autism: article review methods gast ctd ptd
TRANSCRIPT
Ault, M. J., Gast, D. L., & Wolery, M. (1988). Comparison of progressive and constant time delay procedures in teaching
community-sign word reading. American Journal of Mental Retardation, 93, 44-56.
SPED 8370
Dr. David Gast
Gabriela Walker
Time delay procedure
• Touchette (1971) – form discrimination• At least one session at 0-s delay –
– Natural cue/task direction and the controlling prompt are presented simultaneously
• CTD – the delay interval is held constant throughout the instructional sessions
• PTD- the delay interval gradually increases• 5 types of possible responses
Purpose of the study
• Determine the effectiveness of CTD and PTD for teaching community-sign reading to students with MO
• Evaluate the efficiency of the two procedures relative to e/o.
Method - Subjects
• Rita, F, 8.08 yrs. CA, 3.58 MA, 41 IQ
• Ned, M, 10.5 yrs CA, 4.5 MA, 44 IQ
• Elliot, M, 11.25 yrs CA, 5.25 MA, 48 IQ
• All subjects dx. MO ID based on AAMR classification system (Grossman, 1977)
• Attended self-contained classroom
• All Ss had previous exp PTD, not CTD
Method - Subjects and Setting
• Pre-requisites– Visual and auditory acuity– Sit and attend for min. of 15 min.– Verbally imitate spoken words– Perform identity match– Respond correctly to “What word?”– Reinforcers exchanged with tokens
• Setting – self-contained 7x8 m, sped teacher as instructor, 4 other students also present in the room, table separated by a partition
• Instructional arrangement: 1:1
Method - Materials
• Instructional materials (12 words):– 12.5 x 9 cm white index cards– 1 word: hand printed in capital letters with
black ink – 1 word per 1 card
• Generalization materials (36 symbols):– 12.5 x 9 cm photographs of sign words found in
natural settings
Method - Procedures
• Screening: * to identify functional sign words to be taught to
each participant– 44 signs, 3 sessions over 2 consec. days– 12 target words divided CTD/PTD = difficulty
• Data collection: only correct anticipations counted toward criterion
Method - Procedures• General:
– 2 sessions/day, 20 trials each session– CTD & PTD switched to control for time of day and
order effects– For both procedures, 2 words were presented
simultaneously (conditional discrimination)– General Att. Response followed by task direction
“What word?”– Reinforcement: praise and token– Incorrect resp. : verbal reprimand + in-seat time-out– Intertrial interval: 3 sec.– Controlling prompt: verbal model of the word name
Method - Procedures
• Probe:– Prior to instruction & after S met criterion– General Att. resp. followed by task direction– Reinf.: descriptive verbal praise & token (VR3)
–correct resp. & between trials for attendance– Incorrect resp. ignored
Method - Procedures
• Progressive time delay:– 20 trials/session; 10 trials/word
– 2 words intermixed, w/ no more than 3 consec.
– 1 session at 0-s; the remaining 1-s increment
– Ceiling at 8-s delay
– Correct resp. : “Good”+name the word+token
– Incorrect resp.: “No, wait”+remove materials+ looked away for 10 sec.
– Criterion of each pair: 100% correct anticipations for 3 consec. sessions with CRF schedule
Method - Procedures• Constant time delay:
– Same as PTD, except for the delay interval– 1 session at 0-s delay– The remaining at 5-s delay
• Intermix: – To prepare Ss for probes– “After Ss reached criterion on each word pair with both
procedures, the 4 words were randomly intermixed in 20 trial sessions” (p. 48)
– Identical procedures as during probes– Criterion set at 100% correct anticipations for 2 consec.
while on CRF and 100% correct for 2 consec. while on VR3
Method - Procedures
• Review trial:– During instruction on 2nd & 3rd pairs, 4 review
trials were presented immediately prior to instructional trials (same consequences)
• Pre- and post-test:– 2 variables tested:
• Ability to verbally define the 12 words• Ability to read target words from photographs
– No consequence for correct & incorrect– In natural environment
Method - Procedures
• Maintenance & generalization: – Ned & Elliot: follow-up sessions 1, 3, 5, 7, & 9
weeks after the final probe session– Rita: follow-up sessions 1 and 3 weeks after
probe 4.– Probe condition procedures were used– Setting: the school library
Method - Experimental design
• Parallel treatment design
• Replication across behaviors and subjects
• Evaluates effectiveness & efficiency
Method - Reliability
• Point by point method:– One assessment per each experimental
condition and phase
From 91.6% to 100%, M 99.6%
Results 1
Results 2
Results 3
Results - summary
Results – pre-/post-test
Discussion
• Effectiveness and efficiency compared:• # of minutes of direct instruction• # of sessions to criterion• # of errors to criterion (0% - 1.4%)• Overall conclusions:
– Both 5-s CTD & 0-8-s PTD found effective– CTD more efficient than PTD (Rita’s data
obvious), although minimal
Discussion – cont’d
• History with PTD may have influenced results (facilitative effect presumed)
• 1-s increment each session rather than trial or correct response may have decreased the efficiency of PTD
• Suggestion for practice - select instructional strategies based on: effectiveness, efficiency, intrusiveness, simplicity + principle of parsimony, teacher and participant
preference, and ease of implementation.