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Differential Reinforcement: Stimulus Control

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Lo. Stimulus Discrimination. Distinguish between 2 similar stimuli. One never reinforced: S? ... Lo. Shades of Blue. Pecking not reinforced when S? present. S? ... – PowerPoint PPT presentation

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Title: Differential Reinforcement: Stimulus Control


1
Differential Reinforcement Stimulus Control
Shaping
  • Lecture 12

2
Modifying Behavior
  • Response variability
  • Engage in many different behaviors
  • Differential reinforcement
  • Some Bs reinforced, some not
  • Response selection
  • Stimulus control
  • Generalization Discrimination
  • Shaping
  • Changes in response probability

3
Differential Reinforcement
  • Response differentiation
  • Differentiation of SD and S?
  • Contextual cues
  • SD B ? successful outcome
  • S? B ? unsuccessful outcome
  • Example
  • switching lights for class

4
Differential Reinforcement
B1 Flip left switch
SDs
B2 Flip middle switch
B3 Flip right switch
  • Example Puzzle box
  • Contextual cues?
  • Possible responses?

5
Differential Reinforcement Continuous Variations
in Behavior
  • On a single behavior
  • Variations in strength of extent
  • e.g., baking time for cookies
  • Not enough ? doughy
  • Too much ? burnt
  • SDs for good cookies?
  • SDs for bad cookies?
  • Other examples?

6
Stimulus Control
  • Generalization
  • similar stimuli ? similar response
  • Discrimination
  • after more experience
  • differential reinforcement
  • similar stimuli ? different response
  • Stimulus generalization gradient
  • lower similarity ? lower response

7
Stimulus Generalization
  • Present new stimulus
  • Similar to SD or CS
  • associative
  • Response occurs
  • even though not reinforced
  • or paired with US
  • Novel stimulus
  • presented only a few times

8
Stimulus Generalization Gradient
Hi
SD
Strength of Response
Lo
Shades of Blue
9
Stimulus Discrimination
  • Distinguish between 2 similar stimuli
  • One never reinforced S?
  • 2 classes of Discriminative stimuli
  • SD
  • S?

10
SD vs S?
  • SD signals that B will be reinforced

SD(blue) B (bar press) ? SR(food)
11
Stimulus Similar to SD
  • Response occurs

S? (lighter blue) B (bar press) ? no
SR(food)
  • S? signals that B will not be reinforced

12
S?
  • After training (experience)
  • Signals that SR will NOT follow B

S? (lighter blue) no B (no bar press)
13
Before Additional Training Generalization
Hi
SD
Numberof Pecks
Lo
Shades of Blue
14
Generalization ? Discrimination
Pecking not reinforced when S? present
Hi
SD
S?
S?
Numberof Pecks
Lo
Shades of Blue
15
Generalization ? Discrimination
Pecking not reinforced when S? present
Hi
SD
Numberof Pecks
S?
S?
Lo
Shades of Blue
16
Generalization ? Discrimination
Pecking not reinforced when S? present
Hi
SD
Numberof Pecks
S?
S?
Lo
Shades of Blue
17
Stimulus Discrimination
Pecking during S? diminishes
Hi
SD
Numberof Pecks
S?
S?
Lo
Shades of Blue
18
Systematic Shaping
  • Bar pressing natural behavior for rats?
  • Differential reinforcement of successive
    approximations
  • Reinforce Bs similar to part of desired B
  • Progressively shift to closer approximations
  • B SR contingency

19
Shaping Successive approximations
20
Shaping Successive approximations
  • RFT if orients toward

21
Shaping Successive approximations

22
Shaping Successive approximations

23
Shaping Successive approximations
24
Shaping Successive approximations
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