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Differential Reinforcement: Stimulus Control & Shaping. Lesson 11. Modifying Behavior. Response variability Engage in many different behaviors Differential reinforcement Some Bs reinforced, some not Response selection Stimulus control Generalization & Discrimination Shaping
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Differential Reinforcement: Stimulus Control & Shaping Lesson 11
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 ~
Differential Reinforcement • Response differentiation • Differentiation of SD and SΔ • Contextual cues • SD: B successful outcome • SΔ: B unsuccessful outcome • Example: • switching lights for class ~
Differential Reinforcement • Example: Puzzle box • Contextual cues? • Possible responses? ~ B1: Flip left switch SDs B2: Flip middle switch B3: Flip right switch
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? ~
Stimulus Control • Generalization • similar stimuli similar response • Discrimination • after more experience • differential reinforcement • similar stimuli different response • Stimulus generalization gradient • lower similarity lower response ~
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 ~
Stimulus Generalization Gradient Hi SD Strength of Response Lo Shades of Blue
Stimulus Discrimination • Distinguish between 2 similar stimuli • One never reinforced: SΔ • 2 classes of Discriminative stimuli • SD • SΔ ~
SD vs SΔ • SD signals that B will be reinforced ~ SD(blue) : B (bar press) SR(food)
Stimulus Similar to SD • Response occurs SΔ(lighter blue) : B (bar press) no SR(food) • SΔsignals that B will not be reinforced ~
SΔ • After training (experience) • Signals that SR will NOT follow B SΔ(lighter blue) : no B (no bar press)
Before Additional Training: Generalization Hi SD Numberof Pecks Lo Shades of Blue
Generalization Discrimination Pecking not reinforced when SΔ present Hi SD SΔ SΔ Numberof Pecks Lo Shades of Blue
Generalization Discrimination Pecking not reinforced when SΔ present Hi SD Numberof Pecks SΔ SΔ Lo Shades of Blue
Generalization Discrimination Pecking not reinforced when SΔ present Hi SD Numberof Pecks SΔ SΔ Lo Shades of Blue
Stimulus Discrimination Pecking during SΔ diminishes Hi SD Numberof Pecks SΔ SΔ Lo Shades of Blue
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 ~
Shaping: Successive approximations • RFT if orients toward ~