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103_7_full - PSYC 103 Winter 2011 Lecture 7 DISCRIMINATION...

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Unformatted text preview: PSYC 103 Winter 2011 Lecture 7 DISCRIMINATION LEARNING CHAPTER 6 Sign (or releasing) stimulus Three-spined stickleback attacks any object with a red l belly z , but not a colorless model Stickleback generalization and discrimination Stimulus Control: Generalization Generalization: responding to one stimulus transfers to other (usually similar) stimuli Generally, as the training and test stimuli become more different responding will decline, producing what is called a generalization gradient Measuring the degree of stimulus control? generalization Training stimulus Generalization Gradient 50 100 150 200 250 300 350 Responses Wavelength (nanometers) pigeons were reinforced for pecking a 580 nm lit key (orange-yellow) on a VI schedule A test session was then given where many different colored key lights were presented in extinction (from Guttman & Kalish, 1956) Generalization gradients Weak stimulus control Strong stimulus control Generalization and discrimination generalization discrimination Discrimination is the opposite of generalization; changes in a stimulus result in different levels of responding Determinants of stimulus control Sensory capacity : is the organism sensitive to the stimulus? e.g. range of hearing for humans 20-20000 Hz Sensory orientation : the stimulus must reach the sense organ. Motivation : Can bias attention in favor of certain stimuli under certain conditions Stimulus Intensity or Salience : The presence of an intense stimulus can interfere with the control of behavior by a weaker cue, called overshadowing 50 dB noise is overshadowed by a coincident light CS Stimulus control: Learning Factors Stimulus Discrimination procedures : any procedure that provides differential reinforcement in the presence of different stimuli In Pavlovian conditioning: CS+ (green light) paired with US CS- (red light) paired with no US Rat Basketball l Motivation z effects Foree & LoLordo (1973) Two groups of pigeons trained to press a bar in the presence of a light+tone compound stimulus One group of pigeons reinforced with food One group of pigeons reinforced with the avoidance of shock 5 10 15 Mean responses Tone Shock-avoidance reinforcement Food reinforcement Light Tone + Light Pigeons tie visual cues to food and auditory cues to shock 1. Pigeons trained with food responded more to the light alone than to the tone alone 2. Pigeons trained with shock-avoidance responded more to the tone alone than to the light alone Differential Reinforcement Training with differential reinforcement can have effects beyond the actual stimuli used in the training procedure In the absence of discrimination training a flat generalization curve is seen Discrimination training produces as steep generalization curve Stimulus Control Peak Shift Several groups of pigeons trained to peck different colored key lights The control group is trained with only one stimulus, a 550 nm key light, reinforced on a VI schedule The experimental groups are trained with 2 key lights, the 550 nm light...
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This note was uploaded on 03/24/2012 for the course PSYC 103 taught by Professor Pearlberg during the Spring '07 term at UCSD.

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103_7_full - PSYC 103 Winter 2011 Lecture 7 DISCRIMINATION...

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