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.