Discrimination & Generalization

Question 1

Operant antecedents

Answer 1

• Discriminative stimuli (SD) – signal that when present
  responses are reinforced; when absent responses are
  not reinforced; occasion setters
• Still don’t elicit behavior, just change probability
• Light (SD) : Press Lever (R) →Food (SR
  )
• Discriminative stimuli for punishment (SP
  ) – signal that
  when present responses are punished; when absent
  responses are not punishment
• Light (SDP) : Press Lever (R) → Shock (SP
  )
• Discriminative stimulus (antecedent), operant behavior
  (behavior), & consequence = three- term contingency

Question 2

Discriminative stimulus

Answer 2

• Individual is trained to give the target behavior only
  when a particular stimulus is presented
• Spray bottle: Barking →Sprayed
  SDP R SP
• Cop car: Speeding → Ticket
  SDP R SP

Question 3

• Signal extinction (S∆)

Answer 3

• Behavior is reinforced in the presence of the
  desired stimulus but not in the presence of other
  stimuli
• Kids at school:swearing → classmate approval
  SD R SR
  Grandparents:swearing → no approval
  SD/∆ R

Question 4

CC – OC overlap

Answer 4

• Tone (NS): Food (US)→ Salivation (UR)
• Tone (CS)→ Salivation (CR)
• Tone: Lever press → Food
  SD R SR
• Response matters
• Tone is CS to salivation, but SD for lever pressing

Question 5

Stimulus control

Answer 5

• Behavior consistently reinforced in the presence of a
  particular stimulus, that stimulus affects the probability of
  the behavior occurring
• These are essentially cues to behavior
• Cueing what consequences would be
• Presence of the discriminative stimulus (SD) affects
  probability of the behavior
• Does not elicit the behavior itself, just signals that
  reinforcement is available.
• Examples
• 2000 Hz Tone : Lever Press → Food
• Bar : Smoking Urge → Smoking

Question 6

Generalization

Answer 6

• Tendency for an operant response to be emitted in the
  presence of a stimulus that is similar to the
  discriminative stimulus (SD) for that response
• Example: If you have learned to beg for candy in a
  grocery store, you might also do it in a convenience
  store
• More similar the stimulus to the SD the more likely the
  response
• Example: Rat is rewarded with food for lever pressing
  in the presence of a 2000Hz tone. More likely press
  the lever in presence of 1800 Hz tone than 1000 Hz
  tone

Question 7

Generalization gradient

Answer 7

• Depiction of strength of
  responding in the
  presence of stimuli
  similar to the SD
• Strongest responding to
  the SD
• Steeper gradients = less
  generalization and more
  discrimination
• Shallow gradients = more
  generalization and less
  discrimination

Question 8

Stimulus Generalization

Answer 8

• Physical Similarity
• Similar context
• But what if learning context differs?
• Stimulus class or concept

Question 9

Stimulus class

Answer 9

• Common-element stimulus class
• Set of stimuli, all of which have some physical
  characteristic in common
  *All 4 legged animals are “dog”
  *All vehicles are “truck”
• Conceptual behavior – emitting behavior to all
  members of a common-element class, but not
  those that don’t belong to the class
• Stimulus Equivalence Class
• Set of completely dissimilar stimuli learn to
  respond to in the same way (learned to group)

Question 10

Discrimination

Answer 10

• Tendency for an operant response to be emitted
  more in the presence of one stimulus than another
• Opposite of generalization
• Example: If you have learned to beg for candy in a
  grocery store, but you don’t do it in a convenience
  store
• Example: Rat is rewarded with food for lever
  pressing in the presence of a 2000Hz tone. More
  likely press the lever in presence of 1800 Hz tone
  than 1000 Hz tone

Question 11

Discrimination training

Answer 11

• While the discriminative stimulus signals that
  reinforcement is available, other stimuli become
  signals that reinforcement will NOT be available.
• These other stimuli are called “discriminative
  stimuli for extinction”

Question 12

• Discrimination training (operant procedures)

Answer 12

• When responding is NOT reinforced in the
  presence of certain stimuli those stimuli become
  discriminative stimuli for extinction (symbol = S∆
  )
• Example
• 2000 Hz Tone (SD) : Lever Press (R) → Food (SR)
• 1200 Hz Tone (S∆) : Lever Press (R) → No Food (-)

Question 13

Effective Stimulus Discrimination Training

Answer 13

• Choose distinct signals
• Minimize opportunities for errors
• Maximize the number of trials
• Need multiple trials to learn the behavior
• Arrange for several reinforced responses in the
  presence of the SD
• When the S ∆ is presented, make the change from
  the SD very obvious and follow the rules for
  extinction for the behavior of concern
• Make use of rules: describe the
  contingencies
• Rules can speed up learning
• Wean the individual from the program
• Plan natural reinforcers
• Plan periodic assessments of behavior to make sure it is
  occasionally being reinforced and that the desired frequency of
  the behavior is being maintained in the presence of the SD

Question 14

Limitations of discrimination
training

Answer 14

• When discriminating SD from SΔ
  , Ps will make
  mistakes
• Can result in frustration, emotional behavior etc.
• Fading & errorless discrimination learning
• Can reduced number of errors to SΔ
  if:
• 1. SΔ
     is introduced early in training, soon after SD
• 2. SΔ
     is started weak then gradually strengthened
     (fading)
• Example
• Pigeons trained to peck at red key (VI 60-sec)
• Once behavior established 5 sec extinction intervals
  implemented (light key switched off)
• Reinforcement and extinction sessions gradually
  increased to 3-mins each
• Dark key then gradually illuminated with green tinge
• Almost no errors made to S Δ
  relative to control group

Question 15

Discrimination & Errorless training

Answer 15

• Practical application
• In humans
• Enhance learning of math skills (Haupt et al., 1975)
• Setting up study areas
• Helping with insomnia
• In animals

Question 16

Limitations to errorless
discrimination training

Answer 16

• Marsh & Johnson (1968)
• Pigeons trained to discriminate between red and blue keys using
  errorless discrimination procedure
• Other pigeons trained to discriminate using standard
  discrimination procedures
• Once discrimination learning had taken place the SD and S Δ were
  reversed
• Pigeons that learned to discriminate using standard procedures
  had little trouble learning the new task
• Pigeons that learned to discriminate using errorless procedures
  had extreme difficulty with the new task
• Standard task – adverse side effects in original learning but task
  produces greater flexibility if material requires subsequent modification