Stimulus Control of Behaviour

1. Stimulus Control of Behaviour

2. Stimulus Control • Differential responding and stimulus discrimination • Complex environment • “Signal” from the “noise” • What is important?

3. Train Responses per minute Test Bird 107 Bird 105 triangle circle Reynolds (1961) • Pigeons, operant chamber, compound key

4. Discrimination and Generalization • Differential responding • Stimulus discrimination • Similar responding • Stimulus generalization

5. Generalization Gradients • Train on one (or more) stimulus • Test on continuum (i.e., a “gradient”) of other, related stimuli • Plot on graph… Generalization Gradient • Tricky • Reinforcement problem • Extinction problem • Probe trials and extinction blocks

6. Training stimulus Gen. Grad.: Stimulus Control Responses Stimulus Continuum (e.g., wavelength of light)

7. Training stimulus Gen. Grad: No Stimulus Control Responses Stimulus Continuum (e.g., wavelength of light)

8. Spetch & Mondloch (1993) • Pigeons in localization task • Touch-screen • Peck at target area of 2cm2 • Target defined by landmarks • Tested to determine the landmarks that controlled the discrimination

9. Training Stimuli

10. Results: Pigeon C207

11. Results: Pigeon 271

12. Factors in Stimulus Control

13. Sensory Capacity • Organism’s sensory capacity determines what stimuli can control behaviour • E.g., ultraviolet stimuli for honeybee, but not for human • Physical orientation

14. Overshadowing • Competition among stimuli for access to learning processes • Higher intensity stimulus more easily conditioned • Speed of conditioning

15. However… • Stimulus element approach • Elements in a compound stimulus treated as distinct and separate components • Overshadowing: most salient stimulus gains control • Configural-cue approach • Compound stimulus treated as an integral whole • Overshadowing: generaliztion decrement

16. Configural-cue interpretation • Overshadowing due to degrees of generalization decrement from training to testing • No generalization decrement for control group • Overshadowing group learned weak-STRONG, but only tested on weak, so considerable generalization decrement • Evidence for both stimulus element and configural-cue approaches

17. Type of Reinforcement • Biological predispositions; belongingness • Species • Sometimes seasonal • E.g., stimuli associated with courtship disregarded outside of mating season

18. Force & LoLordo (1973) Tone & light Light • Training: • Group 1 • L/T … press pedal … food • Group 2 • L/T … press pedal … avoid shock • Test compound and individual components Tone Pedal Presses Group1 (food reinforcer) Group 2 (shock avoidance)

19. Instrumental Response Factors • Nature of the response required for reinforcement can affect stimulus control

20. Dobrzecka, Szwejkowska & Konorski (1966)

21. Learning Factors in Stimulus Control • Pavlov • Inherent properties of nervous sytem • Innate • Due to physical similarity of stimuli • Lashley & Wade (1946) • Explicit discrimination training required • Stimulus control learned • Stimulus generalization because animals have NOT learned the difference between stimuli

22. Stimulus Discrimination Training • In classical or instrumental conditioning • CS+ or CS-, S+ or S- • Stimuli explicitly associated with other stimuli or outcomes S+ S- Cummulative responses Time

23. Training and Stimulus Control • Use generalization gradient to determine degree of stimulus control • Need to determine the feature(s) of the discrimination procedure that controls the gradient

24. Jenkins & Harrison (1962)

25. Range of Discriminative Stimuli • Wide range of stimuli have been used in discrimination studies • Music, auditory frequencies, painting styles, geometric shapes, etc., etc. • Can use these discrimination studies to assess the sensory capability of species

26. Pigeon Art Appreciation • Watanabe et al. (1995) • Trained pigeons to discriminate between Monet and Picasso • Achieved high degree of accuracy • Pigeons generalized to other artists of the same style (Impressionist or Cubist)

27. What’s Learned • Spence’s (1936) theory • Learn about both S+ and S- • Stimuli treated separately • S+ represents excitation • S- represents inhibition • Test • Excitatory stimulus generalization gradient • Most response near S+ • Inhibitory stimulus generalization gradient • Least response near S-

28. Honig et al. (1963)

29. S+/S- Interactions • Interactions likely to occur between S+ and S- • Especially likely if using intradimensional discrimination • Stimuli from same stimulus continuum • Example seen in peak shift

30. Peak shift Peak Shift • Maximum responding on generalization gradient not to trained stimulus • With S+/S- training • Already seen in Jenkins & Harrison (1962)

31. Hanson (1959

32. Spence’s Interpretation • Opponent process system • S+ generates internal excitatory gradient • S- generates internal inhibitory gradient • Actual generalization gradient (i.e., measured behavioural response) due to net sum of excitatory and inhibitory gradients

34. S- S- S- S- S+ S- excitatory Hypothetical internal gradients inhibitory Actual generalization gradient (i.e., net sum) e.g., responses Stimulus continuum

35. Absolute/Relative Control • Absolute interpretations • Learn specifics of individual stimuli • Spence’s theory is an absolute theory • Relational interpretatsions • Learn relationship between stimuli

36. Training Testing transfer (relational) absolute S+ S- Transposition Task • Kohler (1939) • Can a relational rule be transferred to a new stimuli set?

37. Intermediate Size Problem • Gonzales, Gentry & Bitterman (1954) • Chimpanzees, visual display of squares • Chimps choose intermediate size on transfer test Training Transfer Test 9 9 7 4 4 1 S+

38. Training Technique • Simultaneous discrimination training • S+ and S- presented together • Successive discrimination training • S+ and S- presented alone on different trials • Relative stimulus control with simultaneous • Absolute stimulus control with successive

39. Stimulus Equivalence Training • Train subjects to treat dissimilar stimuli as similar • Training to generalize, not discriminate • Categorization learning

40. Herrnstein, Loveland & Cable (1976) • Pigeons • Presence/absence pictures • S+: item present • S-: item absent • Various S+ stimuli: water, trees, people

41. Stimuli for Water as S+ Condition S- S+

42. Results Trees Water People

43. Contextual Cues • Context cues can exert stimulus control • Perform behaviours appropriate to a given context

44. Siegel (1975) • Morphine tolerance • Home room and injection room • Same amount of morphine across 4 days • Conditional compensatory response to context cues of injection room

45. Perkins & Weyant (1958) • Two groups of rats run through two mazes, one white, one black; same maze layout • Half of each group tested in same colour maze, half in opposite colour maze • Poor performance for rats tested in opposite compared to same

46. 100 50 Avoidance (%) 0 12 24 36 48 60 72 84 Retention Interval (hr) Kamin (1957) • State-dependent learning • Rats; avoidance learning • Test at various retention intervals • Rats’ own internal physiology serves as context cue

47. Akins (1985) • Male quail sexual conditioning • Arena with two compartments • Sand floor, orange walls • Wire-mesh floor and walls, green ceiling • Individual subjects allowed to move back and forth in baseline • Less preferred compartment made CS+ • Conditioning • Experimental group: CS+ paired with sexually receptive female (US) • Control group: US only in home cage, never in CS+ compartment

48. Results Experimental % time spent in CS+ compartment Control 1 2 3 Preference Tests

49. Conditional Relations • Binary relations: between two events (CS-US, operant-outcome) • Modulator: a third event that determines the nature of a binary relation • Modulator signals a conditional relation

50. light light noise noise food food Modulators • Instrumental • S+: respond --> reinforcer • S-: respond --> no reinforcer • Classical • “Facilitators” or “occasion setters”, not excitatory or inhibitory conditional stimuli • CS = noise, US = food, modulator = light