Download Stimulus Control & Procedures for Visual Discriminations: Study by Wilson, et al. and more Study notes Communication in PDF only on Docsity!
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:
- Stimulus-prompt procedures
- 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:
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
