1. Learning Factors in Stimulus Control

2. Learning Factors Why does stimulus generalization occur? – CS transfers to other stimuli with similar physical properties (Pavlov) – Inability to discriminate between stimuli (Lashley & Wade) Stimulus Discrimination Training – Role of experience in producing stimulus control – A stimulus discrimination procedure can establish stimulus control Experience with CS-US establishes the CS as the discriminative stimuli for the US Experience with (S-O) establishes when the reinforcer is available – Example using eyeblink conditioning Within subject design Half of the trials were A+ (2000 Hz tone) signals followed by US The other half were B- (8000 Hz tone) signals without US Figure 8.5 Some generalization between A and B tones at first Then gradual discrimination between the tones

3. The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved. Auditory Stimuli 2000 HZ 8000Hz

4. Stimulus Discrimination Training Everyday experiences illustrate the role of learning Red light, Green Light, Yellow light combination on traffic lights Vanilla, Chocolate, Strawberry etc. flavors of ice cream Cabernet Sauvignon, Pinot Noir, Chardonnay, Merlot, Zinfandel wines Discrimination training with instrumental conditioning Terminology Stimulus follow by the reinforcer is S D Stimulus not followed by the reinforcer is S  Procedures Sequential discrimination training Alternating trials of S D or S  Need to keep them in short-term memory to compare them Simultaneous discrimination training S D and S   are presented together Easier to make the discrimination so it is easier to learn

5. Effects of Discrimination Training and Stimulus Control Experience can produce very fine discrimination between stimuli – Use generalization gradients to test effects of discrimination training Jenkins & Harrison (1960, 1962) – Trained pigeons to respond to tones Grp 1: S+ (1000-cps) S- (no tone)1000-cps Grp 2: S+ (1000-cps) S- (950-cps)1000-cps950-cps Grp 3: no discrimination training 1000-cps only – Generalization Testing with tones from 300 to 3500 Hz Figure 8.6 Grp 3 (Control grp): flat generalization gradient Grp 1 & 2: – stimulus control by tone frequency over responding – steepest gradient (strongest stimulus control) was shown by Grp 2.

6. The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved. FIGURE 8.6 Generalization gradients of responding to tones of different frequencies after various types of training. Each data point represents the percentage of all test responses that occurred to a particular test stimulus. Prior to testing, one group of pigeons received discrimination training in which a 1,000-cps tone served as the S+ and the absence of tones served as the S−. Another group received training in which a 1,000-cps tone served as the S+ and 950-cps tone served as the S−. The control group did not receive discrimination training before the generalization test. (From “Effects of Discrimination Training on Auditory Generaliztion,” by H. M. Jenkins and R. H. Harrison, 1960, Journal of Experimental Psychology, 59, pp. 246–253; also from “Generalization Gradients of Inhibition Following Auditory Discrimination Learning,” by H. M. Jenkins and R. H. Harrison, 1962, Journal of Experimental Analysis of Behavior, 5, pp. 435– 441.)

7. Discrimination Training Focused on Interoceptive Cues External stimuli – – Tones lights shapes from simple to complex in a variety of modalities Internal stimuli “interoceptive cues” – – related to thirst, hunger, arousal, pleasure – Of interest in drug discrimination studies Schall et al., 1996 Stimulus Control by Drug Stimuli – Before discrimination training : 3.0mg/kg cocaine alone – Discrimination training with S+ (3.0 mg/kg) and S- (saline) – Generalization test shown in Figure 8.7 – Discrimination training increases stimulus control by the internal sensations created by cocaine

8. The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

9. Discrimination Training Focused on Compound or Configural Cues Configural as a combination of two or more simple stimuli – Pizza sign with colors, shapes and words – Can configural cues act as stimulus control? Procedures used to test configural cues – Positive patterning Reinforce to stimuli presented simultaneously (AB+) (noise, flashing light) Do not reinforcer either of them separately (A-) or (B-) – Negative patterning Do not reinforcer stimuli presented simultaneously (CD-) (tone, steady light) reinforcer each of them separately (C+) or (D+) – See Table 8.2 – Harris 2008 Four different stimuli, noise, tone, flashing light, steady light as CS Six types of trials (see above) intermixed – Responded more to (AB)with positive patterning – Responded more to (C) or (D) with negative patterning – See Figure 8.8

10. The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved. noise Flashing light tone Steady light

11. The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.

12. What is learned in discrimination learning? Spence’s theory of discrimination learning Do animals learn about S+, about S-, or both S+ and S-? – S+ rule: "respond only when S+ is present" – S- rule: "stop responding only when S- is present" – S+/S- rule: "respond to S+, and not to S-" Excitatory conditioning of S+ – Excitatory stimulus generalization gradient centered around the value of S+ Inhibitory conditioning of S- – Inhibitory stimulus generalization gradient centered around the value of S-

13. What is learned in discrimination learning? Drug discrimination study Kearns 2005 see figure 8.9 – Experimental group Tone (S+) with Lever pressing on VI schedule for cocaine Light (S-) no reinforcement – Control group Tone/light with Lever pressing on VI schedule for cocaine on half of the trials Light only on half of the trials – Summation Testing Tone only Tone / light combination – combination of tone and light reduces responding – Evidence that light (S-) has inhibitory properties Similar to inhibitory conditioning (CS-) in classical conditioning – Suggests that drug addiction could be treated with cues that are negative discriminative stimuli. Any reliable cues that predict drug is not available Could be context “place” cues

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15. Interaction Between S+ and S-: Peak-Shift Effect Interdimensional discrimination training uses different stimulus dimensions (e.g., color vs pitch, time vs number) Intradimensional discrimination training uses same stimulus dimension (e.g., red vs green, 1000-cps vs 950-cps) – which results in generalization gradients with a special feature – “peak shift” Hanson (1959) Generalization Testing see Figure 8.10 – Discrimination Training: with different colors of light Grp1: S+ (550-nm) S- (555-nm) Grp2: S+ (550-nm) S- (590-nm) Grp3: S+ (550-nm) only i.e. no discrimination training – Results Grp3: excitatory gradient centered at 550-nm Grp2: high rate of responding to 550-nm but peak of responding displaced to 540-nm Grp1: lower rate of responding to 550-nm than Grp2 or Grp3, and a shift in peak responding to colors between 530-540-nm

16. The Principles of Learning and Behavior, 7e by Michael Domjan Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved. FIGURE 8.10 Effects of intradimensional discrimination training on stimulus control. All three groups of pigeons were reinforced for pecking in the presence of 550-nm light (S+). One group received discrimination training in which the S− was a 590-nm light. For another group, the S− was a 555-nm light. The third group served as a control and did not receive discrimination training before the test for stimulus generalization. (From “Effects of Discrimination Training on Stimulus Generalization,” by H. M. Hanson, 1959, Journal of Experimental Psychology, 58, pp. 321–333.)

17. Spence’s Explanation of Peak-Shift displacement of responding in a stimulus generalization gradient away from the S+ in a direction opposite the S- It is a function of the similarity of S- to S+ and results from any intradimensional discrimination – Excitatory stimulus generalization gradient centered around the value of S+ – Inhibitory stimulus generalization gradient centered around the value of S- – Actual responding to a stimulus value on the dimension reflects generalized excitation to that stimulus value minus generalized inhibition to that stimulus value – The exact shape of the excitatory and inhibitory gradients has a big impact on predictions – Peak shift requires that the excitatory gradient overlap with the inhibitory gradient (S+/S- similarity, and spread of the distributions) – Spence Peak Shift Figure Spence Peak Shift Figure – Annimated Power Point demonstration of Spence's explanation Annimated Power Point demonstration of Spence's explanation

18. Alternative Accounts of Peak-Shift Viewing stimuli as single elements or as configural cues Spence's explanation is based on absolute properties of individual stimuli Alternative view – processing the relationship between or relative difference of several stimuli – for example discrimination based on the difference between S+ (1000 Hz) vs S- (950 Hz)

19. Stimulus Equivalence Training Difference versus Equivalence – Discrimination training can make animals respond differently to stimuli that they would normally respond to in the same way – Can a training procedure be developed that would make animals respond similarly to stimuli that they would normally respond to differently? Learning procedures to increase stimulus generalization is stimulus equivalence training. Perceptual concept learning which will be covered in chapter 12 – Concepts like "water" "tree" "fish".etc – Reinforce the same response to different photos containing the perceptual category but not to photos in which the category is absent Reinforce any photo of tree but not reinforce photos of water or fish

20. Stimulus Equivalence Training Functional equivalence training: Table 8.3 – Initial Training For different types of stimuli in set A another set of four designs in set B reinforced for making the same response (lever pressing) to any of the stimulating in set A or set B this should establish equivalency between the two sets – Reassignment Designs in set A are also trained with a different response (pull a string) for reinforcement – Test Test the patterns from set B with the alternative response pulling on a string if they associate pattern B with pulling the string evidence of equivalents between set A and set B

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22. Equivalence Class An equivalence class has the following three properties – Reflexivity: A = A, B = B, C = C. – Symmetry: A --> B, B --> A. – Transitivity: A --> B, B --> C, A --> C For example; if A is the word “Apple” ; if B is an apple; if C is a picture of apple Equivalence training can be used to improve verbal skills of individuals with intellectual disabilities verbal labels in human language facilitates equivalence class formation – Transferring a type of response from set a to set B is an example of emergent relations – can be used to improve verbal skills if a rose is a flower and a flower is a plant than a rose is a plant Which is an example of an emergent transitive relationship