signals the availability of a positive reinforce, such as food (also known as autoshaping) -animals tend to approach and contact stimuli that signal the availability of food, in natural environments food can be predicted by appearance at a distance or sight and noises -sign tracking is investigated in the laboratory by presenting a discrete localized visual stimulus just before each delivery of a small amount of food -tracking of signals for food is dramatically illustrated by instances in which the signal is located far from the food cup -did an experiment dealing with quail who will readily copulate in captivity where they used a wooden block that would be lowered from the ceiling 30 seconds before a female copulation partner was released (the CS and the female were presented at opposite ends of the chamber)found that the bird approached the CS rather than the location of where the female was released as the association of the CS with sexual reinforcement made it such an attractive stimulus that the birds were very drawn to it -sign tracking occurs only in situations where the CS is localized and therefore can be approached and tracked -for sign tracking to occur, the CS has to be of the proper modality (normal pattern) and configuration— ex. with rats, they went to the light in one instance, but if a tone was used they would go to their food bowl Learning What Tastes Good or Bad -conditioned taste aversion is learned if ingestion of a novel flavor is followed by an aversive consequence such as indigestion or food poisoning and in contrast a preference may be learned if a flavour is paired with nutritional repletion or other positive consequences -flavour illness experience can produce an aversion in just one trial—in 20% of cases people were sure that their sickness was not due to the food they ate, however they still developed an aversion to it which indicates that aversion learning can be independent of the rational thought process -animal research indicates that the growth of tumours can result in the conditioning of aversions to food ingested during the disease -food aversion may also be linked with anorexia, as they experience digestive disorders after eating certain foods -taste aversion learning is a result in the pairing of a CS (taste) and a US (drug) -strong taste aversions can be learned with just one pairing of the flavour and illness and another interesting thing is that learning occurs even if the illness does not occur until hours after the exposure -long-delay learning of taste aversions probably evolved to enable human and other animals to avoid poisonous foods that have delayed ill effects 4 -a flavour can be made unpalatable by pairing it with another taste that is already disliked, therefore placing a neutral flavour with something that is already liked will make that flavour preferable -evaluative conditioning: our evaluations or liking of a stimulus changes by virtue of having that stimulus associated with something we already like or dislike used extensively in the advertising industry Excitatory Pavlovian Conditioning Procedure
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