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Chapter 7

Chapter 7 part 1.docx

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University of Toronto Scarborough
Steve Joordens

Chapter 7: Introduction - In chapter 4 there may have been an impression that behaviour is controlled by neural circuits that are fixed and unchanging What is behaviour? - Our behaviour is changeable in response to certain experiences. What is learning? - Learning: is an adaptive process in which the tendency to perform a particular behaviour is changed by experience - As conditions change, we learn new behaviours and eliminate old ones - Learning cannot be observed directly, it can only be inferred from changes in behaviour but: o Not all changes in behaviour are caused by learning. i.e. performance on an examination can be affected by mental conditions such as fatigue, fearfulness, or preoccupation - Also, learning may occur without noticeable changes in observable taking place. i.e. you may have received training in how to change a flat tire in a drivers ed class but your behaviour will not change unless you have to change a car tire. What is the effect of experiences on the brain? - Experience alters the structure and chemistry of the brain. These alterations affect how the nervous system responds to subsequent events. What is performance? - Performance: is the behavioural change produced by the internal changes brought about by learning. In other words, it is the evidence that learning has occurred. o This is imperfect evidence because there are other factors such as fatigue and motivation. What are the three kinds of learning? 1. Habituation 2. Classical conditioning 3. Operant conditioning - All three kinds involve cause and effect relations between the environment and behaviour. Habituation What is orienting response? - Orienting response: any response by which an organism directs appropriate sensory organs (eyes, ears, nose) toward the source of a novel stimulus. i.e. to turn your head to respond to sound What is habituation? - Habituation: the simplest form of learning; learning not to respond to an unimportant event that occurs repeatedly. i.e. if the noise occurs repeatedly, we will eventually ignore it - Even very primitive animals have learned to habituate Who is George Humphrey? And what did his experiment outline? - George Humphrey (1933) described a simple experiment he had conducted using land snails. - Humphrey was one of the scholars that studied with Wundt before coming to Canada to teach the new science of psychology; his interest in snails was certainly a change in pace from what he learned in Germany) - Humphrey placed several snails on a glass plate, and tapped sharply on the plate. - All of the snails immediately and reflexively withdrew into their shells-- showing a snails version of how we might react to a sudden and scary scene in a movie. - Humphrey waited until all of the snails re-emerged and then gave the plate another tap. This time not all of the snails with drew. - With each further tap, fewer snails withdrew into their shells, until, after many taps none would for each snail the probability of reacting to the tap decreased with each exposure to it. How does habituation occur? Like its relation to stimulus? And why is habituation useful? - Habituation makes sense from an evolutionary perspective. - If a once-novel stimulus occurs again and again without any important results, the stimulus has no significance to the organism - Obviously, responding to a stimulus of no importance wastes time and energy. Consider what would happen to a snail in a rainstorm if the withdrawal response never habituated: The snail would remain in its shell until the rain stopped falling. (which I think is really funny for some reason) - And consider how distracting it would be to have your attention diverted every time a common house hold noise occurred Rankin and colleagues showing that habituation is not due to other factors than learning: - They used a tiny worm from the class Nematoda (e.g. Giles, Rose, and Rankin, 2005 - Like the snails these worms respond to a tap on the substrate in which they move by withdrawing or retreating. - It is known that this response occurs through neurons that respond to the mechanical stimulus of the tap - However, these worms also withdraw from sources of heat, using much the same neural pathway - In 1997, Wicks and Rankin used showed that they could produce habituation to tap- elicited withdrawal without affecting withdrawal to a heat stimulus. - You could say that these worms learned something about the tap, and that they distinguished this learning something about the tap, and that they distinguished this learning from their reaction to a source of heat. - These worms could do this with only 302 neurons in their entire nervous system. What is short term habituation? - Short term habituation: the simplest form of habituation which is temporary. - For example, if we tap a snails shell over and over until a withdrawal response ceases, when we tap it again after a few days we will find that the withdrawal response reoccurs and continues for several more taps. - It takes just as long for habituation to occur as it did before. - If we repeat the experiment every few days the same thing will happen; the snail does not remember what happened previously What is long term habituation and where is it most common? - Animals, particularly those who have complex nervous systems are capable of long-term habituation. i.e. a hunting dog may be frightened the first few times it hears a sound of a shotgun, but it soon learns not to respond to the blast. - This habituation carries across from day to day and even from one hunting season to the next - Likewise, your behaviour has habituated to stimuli that you have probably not thought about for a long time. i.e. when people move to new houses they often complain about being kept awake by unfamiliar noises. But after a while, they no longer notice them What distinguishes short-term habituation from long-term habituation? - The pattern of experience plays an important role. - When stimuli are massed into quick repetitions, habituation is rapid but short term, when these stimuli are presented in small groups that are spaced in time habituation is slower but long term Classical Conditioning - Habituation involves learning about single events What is classical conditioning? - Unlike habituation, classical conditioning involves learning about the conditions that predict that a significant event will occur. - we acquire much of our behaviour through classical conditioning. For example, if youre hungry and smell a favourite food cooking your mouth is likely to water - ex. In a B-grade horror movie, and the heroin is walking through an abandoned warehouse when the background sound changes to very scary and you know that some menace is about to pop out of the shadows. Yet, although you expect a surprise and relish anticipation you find your muscles tensing. - Your fear is the behaviour that shows you have learned the predictive relationship between the music and the upcoming fright. - It doesnt take many experiences with this paring of music and fright to produce the kind of reaction we all associate with horror films Pavlov s Serendipitous(unexpected) Experiment (p.s. im sorry this is so long I couldnt make it any shorter) Who is Pavlov and what were his major discoveries? - In December 1904, the Russian physiologist Ivan Pavlov was considered one of the foremost scientists of his time - Pavlovs chief ambition as a physiologist was to discover the neural mechanisms controlling glandular secretions during digestion - He measured the secretions during the course of a meal - For example, he inserted a small tube in a duct in an animals mouth and collected drops of saliva as they were secreted by the salivary gland. - It was while conducting routine studies of salivation in dogs that his interest in digestion became forever sidetracked by a serendipitous discovery. - Pavlovs strategy was to study salivary processes in individual dogs over many sessions. - During each session, he placed dry food powder inside the dogs mouth and then collected the saliva - All went well until the dogs became experienced participants. After several testing sessions, the dogs began salivating before being fed, usually as soon as they saw the laboratory assistant enter the room with the food powder. - What Pavlov discovered was a form of learning in which one stimulus predicts the occurrence of another. - In this case, the appearance of the laboratory assistance predicted the appearance of food. - Instead of ignoring this phenomenon or treating it as a confounding variable to be controlled, Pavlov designed experiments to discover exactly why the dogs were salivating before being given the opportunity to eat. - He suspected that salivation might be triggered by stimuli that were initially unrelated to eating - Somehow, these neutral stimuli came to control what is normally a natural, reflexive behaviour. After all, dogs do not naturally salivate when they see a laboratory assistant. - Pavlovs new ambition was to understand the variables tha
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