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Stimulus Control & Procedures for Visual Discriminations: Study by Wilson, et al., Study notes of Communication

A study conducted by Wilson, et al. on Stimulus Control and procedures to facilitate visual discriminations. The study explores methods for facilitating discrimination during picture-card communication training using stimulus fading and enhanced consequences. background information on visual discrimination, stimulus control, and previous comparison studies. It also presents the methods, results, and conclusions of the study.

What you will learn

  • How does stimulus control affect responding differently to different stimuli?
  • What is visual discrimination and why is it critical for learning?
  • What are the advantages of stimulus-prompt procedures over response-prompt procedures in facilitating discrimination?
  • How does the number of fading steps and conducting probe trials impact the transfer of stimulus control?

Typology: Study notes

2021/2022

Uploaded on 09/12/2022

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Stimulus Control
&
Procedures to Facilitate
Visual Discriminations
David M. Wilson, Ph.D., BCBA-D
Georgian Court University
Agenda
Visual Discrimination
Stimulus Control
Review procedures to transfer stimulus control
Brief review of comparison studies
Study: Procedures to facilitate discrimination
Summary
Questions
Visual Discrimination
Discrimination: differentially responding in the
presence of different stimuli
Critical for learning
Discrimination among complex stimuli
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Stimulus Control

Procedures to Facilitate

Visual Discriminations

David M. Wilson, Ph.D., BCBA-D

Georgian Court University

Agenda Visual Discrimination Stimulus Control Review procedures to transfer stimulus control Brief review of comparison studies Study: Procedures to facilitate discrimination Summary Questions Visual Discrimination

 Discrimination: differentially responding in the

presence of different stimuli

 Critical for learning

 Discrimination among complex stimuli

Visual Discrimination

 Students must discriminate academic materials:

  • Colors & Shapes
    • Image credit: https://creativemarket.com/blog/2013/12/02/10-basic-elements-of-design Visual Discrimination
  • Numbers & Letters http://studentmedia.uab.edu/wp-content/uploads/2012/09/123ABC.jpg Visual Discrimination
  • Words & Pictures Image credit( (http://www.uniqueteachingresources.com/reading-sight-words.html

Stimulus Control

S+S-

“Press Me” REINFORCEMENT Stimulus Control

S+ S-

Bar 1 REINFORCEMENT Bar 2 Stimulus Control

 Differential Reinforcement can be effective to

establish stimulus control

 Limitations:

  • Errors (responses to S-) occur during teaching
  • Prolonged teaching sessions
  • Learners may never acquire the correct responses

 Alternative teaching methods must be considered

Errorless Learning

 Errorless learning or Errorless discrimination

Training involves the use of a fading procedure to

establish a discrimination so that no errors occur.

 Fading involves the gradual removal of:

  • Stimulus prompts
  • Response prompts Errorless Learning Trials 1Trials 11Trials 16Trials 21Trials 26Trials 31- 10 - ---- (^1520253035) A B Transfer of Stimulus Control

 Transfer of Stimulus Control:

  • Procedures to fade prompts
  • Transfer stimulus control from a prompt to a feature of the target stimulus

 2 Categories:

  1. Stimulus-prompt procedures
  2. Response-prompt procedures

Stimulus Shaping Stimulus-Prompt Procedures

 Advantages:

  • Enhancements are made to the actual target stimuli
  • Facilitates transfer to relevant stimulus features

 Disadvantage:

  • Making enhanced stimuli takes time
  • Teaching time may be extended  Extra-stimulus prompt:
  • Not related to the discrimination task  Point prompt  Most-to-least prompting  Least-to-most prompting  Verbal prompt Response-Prompt Procedures

 Prompt Delay:

  • Incorporated into extra-stimulus prompt procedures
  • Inserts a delay between target stimuli presentation and extra-stimulus prompt
  • Reinforcement arranged to favor responses before the prompt

Prompt Delay

 “Touch A”

A B

Response-Prompt Procedures

Response-Prompt Procedures

 Advantages:

  • Most-to-least produces fewer errors, rapid acquisition
  • Least-to-most allows for independent responding

 Disadvantages:

  • Extra-stimulus prompts are not relevant to target stimuli
  • May be difficult to fade

Other Considerations

 Restricted Stimulus Control (aka stimulus

overselectivity)

  • Possible feature of autism
  • Responding under control of irrelevant feature of a complex stimulus  Position  Specific therapist/teacher  Tear in the left hand corner of an instructional stimulus Other Considerations

 Addressing restricted stimulus control

  • Eliminate irrelevant feature (if possible)
  • Transfer control to relevant feature of target stimulus
  • Alternate between teaching trials of target stimulus with problem stimulus

Examination of Procedures to

Facilitate

Discrimination of

Picture-Communication Cards

Wilson, D.M., Iwata, B.A.

Bloom, S.E.

PECS (Bondy & Frost, 1994, 2001)

 Augmentative communication system

 Utilizes picture cards containing

communicative referents

 6 Training Phases (1-3 critical):

  • Phase 1: Requesting
  • Phase 2: Generalization
  • Phase 3: Discrimination PECS Curriculum (Frost & Bondy, 1994, 2001) PECS

 PECS usage is rapidly acquired:

  • Bondy and Frost (1994, 2001)

 Increases vocal communication:

  • Kravits, Kamps, Kemmer, and Potucek (2002)
  • Charlop-Christy, Carpenter, LeBlanc, & Kellet (2002)

 Decrease inappropriate behaviors:

  • Charlop-Christy, Carpenter, LeBlanc, & Kellet (2002)

 What about participants who have difficulty

acquiring PECS usage?

Discrimination Baseline

  • S+ & S- presented:
    • S+ → access to corresponding stimulus
    • S- → access to corresponding stimulus
    • No response → next trial
  • S+/S- positions alternated
  • Criterion for continuation: failure to meet

criterion of 90% unprompted correct

responses for 3 consecutive sessions

Comparison Methodology  One S+/S- pair taught via stimulus fading  Another S+/S- pair taught via enhanced consequences  Training sessions alternated  Criterion: 90% responding to S+ for 3 consecutive sessions under original S+/S- conditions Stimulus Fading

 Enhanced S+ card:

  • Distance
  • Size

 Fading steps:

  • Fading criterion: S+ responding 90% or higher for 3 consecutive sessions
  • Distance: 10 cm, 20 cm, 30 cm
  • Size of card: 10 cm^2 , 7.5 cm^2 , 5 cm^2 , 2.5 cm^2

Picture Cards S+ S- Stimulus Fading S+ Enhanced Consequences

 Rate, delay, magnitude, quality:

  • Magnitude (Hoch, McComas, Johnson, Faranda, & Guenther, 2002)
  • Quality (Mace, Neef, Shade, & Mauro, 1996) Enhanced Consequences

 Magnitude:

  • Response to S+: larger quantity of reinforcers (e.g., 3 jellybeans)
  • Thinning: S+ responding 90% or higher for 3 consecutive sessions

 Quality:

  • S- replaced with stimulus never selected during the single-stimulus preference assessment

Summary of Results

 Stimulus fading:

  • Victor acquired 1 S+/S- discrimination
  • Perry acquired 3 S+/S- discriminations

 Enhanced Consequences:

  • Victor acquired 1 S+/S- discrimination
  • Al acquired 2 S+/S- discriminations Conclusions

 Stimulus fading and enhanced

consequences will facilitate visual

discrimination

 Enhanced consequences establishes

stimulus control

 Stimulus fading assumes stimulus control

Study 2

 Purpose: evaluate the effects of stimulus fading

combined with enhanced consequences to train

discrimination between two picture cards

Study 2: Methods

 Participants and Setting:

  • 5 participants w/ developmental disabilities
  • Sheltered workshop or Special-Education School

 Procedures identical to Study 1 (except

training)

 Multiple baseline

 Criterion: 90% responding to S+ for 3

consecutive sessions

Stimulus Fading & Enhanced Consequences

 Enhanced S+ card

 Magnitude/Quality enhancement

 Fading steps:

  • Fading criterion: S+ responding 90% or higher for 3 consecutive sessions
  • Distance: 10 cm, 20 cm, 30 cm
  • Size of card: 10 cm^2 , 7.5 cm^2 , 5 cm^2 , 2.5 cm^2 ; Reinforcer Magnitude: 3,2, Discrimination Training (^10200) 30405060 708090 100 Andrew (^1020300) 405060 (^100708090) Billy (^10200) 30405060 708090 100 Donald (^10200) 30405060 708090 100 (^0 10 20 30 40) SESSIONS 50 60 70 80 90 100 Kevin (^10200) 30405060 708090 100 % of Trials Responding with S+ David BL 16 5 4 3 2 1 BL 26 54 3 2 1 Fading^ Stimulus+ ConsequencesEnhanced 6 5 4 3 2 1b1a 6 54 3 2 1b 1a 6 5 4 3 21 2 1b 1a 6 5 4 3 2 1b 1a 6 5 4 3 2 1b 1a 6 5 4 3 21 6 5 4 3 21 6 5 43 21 6 5 4 3 21 BL 3

Limitations

 Training time

  • Study 1: avg. 30 sessions
  • Study 2: avg. 23 sessions

 Number of fading steps

 Picture card preparation time

 Used only edible stimuli

Thank You wilsond@georgian.edu