using a modified constant prompt-delay procedure to teach spelling to students with physical...

469

JOURNAL OF APPLIED BEHAVIOR ANALYSIS 2004, 37, 469–480 NUMBER 4 (WINTER 2004)

USING A MODIFIED CONSTANT PROMPT-DELAY PROCEDURE TO TEACHSPELLING TO STUDENTS WITH PHYSICAL DISABILITIES

MARI BETH COLEMAN-MARTIN AND KATHRYN WOLFF HELLER

GEORGIA STATE UNIVERSITY

Current research suggests that constant delay is an effective means of teaching studentsthrough near-errorless learning. The current study examined how procedures used inprevious research may be modified so that constant delay can be implemented withstudents who have physical disabilities that prevent them from engaging in fluent aca-demic responding. A multiple baseline design with probes was used to assess the effec-tiveness of a modified constant-delay procedure in teaching spelling to students withphysical disabilities. This procedure was found to be effective for all 3 students.

DESCRIPTORS: constant time delay, delayed prompts, physical disabilities, spellinginstruction

Students with physical disabilities oftenfall under the category of orthopedic im-pairment. Under this category, there are stu-dents with neuromotor impairments (e.g.,cerebral palsy, spina bifida), degenerative dis-eases (e.g., muscular dystrophy, spinal mus-cular atrophy), and orthopedic and muscu-loskeletal disorders (e.g., limb deficiencies,juvenile arthritis; Bigge, Best, & Heller,2001). These students may vary widely inintellectual ability and may have additionalimpairments (e.g., visual impairments, sei-zure disorders).

Despite the wide array of differencesamong students with physical disabilities,there are several common factors that thesestudents often share that could negatively af-fect their educational performance. Thesefactors include motor limitations, restrictedmeans of communication, fatigue and en-durance limitations, health factors, experi-ential deficits, and interactional effects of ad-

This investigation was completed in partial fulfill-ment of the requirements for the PhD by the firstauthor at Georgia State University.

Correspondence concerning this article should beaddressed to Kathryn Wolff Heller, Department of Ed-ucational Psychology and Special Education, MSC6A0820, Georgia State University, 33 Gilmer StreetSE, Unit 6, Atlanta, Georgia 30303 (e-mail:[email protected]).

ditional disabilities (Heller & Swinehart-Jones, 2003). To address these issues, in-structional strategies often need to bemodified and used in conjunction with as-sistive technology.

Constant delay (also called constant timedelay; CTD) is an instructional strategy thathas been effectively used in teaching spellingskills to students with learning disabilities(Stevens & Schuster, 1987) and in combi-nation with computer-assisted instructionfor students with mild intellectual disabili-ties (Stevens, Blackhurst, & Slaton, 1991).CTD has also been used to instruct nonac-ademic tasks such as appropriate toy playand requesting skills to individuals withphysical disabilities and severe or profoundintellectual disabilities (Crawford & Schus-ter, 1993; Kratzer, Spooner, Test, & Koor-land, 1993).

Procedurally, CTD involves the deliveryof an instructional cue that is followed bythe presentation of a controlling prompt(e.g., providing an example of a correct an-swer). During the initial stages of CTD, thecontrolling prompt is presented simulta-neously with the instructional cue to teachthe student the correct response. In subse-quent sessions, the instructor gives the in-structional cue and then delays the presen-

470 MARI BETH COLEMAN-MARTIN and KATHRYN WOLFF HELLER

tation of the controlling prompt for a briefperiod so the student may respond indepen-dent of the prompt (Wolery, Ault, & Doyle,1992).

The delay interval used in CTD proce-dures typically ranges from 2 s to 5 s(Zhang, Horvat, & Gast, 1994). However,relatively short delays may preclude respond-ing in the absence of the controlling promptfor students with physical disabilities. Thatis, the delay may need to be longer when astudent has a physical disability that inter-feres with his or her ability to respond quick-ly (Wolery et al., 1992). For example, theinitial delay interval may be determined byexamining the time it takes for a studentwith a physical disability who is fluent in theskill to initiate the response and then adding2 s (Crawford & Schuster, 1993).

Due to the diversity of skills across indi-viduals with physical disabilities, the fluencyof responding may vary widely. Thus, addi-tional time intervals may be needed to pro-mote initiation and fluent task completion.A duration interval may be set for theamount of time that the individual is pro-vided to complete the target response (Wol-ery et al., 1992), with a failure to completethe task within the prespecified interval be-ing a duration error (Zhang et al., 1994).Finally, an interresponse interval may beconsidered in which a response is recordedas incorrect if the student does not respondfor a predetermined length of time.

In summary, there have been relativelyfew demonstrations of CTD procedures thathave been modified to meet the needs of stu-dents with physical disabilities (e.g., Craw-ford & Schuster, 1993; Kratzer et al., 1993),and the previous investigations have evalu-ated CTD for students with significant cog-nitive impairments. Thus, in the currentstudy we evaluated the utility of a modifiedCTD procedure to teach spelling to studentswith physical disabilities who had mild totypical levels of intellectual functioning. We

modified the CTD procedure by using sev-eral different intervals to accommodate theindividual differences associated with theparticipants’ physical disabilities. Spellingwas chosen as the target task because of itsimportance in writing and in allowing stu-dents to create novel messages on augmen-tative communication devices that can beunderstood by others (Van Daal & Van derLeij, 1992). In addition, the current studymeasured whether observational learning ofnontargeted spelling words occurred duringsmall-group instruction.

METHOD

Participants and SettingsThree students participated in this study.

All students attended a self-contained pro-gram for students with orthopedic impair-ments in a suburban elementary school andwere included in general education class-rooms for parts of the school day. All stu-dents functioned below grade level in spell-ing performance and had additional disabil-ities (e.g., visual impairments). Two of thestudents (Lexie and Autumn) had prior ex-perience with CTD for some areas of in-struction (e.g., sight-word recognition), butnot for spelling.

Lexie was a 10-year-old fourth-grade stu-dent who had spastic quadraplegic cerebralpalsy. Her speech was clear with no articu-lation errors, and she had nystagmus and avisual acuity of 20/40 for both eyes. Lexiecould read Size 14 font but typically usedSize 28 font because of visual tracking prob-lems. Although she was able to write mostsingle letters and numbers with a penciladapted with a pencil grip, she required alaptop computer with word processing soft-ware due to fatigue and illegibility of manyof her written letters. Lexie typed with herleft index finger and thumb only, and herfluency was affected by limited finger useand poor trunk stability while typing. She

471SPELLING INSTRUCTION

displayed a grade equivalence of 2:5 (secondgrade, 5th month) for spelling on theWechsler Individual Achievement Test(WIAT), and her Stanford-Binet IQ indicat-ed that she was functioning in a normalrange of intelligence.

Juana was a 10-year-old fourth-grade stu-dent who had myelomeningocele spina bi-fida and clear speech articulation. Juana hadgood motor control of her right hand; how-ever, her left hand was contracted and wasused primarily to stabilize materials. Forhandwriting, Juana used a pencil grip on herpencil and dark-line paper to help withmaintaining appropriate size and spacing ofwritten text. Her papers were secured on aclipboard on top of a slantboard with a 458angle. She had a spelling grade equivalent of2:3 on the WIAT; her IQ scores were un-available.

Autumn was a 12-year-old fifth-grade stu-dent who had spastic quadraplegic cerebralpalsy with mildly dysarthric speech. She alsohad a visual impairment that resulted in avisual acuity of 20/200. She could accuratelyidentify letters and numbers on her com-puter when the font size was 24 or higher,and she used an onscreen keyboard on a lap-top computer via a trackball for written out-put. Her fluency was relatively slow becauseshe required numerous small movements onthe trackball to move to each letter. Herspelling ability was a 1:1 grade equivalent onthe WIAT, and she was functioning in themild range of mental retardation.

Small-group instructional sessions tookplace in a classroom within the school. Ses-sions occurred with the students’ wheelchairspositioned in a semicircle, with a classroomparaprofessional standing facing the stu-dents. The teacher moved next to each stu-dent to provide individual instruction whenit was the student’s turn to spell one of hertargeted words. From this position, theteacher could see the onscreen displays of thestudent’s laptop computer or paper on the

slantboard. This seating arrangement also al-lowed the students to see large cards held upby the paraprofessional for the purpose ofobservational instruction (described below).All sessions occurred during the students’language arts time, and the target wordswere not taught at any other time during theschool day.

Preexperimental Observations

Word selection. Prior to the onset of thestudy, the students were tested on a subsetof the county’s high-frequency word list todetermine which words they were unable tospell. Testing began at the start of the listand continued until the student misspelleda total of 27 words. Students were not givenany instruction during the pretest, nor werethey told if their answers were correct. In-correct words for all students were comparedacross students, and target words for the in-vestigation were selected based on all stu-dents having spelled them incorrectly. Fromthe list of target words, each student was as-signed nine different spelling words, so thatthe target words varied across students. Au-tumn was assigned words at a lower gradelevel because her spelling ability was lowerthan the other 2 students, and the rest ofthe words were randomly assigned betweenLexie and Juana. Each student’s nine wordswere divided into three subsets of threewords (see Table 1).

Development of delay intervals. Three in-terval lengths were developed to promotefluent responding during the intervention.The initial delay interval (i.e., the initiationinterval) was determined by recording the la-tency to initiation over multiple trials. Ini-tiation was defined as the student movingher hand onto the input device (e.g., key-board) or picking up the pencil. A 5-s delayinterval was determined as an easily obtain-able time frame for all 3 students to initiatethe response. Duration intervals were deter-mined based on the amount of time that it


Table 1Target Words

Student Target wordsTrials tomastery

Lexie sinceagainthroughstoryalways

107

151022

mightthosearoundthought

10151912

Juana numberwheretogetheralmost

127

2022

whilesentenceanimalwholechildren

242725

918

Autumn newverymadeany

41403123

worklineusedownwere

2826181821

Note. Trials to mastery refers to 100% independent re-sponses for three consecutive trials, maintained throughoutthe phase.

took for the student to complete spelling theword from initiation (moving onto the inputdevice or pencil) to cessation (defined aspressing the space key after the word wasspelled or by putting the pencil down). Theaverage completion times for Lexie and Ju-ana were 28 s and 24 s, respectively, whichresulted in a 35-s interval for both partici-pants. Autumn’s average time was 53 s,which resulted in a 60-s interval. The inter-response interval was set at 10 s between theinitiation of each letter, based on Autumn’sinterresponse time for known words (i.e., 10s), which was the longest of all students.

Individual InstructionCTD procedure. Individual instruction for

the separate word sets began with the follow-ing directions delivered to the 3 students bythe teacher:

I want you to spell some words. If youare sure you know the answer, type orwrite it. If you do not know, do notguess. Wait, and I will help you so thatyou can get all of the answers right. Ifyou get 90% of the answers right, ei-ther with my help or without my help,you will get to earn a coupon which isgood for some free choice activities.

Spelling was taught using a CTD proce-dure (based on Wolery et al., 1992). DuringCTD, the controlling prompt was a com-bination of a visual prompt (an index cardcontaining the correctly spelled word typedin Size 48 font) and the teacher spelling theword aloud while pointing letter by letter. Inthe first session for each word set, instruc-tion began at a 0-s delay in which the in-structional cue (i.e., ‘‘spell [word]’’) and thecontrolling prompt were presented simulta-neously. Thereafter, delivery of the control-ling prompt was delayed until the 5-s initi-ation interval elapsed without the student at-tempting the response.

In addition to delivering the controlling

prompt after the initiation interval, the con-trolling prompt was also introduced if eitherof two other intervals elapsed without theresponse being completed. The controllingprompt was delivered if 35 s elapsed withoutthe response being completed by Lexie andJuana or if 60 s elapsed without the responsebeing completed by Autumn. Finally, thecontrolling prompt was delivered if morethan 10 s elapsed between the typing of in-dividual letters (i.e., the intertrial interval).

Individual trials were conducted in ran-dom order by placing all students’ words onindex cards in a bag; the teacher drew out acard to begin the trial. For each trial, theteacher called the student’s name, asked the


student if she was ready, and then deliveredthe instructional cue (i.e., ‘‘Spell [word]’’).Each student responded when it was herturn by handwriting the answer (for Juana)or by typing on the laptop. Each sessionconsisted of three trials for each word in thestudent’s word set, for a total of nine trialsfor each student in a session.

As in other investigations (e.g., Crawford& Schuster, 1993), descriptive praise or er-ror statements were provided throughout theCTD procedure. If the student spelled aword without the controlling prompt, theteacher gave verbal praise such as ‘‘Wow, thatis correct.’’ When the student waited for thecontrolling prompt and then had a correctresponse, the teacher said, ‘‘Good, you wait-ed correctly and got the right answer.’’ If thestudent spelled a word incorrectly, errorstatements were provided followed by teach-er delivery of the controlling prompt for cor-rect spelling. If an error occurred before thecontrolling prompt was delivered, the teach-er said, ‘‘No, that is not correct. Remember,if you don’t know, wait and I will help you.’’If an error occurred after the controllingprompt, the teacher said, ‘‘No, that is notcorrect. You must look carefully at the wordso that you spell it correctly.’’ If the studentdid not respond after given the controllingprompt, the teacher said, ‘‘You need to payattention to the word and type it on yourkeyboard (or write it on your paper).’’

In addition to descriptive praise and errorstatements, each student earned a coupon ifshe spelled 90% or more of the words cor-rectly. Three coupons could be exchangedfor an activity reinforcer (e.g., computertime, free time, trip to the library, run anerrand) of the student’s choice.

Observational Instruction

During all sessions, a classroom parapro-fessional was present in the middle of thegroup of students. While 1 student receivedindividual instruction from the teacher, the

paraprofessional presented a card containingthat student’s words in 150-point font to theother (nontargeted) students. The card wasnot presented until the target student’s trialfor a given word was completed. The non-targeted students were not required to re-spond to the larger card when it was pre-sented, and there were no consequences ifthey did respond. At the end of the inves-tigation, each student was tested on the oth-er students’ targeted words in a manner sim-ilar to the pretesting described above. Ob-servational learning was evaluated by com-paring each student’s performance on theother students’ words based on the pre- andposttest data.

Response Measurement and Reliability

The teacher served as the primary datacollector and conducted all sessions. Datawere collected on two types of correct re-sponses: independent responses and prompt-ed responses. Independent responses were de-fined as a student’s initiation of a responsewithin 5 s of the teacher’s initial request andcompletion of the spelling word within thepredetermined duration or interresponse in-tervals (i.e., correctly spelling the word be-fore the controlling prompt was delivered).Prompted responses were defined as the stu-dent correctly spelling the word after thecontrolling prompt was delivered (based onthe passage of one of the three intervals de-scribed above).

Data were also collected on incorrect re-sponses, which consisted of multiple types oferrors. Nonwaiting errors were those inwhich the student initiated the responsewithin 5 s but spelled the word incorrectly.Waiting errors were those in which the stu-dent spelled the word incorrectly followingthe delivery of the controlling prompt. In-complete-response errors occurred when the10-s initiation interval elapsed. Duration-in-terval errors occurred when the student ini-tiated the response but failed to complete


the word within the given time interval.Across each session, the number of errorswas combined to yield a measure of incor-rect responses.

Data on independent responses, prompt-ed responses, and incorrect responses wereanalyzed by dividing the number of trials inwhich each response occurred (the responseswere exclusionary) by the number of trialsin a session (i.e., nine). These data were thenmultiplied by 100% to yield the percentageof occurrence for each response.

Throughout 50% of all sessions, a secondclassroom paraprofessional collected data ontreatment integrity and on student respons-es. Treatment integrity was measured by theobserver circling a plus sign (when the teach-er followed all components of the procedurecorrectly) or a minus sign (when the teacherdid not follow at least one component of theprocedure correctly) for each trial during theentire session. For each session, the numberof pluses were divided by the sum of thenumber of pluses and minuses and multi-plied by 100% to yield an index of treat-ment integrity. Across all sessions, treatmentintegrity ranged from 98.2% to 100%, witha mean of 99.7%.

Interobserver agreement was calculatedfor each session by comparing the numberof correct and incorrect student responsesthat were recorded separately by the teacherand the paraprofessional on a trial-by-trialbasis. An agreement was defined as the twoobservers recording the same number of in-dependent, prompted, and incorrect re-sponses in a given trial. A disagreement oc-curred if the number of independent,prompted, and incorrect responses differed(for any type of response) in a trial. Thenumber of agreements for independent,prompted, and incorrect responses in a trialwas divided by the number of agreementsplus disagreements in that trial and wassummed across all trials for each session.The resulting quotient was multiplied by

100%. During all sessions, agreement was100% for independent, prompted, and in-correct responses.

Experimental Conditions

Baseline probes. The purpose of the base-line probes was to evaluate spelling beforeand after individual instruction with theCTD procedure. Probes were important todemonstrate the functional relation betweenspelling and the CTD procedure in that thestudents should correctly spell only thosewords on which they had received prior in-struction. Other than the instructional cue(i.e., ‘‘Spell [word]’’), no prompts, differen-tial feedback, or programmed reinforcerswere provided during the baseline probes.

At the beginning of the study, three probesessions were conducted for each word set toestablish baseline levels of independent re-sponding (data for the first probe sessionwere taken from the pretest word assess-ment). Once mastery criterion was reachedwith the first word set during instructionwith the CTD procedure, probe sessionswere conducted again to assess responsemaintenance in the absence of any pro-grammed instruction for the word set.Throughout the analysis, probe data werecollected on all word sets to assess acquisi-tion of untaught words prior to and afterinstruction and to assess maintenance of re-sponding for previously taught word sets. Intotal, the probe condition was conductedfour times with each word set.

Once the CTD procedure and subsequentbaseline probes had been conducted acrossall word sets, a final probe session was con-ducted for all participants after the investi-gation was completed. The follow-up probewas conducted 23 days after the study forLexie, 11 days for Juana, and 10 days forAutumn.

Instruction with CTD. The CTD proce-dure was sequentially introduced across thethree word sets using a multiple baseline de-


Figure 1. Percentage of words spelled correctly by Lexie during probe and instruction with CTD phases.The line break between Sessions 21 and 22 represents the week of spring break.

sign. After the conclusion of the first probephase, the intervention was randomly imple-mented with one word set and the students’did not receive intervention for the othertwo word sets. Criterion for mastery was metwhen the student had 100% independentresponses for the targeted word set on threeconsecutive sessions. Thereafter, probe datawere collected on all word sets, and theCTD procedure was subsequently intro-duced across the second word set. After thesubsequent probe sessions, the CTD proce-dure was introduced for the final word set.

RESULTS

Lexie

The data on independent and promptedresponses for Lexie are shown in Figure 1.For Word Set 1, introduction of the CTDprocedure resulted in a gradual increase inindependent responses that was associatedwith a decrease in prompted responses. Lexiereached mastery criterion on the first wordset after seven sessions with the CTD pro-cedure in effect. Independent responding forWord Set 1 was maintained during the sub-


Figure 2. Percentage of words spelled correctly by Juana during probe and instruction with CTD phases.The line break between Sessions 18 and 19 represents the week of spring break.

sequent probe trials. A similar effect follow-ing introduction of the CTD procedure wasobserved for Word Set 2 and Word Set 3.Lexie reached mastery criterion after 10 and9 sessions for Word Sets 2 and 3, respec-tively. Independent responding was main-tained in the probe that was conducted 23days later. Across all word sets, incorrect re-sponses covaried with the occurrence of in-dependent and prompted responses. Incor-

rect responses averaged 2.4%, 1.1%, and3.7% across Word Sets 1, 2, and 3, respec-tively (data not shown).

Juana

Juana’s data are shown in Figure 2. Noindependent responses were observed duringthe initial baseline probes. When the CTDprocedure was introduced for the first set ofwords, we observed an increase in indepen-


Figure 3. Percentage of words spelled correctly by Autumn during probe and instruction with CTD phases.The line break between Sessions 19 and 20 represents the week of spring break.

dent responses and a decrease in promptedresponses. Similar patterns of respondingwere observed for the remaining two sets ofwords, with greater variability observed inWord Set 2. Juana reached mastery criterionfor the word sets as follows: Word Set 1, 9sessions; Word Set 2, 12 sessions; Word Set3, 11 sessions. In the probe conducted 11days after the completion of the study, Ju-ana’s independent responding was main-tained at 100% across all three word sets.

Across Word Sets 1, 2, and 3, incorrect re-sponses averaged 2.4%, 3.8%, and 7.0%, re-spectively (data not shown).

Autumn

Figure 3 depicts the outcome of the CTDintervention for Autumn. After no correctresponding occurred in baseline, implemen-tation of CTD produced an increase in cor-rect responding for both prompted and in-dependent responses. After some variability,


Autumn ultimately began to respond with-out the help of the controlling prompt acrossall three word sets. Autumn reached masterycriterion for the word sets as follows: WordSet 1, 16 sessions; Word Set 2, 12 sessions;Word Set 3, 9 sessions. Independent re-sponding was maintained during the probeconducted 10 days after the completion ofthe study. Incorrect responses averaged13.8%, 4.6%, and 6.1% across Word Sets1, 2, and 3, respectively (data not shown).

Observational Instruction

Results of the observational learningprobes were mixed across participants. Asmentioned before, all target words werethose that all 3 students did not spell duringthe pretest. Posttest data showed that Lexieand Juana learned to spell the words of theother students (data not shown). Lexielearned 83% of Autumn’s words and 56%of Juana’s words. Juana learned 100% of Au-tumn’s words and 33% of Lexie’s words. Bycontrast, Autumn did not accurately spellany of the other students’ words, but shemade closer approximations (e.g., Autumnspelled the word around as ‘‘xc’’ during thepretesting and ‘‘orad’’ during posttesting;data not shown).

DISCUSSION

The purpose of this investigation was toevaluate the utility of a modified CTD pro-cedure for teaching spelling words to stu-dents with physical disabilities. For all 3 stu-dents, correct responding on the target wordsets did not increase until the CTD proce-dure was introduced. Furthermore, all 3 stu-dents were able to maintain accuracy acrossprobe conditions in which the interventionwas no longer in place.

To accommodate the students’ physicalneeds in this study, a 5-s delay was used forinitial motor movement to the writing de-vice, a duration time limit for completion of

each word was set, and an intertrial intervalwas used to facilitate paced responding.These intervals were individually determinedbased on observations of the students’ per-formance during pretesting. Setting multipledelays based on individual criteria is a rela-tively novel procedure for CTD, and the re-sults of the current investigation suggest thatfuture researchers and practitioners shouldconsider using naturalistic observations toset delay intervals for students with physicaldisabilities (Crawford & Schuster, 1993). Itshould be noted, however, that only one ofthe three intervals (i.e., the duration inter-val) was individualized for the participants.All other intervals were identical across par-ticipants.

Although all students acquired the targetwords using the modified CTD procedure,it is unclear whether the procedures used inthe current investigation are more effectivethan more commonly used CTD procedures(e.g., Wolery et al., 1992). Thus, the relativecontributions of the individual componentsof the modified CTD procedure remain un-known. Nevertheless, these preliminary datasuggest that a modified CTD procedure iseffective for teaching academic skills to chil-dren with physical disabilities. Future re-search could conduct within-subject evalua-tions of CTD procedures that are and arenot modified to meet the idiosyncratic needsof each student.

In addition to the evaluation of CTD, wealso conducted a pretest–posttest analysis ofwhether observing the words being taught toanother student was sufficient to produce ac-quisition. Although the pretest–posttest de-sign used for observational learning data wasnot adequate to demonstrate a functional re-lation, the data indicated that all 3 studentswere able to benefit by being exposed to theother students’ words. These data suggestthat simply repeating the presentation ofnontargeted words may be sufficient forsome acquisition. Further research is needed


to more closely examine observational learn-ing effects. In addition, performance duringobservational instruction may have been in-fluenced by the students’ history of directreinforcement for spelling (Bandura, 1975).Finally, Lexie and Juana were able to learnhigh percentages of Autumn’s words (83%and 100%, respectively), possibly becauseher words were at a lower grade level. Bycontrast, Lexie and Juana had more difficultylearning each other’s words (56% and 33%,respectively), and Autumn demonstrated in-creased approximations only, further sug-gesting that acquisition of novel responsesmay be influenced by response difficulty.

Although all students showed an increasein independent responding following the in-tervention, it is unclear what operativemechanism accounted for response acquisi-tion. That is, the intervention used in thecurrent investigation consisted of multiplecomponents. In addition to the basic pro-cedures of CTD (i.e., instructional cuing,controlling prompt), the students also re-ceived differential feedback for correct andincorrect responses and coupons as a tokeneconomy system. It is possible that thesecomponents, individually or in combination,may have contributed to the results. Futureinvestigations should examine the individualcontribution of each component of suchprograms to determine which componentsare related to an increase in correct respond-ing.

Despite the results obtained, the outcomeof this investigation is limited by the mannerin which the intervention was introducedwithin the multiple baseline. That is, whenthe intervention was introduced with oneword set, data collection did not occur withthe other two data sets until the subsequentprobe sessions. Thus, we did not directly testthe prediction that behavior change wouldoccur only in the baseline that received in-tervention because we could not compare re-sponding at the same points in time (Kaz-

din, 1982). However, probe sessions wereconducted at the same point in time for allword sets, and these data indicate that ac-quisition occurred for a given word set onlyafter the intervention had been implement-ed.

In conclusion, this study supports the useof a CTD procedure as an effective instruc-tional strategy for teaching spelling words tostudents with physical disabilities. These re-sults also extend the current literature on theapplication and modification of CTD pro-cedures for instructing students with physi-cal disabilities. When using CTD with stu-dents who have physical disabilities, consid-eration should be given to setting delays thataccommodate slower motor movements andto the use of assistive technology devices(e.g., an onscreen keyboard) that might assistwith performance.

REFERENCESBandura, A. (1975). Analysis of modeling processes.

School Psychology Digest, 4, 4–10.Bigge, J. L., Best, S. J., & Heller, K. W. (2001).

Teaching individuals with physical, health, or mul-tiple disabilities (4th ed.). Upper Saddle River, NJ:Prentice Hall.

Crawford, M. R., & Schuster, J. W. (1993). Usingmicroswitches to teach toy use. Journal of Devel-opmental and Physical Disabilities, 5, 349–367.

Heller, K. W., & Swinehart-Jones, D. (2003). Sup-porting the educational needs of students with or-thopedic impairments. Physical Disabilities: Edu-cation and Related Services, 22, 3–24.

Kazdin, A. E. (1982). Single-case research designs:Methods for clinical and applied settings. New York:Oxford University.

Kratzer, D. A., Spooner, F., Test, D. W., & Koorland,M. A. (1993). Extending the application of con-stant time delay: Teaching a requesting skill tostudents with severe multiple disabilities. Educa-tion and Treatment of Children, 16, 235–253.

Stevens, K. B., Blackhurst, A. E., & Slaton, D. B.(1991). Teaching memorized spelling with a mi-crocomputer: Time delay and computer-assistedinstruction. Journal of Applied Behavior Analysis,24, 153–160.

Stevens, K. B., & Schuster, J. W. (1987). Effects ofa constant time delay procedure on the writtenspelling performance of a learning disabled stu-dent. Learning Disabilities Quarterly, 10, 9–16.


Van Daal, V. H. P., & Van der Leij, A. (1992). Com-puter-based reading and spelling practice for chil-dren with learning disabilities. Journal of LearningDisabilities, 25(3), 186–195.

Wolery, M., Ault, M. J., & Doyle, P. M. (1992).Constant time delay procedure. In N. Silverman(Ed.), Teaching students with moderate to severe dis-abilities (pp. 47–71). White Plains, NY: Long-man.

Zhang, B. L., Horvat, M., & Gast, D. L. (1994).Using the constant time delay procedure to teachtask-analyzed gross motor skills to individualswith severe intellectual disabilities. Adapted Phys-ical Activity Quarterly, 11, 347–358.

Received June 3, 2003Final acceptance August 16, 2004Action Editor, Henry Roane

STUDY QUESTIONS

1. Briefly describe the general characteristics of the constant prompt-delay procedure.

2. What were the three types of delay intervals used to promote fluent responding, and howwas each interval selected?

3. What controlling prompt was used during the constant prompt-delay procedure, and underwhat conditions was it implemented?

4. What was the difference between an independent and a prompted response?

5. What types of errors were scored as incorrect responses?

6. Summarize the results of this study.

7. What feature of Autumn’s data suggested that exposure to words per se may have influencedspelling performance?

8. Why might it be useful to evaluate the separate components of the constant prompt-delayprocedure used in the current study, and how would such an evaluation be conducted?

Questions prepared by Jennifer Hammond and David Wilson, University of Florida

using a modified constant prompt-delay procedure to teach spelling to students with physical...

Documents