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The Task Demonstration Model: a concurrent model for teaching groups of students with severe disabilities.

Significant progress has been made in the past 10 years in implementing functional, community-based educational programs for people with severe mental retardation. However, there are many questions about the best procedures for teaching these students in their classrooms. The challenge is to identify teaching strategies that are both effective for students and practical for staff.

One of the more frequent debates has been whether these students should be taught individually or in groups (Reid & Favell, 1984). Traditionally, students with severe disabilities have been taught in one-to-one situations. Because of the finite amount of teacher time available, however, this approach has meant that students received relatively small amounts of instruction per day. Indeed, in observations of 30 classrooms, we have found direct instruction to occur less than 10% of the school day.

Group instruction involving a small number of students may significantly increase instructional time for each student. Several investigators have compared one-to-one teaching with group instruction and found no deficit in skill acquisition when students were taught in groups (Bourland, Jablonski, & Lockhart, 1988; Favell, Favell, & McGimsey, 1978; Fink & Sandall, 1980; Storm & Willis, 1978). Moreover, group instruction has been found to be superior in efficient use of teacher time (Favell et al., 1978; Fink & Sandall, 1980), opportunities for social contact (Storm & Willis, 1978), incidental learning (Biberdorf & Pear, 1977), and decreased rates of inappropriate behavior (Ranieri, Ford, Vincent, & Brown, 1984).

Although there are many advantages to group instruction, some concerns remain regarding its use. These include the difficulty of training students with heterogeneous skills (Westling, Ferrell, & Swenson, 1982), the type and difficulty of tasks appropriate for group instruction (Alberto, Jobes, Sizemore, & Duran, 1980; Favell et al., 1978), the decreased opportunities for individual students to respond during group instruction (Bourland et al., 1988), the question of whether the students should be taught the same or different tasks (Oliver 1983), and the selection of an appropriate group instruction model (Storm & Willis, 1978).

With respect to the latter, Reid and Favell (1984) have identified three general models of group instruction. In the sequential model, each student is taught individually in a sequential order while the other students in the group wait for their instructions. This is the most common alternative for persons with severe or moderate retardation, but it is in effect a series of one-to-one teaching situations. In the combination con-current/sequential model, some instruction is provided to all the students concurrently while other instruction is provided to individual students in sequential order. In the third model, the tandem individual-to-group model, the instruction begins with a one-to-one format and is systematically extended to include more students.

For each of these models, there is considerable time during group instruction in which the nontarget student does not have an opportunity to respond. The teacher may be requesting a response from another student, prompting another student's response, or correcting errors. During these periods, the nontarget student may decrease contact with the learning environment and increase problem behavior (Repp & Karsh, 1991; Repp and Karsh, in press). Since the major problem of students with severe disabilities is, by definition, that they take longer to learn tasks, unnecessary periods without instruction would seem counterproductive.

One group instruction model that has not been investigated with these students is a concurrent model in which all the students in the group respond concurrently on the same tasks throughout the teaching session. An advantage of a concurrent model is that each student receives many more opportunities to respond than in the previous models. In addition, there are the added benefits of socialization for the students and time management for the teacher. The implication inherent in this model, however, is that each student must exhibit a high rate of correct responding in order for all in the group to respond concurrently as the task progresses. Because students with severe disabilities are usually quite diverse in their skill levels, implementing a concurrent group instruction procedure can be problematic. The key to the success of such a model may be the incorporation of teaching procedures that result in few errors.

The purpose of this investigation was to determine whether a teaching procedure (the Task Demonstration Model) which had resulted in high rates of correct responding and few errors in one-to-one instruction (Karsh, Repp, & Lenz, 1990; Repp, Karsh, & Lenz, 1990) could be used effectively in a concurrent group instruction model. The critical features of the Task Demonstration Model (TDM) are fading (Terrace, 1963a, 1963b), general case programming (Horner, Bellamy, & Colvin, 1984), and a hierarchy of skills from matching to sample to identification to naming. In the present study, classroom teachers received training not only in the Task Demonstration Model but also in the characteristics of effective instruction based on recent stimulus control research. Teachers were trained to maintain a rapid pace of instruction, to use a signal for unison responding (Cowart, Carnine, & Becker, 1976), to present multiple examples of the stimuli to be learned, and to differentially reinforce correct responding. The research purpose was addressed by comparing TDM with a more traditional method of group instruction, the Standard Prompting Hierarchy (SPH), which used a system of least-to-most intrusive prompts. Comparisons were made on (a) the students' percentage of correct responses, rate of correct responses, and task engagement; and (b) the teachers' rate of demands, praise, and prompts.



Students. Three groups of students, ranging from 16 to 21 years of age, participated in the study. All three groups were part of a functional, community-based training program for students with severe to moderate disabilities in a school located in a large suburban area.

Group 1 included 2 males and 2 females whose mean chronological age was 20 years, 2 months (range, 19 years, 7 months to 20 years, 4 months). The mean score on the Stanford-Binet Intelligence Scale-Revised was 35 (range, 32-36). Group 2 was composed of 1 male and 3 female students. The mean chronological age was 19 years, 6 months (range, 19 years, 10 months to 21 years), and the mean score on the Stanford-Binet was 38 (range, 30-49). Group 3 included 1 male and 2 female students. The mean chronological age was 17 years, 8 months (range, 16 years, 7 months to 18 years, 8 months), and the mean score on the Stanford-Binet was 40 (range, 30-45).

All the students were able to attend to a task and remain seated for 20 min. Each student was able to respond to commands such as "Look at --" and "Touch the --" as the result of a program used to train compliance (Repp & Karsh, 1991). None of the students possessed significant sensory or motor disabilities that could interfere with the responses required during instruction.

Teachers. Three teachers participated in the study. All were certified to teach students with severe and moderate retardation and had taught this population for an average of 13 years (range, 10-15 years). Teachers 1 and 2 had earned master's degrees, and Teacher 3 had earned a baccalaureate degree with additional graduate hours in special education.


Observations took place in the students' home-room classrooms, where functional academic tasks were taught in preparation for community activities. Classroom and community activities were alternated during the week so that students received classroom instruction an average of twice a week. In each classroom, group instruction was conducted at a kidney-shaped table with the teacher facing the students.

Experimental Design and Conditions

The study used a multiple baseline design (Baer, Wolf, & Risley, 1968) across the three teacher/student groups with an embedded alternating-treatments phase (Barlow & Hayes, 1979; Barlow & Hersen, 1984) for comparing the effectiveness of the two group teaching procedures.

Baseline. After an initial period of adjustment to allow students and teachers to become accustomed to the observers, probe sessions were randomly conducted for 5, 6, and 7 of the baseline teaching days for Groups 1, 2, and 3, respectively. Teachers were asked to instruct the target group of students as they normally would. They were not aware of the specific nature of the observations. The primary and reliability observers were seated behind the students. All other activities that were a regular part of the classroom routine were continued.

Following baseline, the three teachers participated in three workshops conducted by the experimenters. The purposes of the workshops were (a) to describe teaching procedures, based on recent stimulus control research, that had resulted in more effective instruction for students with severe and moderate disabilities (see Table 1); (b) to demonstrate how these procedures could be integrated into group instruction in the classroom; and (c) to train teachers to use the TDM, which had been shown to be effective in teaching functional discriminations during one-to-one instruction (Karsh et al., 1990; Repp et al., 1990). After the workshops were conducted, the teachers were observed with target students twice a week for 5 weeks and given feedback on their use of the stimulus control instructional procedures with both the TDM and the SPH. This training period ended when the teachers had demonstrated 100% procedural reliability for three consecutive teaching sessions for both TDM and SPH.

Alternating Treatment Conditions. Three probe sessions were conducted randomly for both TDM and SPH during the intervention phase. Each group of students was taught six tasks; three tasks were randomly assigned to the TDM, and three to the SPH. All six tasks were part of a single ongoing curricular activity (e.g., shopping), similar in type and difficulty, and not known by the students, according to baseline probes. The items were judged to be of equal difficulty by a panel of three other teachers. Group 1 was taught to match to a sample and to identify six department signs for shopping at stores such as K-Mart (e.g., "Service," "Cosmetics," "Pharmacy," "Records," "Sportswear," and "Jewelry"). Group 2 was taught to match to a sample and to identify six minute-hand positions for reading analog clock times (e.g., o'clock, :15, :20, :30, :45, and :50) that were part of the student's daily schedule, and Group 3 was taught to match to a sample and to identify six words related to mobility in the community (e.g., "Enter," "Exit," "Men," "Women," "Open," and "Closed"). All words or times selected came from the activity analysis (see Table 1) used to determine elements of community environments students should be able to identify to participate in the activity. Preintervention probes, which included 10 two-choice trials for each task for both matching to sample and identification, were administered individually to each student. These probes established that none of the students had mastered matching to sample or identification of the teaching stimuli before intervention. When all students in a group scored less than 60% on the matching to sample and identification probes for a given task, it was assigned to their group. During intervention, TDM, rather than SPH, was chosen as the first session for two of the three groups. This was an effort to control for the students' previous long-term exposure to a least-to-most prompting hierarchy taught in a one-to-one manner. Because the TDM condition was the first time these students had been taught in a group, we presumed its effects might suffer and that the data, therefore, would not be prejudiced in its favor. [TABULAR DATA OMITTED]

Task Demonstration Model. The Task Demonstration Model (Karsh et al., 1990; Repp & Karsh, 1991; Repp & Karsh, in press; Repp et al., 1990) is a teaching procedure that incorporates elements of fading (Sidman & Stoddard, 1966, 1967; Terrace, 1963a, 1963b), general case programming (Horner, Bellamy, & Colvin, 1984), and a hierarchy of skills in which people learn to match to a sample before learning to identify a stimulus without a sample present. During both the matching-to-sample and identification phases of instruction, students were presented with correct (S+) and incorrect (S-) stimuli with the S-(i.e., the incorrect word or clock face) faded to become more like the S+ over trials. In addition, the irrelevant features of the S+ and S- examples varied across trials. This procedure reduced the probability that the student would respond to an irrelevant dimension (e.g., color, size) instead of the relevant dimension (i.e., shape of letters or position of clock hands).

Students were taught in a hierarchy that required them to match the S+ to a sample S+ before they were taught to identify the S+. In both matching to sample (MTS) and identification (ID), stimuli were presented in three hierarchical groups. These groups were roughly defined by the degree to which S- differed from S+: (a) very different S-'s, (b) moderately different S-'s, and (c) slightly different S-'s. This systematic progression from very different to moderately different to slightly different examples provided both a reduction in errors and exposure to many examples of the S+ and S- so that the student could not learn to associate the same irrelevant aspect of S+ with reinforcement across trials.

During group instruction trials, depending on whether the students were in the MTS or ID phase, each student was presented with either (a) a sample S+, a matching S+, and an S- (in MTS); or (b) an S+ and S- (in ID). The teacher gave a direction (e.g., "Everybody, touch [underscore]"), paused 1 s, and then auditorily signaled (e.g., a hand clap) the students to respond. Students then made a unison response to the instruction. For any given trial, each student in the group had a different example of S+ and S-. After a trial was completed, students passed the stimulus materials to their left so that no one ever had the same materials across successive trials.

Incorrect responses were followed by an error-correction procedure (Karsh et al., 1990; Repp et al., 1990) during which the remaining students observed the procedure. When a student made an error, the teacher (a) physically guided the student's hand to the correct stimulus and said "No, this is [underscore]," and repeated the trial, leaving the stimuli in place; (b) then removed the stimuli, returned them to their original positions on the table, and repeated the trial; and (c) removed the stimuli, returned them to the table in different positions, and repeated the trial. For each group of S-'s (i.e., very different, moderately different, and slightly different), each student was required to make 9 out of 10 correct responses before the group proceeded to the next step (i.e., from very different to moderately different to slightly different S-'s).

For each task taught through TDM, there were two sets of training stimuli constructed from index cards (5 x 7 in). One set represented the S+ stimuli, and one represented the S-. The S+ was always presented in its criterion form, but the irrelevant dimensions varied across the multiple examples. In the tasks requiring word identification, the following irrelevant dimensions were varied: letter style, letter size, color of letters, and color of the background card. In the tasks requiring time-telling, the following irrelevant dimensions were varied: the size and color of the clock face; the size, color, and script of the numerals; and the width and design of the hour and minute hands.

For the word identification tasks, the S-'s were words found in stores that were inventoried for this purpose. The S-'s were either functionally or structurally similar to the S+ and were put into the three categories (very different S-'s, moderately different S-'s, and slightly different S-'s) of 10-15 words each. For the time-telling task, the S-'s were analog clock times similar to the S+ and were put into the three categories according to how much the hour and minute hands of the S- differed from that of the S+.

The teachers were asked to follow the implementation steps for TDM that were outlined during training (i.e., teaching MTS before ID and programming from very different to moderately different to slightly different S-'s). During the TDM sessions, the teachers were asked to incorporate the stimulus control procedures they had learned during the workshops. The teachers were particularly encouraged to maintain a rapid pace of instruction, to use a signal for unison responding, and to praise correct responses.

Standard Prompting Hierarchy. The Standard Prompting Hierarchy is a traditional procedure for teaching identification (Steege, Wacker, & McMahon, 1987; Wolery & Gast, 1984). This procedure used a hierarchy of prompts in combination with a trial-and-error (i.e., no fading) approach to teach matching to sample and identification of the S+. During group instruction with SPH, the teacher used flashcards, picture cards (representing the words or time of day), and worksheets. Students were asked to respond to instructions such as "Touch [underscore]," "Show me the word that goes with this picture," "Draw a circle around [underscore]," and so forth. Students did not pass the materials as in TDM; instead, each student used the same materials throughout the session.

If the student made an error or did not respond within 10 s, a least-to-most prompting hierarchy was used in the following sequence: (a) repeated instruction, (b) instruction plus pointing to the S+, (c) instruction plus modeling (the teacher touched the S+), (d) instruction plus physical prompt (the teacher touched the back of the student's hand), and finally, (e) instruction plus full physical guidance. The students were required to make 9 out of 10 correct responses on matching to sample before proceeding to identification on each task.

There were also two sets of SPH stimuli, one for S+ and one for S-. Because this procedure did not involve fading or multiple examples, the S+ and S- stimuli did not vary as in TDM. For each task taught by SPH, two examples of the S+ were used, a flashcard (a word or clock face drawn with a black marker on a white card) and an 8-1/2- x 11-in teacher-made worksheet (a word or clockface drawn with pen on white paper and duplicated on a copy machine). No more than four examples of S- were presented on individual flashcards, and no more than four examples of S- were presented on the worksheet. The teachers were asked to adhere to the prompting hierarchy, moving from least intrusive (pointing) to most intrusive (physical guidance) when prompting student responses.

Teachers were asked to follow the steps for SPH that were outlined during training. As in the TDM implementation, the teachers were asked to incorporate the stimulus control procedures they had learned during the workshops and practiced in their classrooms. They were trained to maintain a rapid pace of instruction, to use a signal for unison responding, and to differentially reinforce correct responding.

Observational Procedures

Each teacher and group of students were observed during the three instructional conditions (baseline, TDM, and SPH), and data were collected on both teacher and student behaviors.

Response Definitions. Data were collected on three teacher and four student behaviors, defined as follows:

1. Teacher demand: Any verbal or gestural behavior that required an immediate task-related response from the student. Demands included questions; directions to manipulate instructional materials; or requests to make verbal, written, gestural, or physical responses.

2. Teacher prompt: Any verbal, gestural, or physical behavior that assisted the student in making an immediate task-related response. Such behaviors included verbal cues, visual cues, modeling, and physical guidance.

3. Teacher praise: Any verbal statement, gesture, or touch that indicated the student responded correctly.

4. Student correct response: An unprompted correct response that occurred within 10 s of the teacher's instruction.

5. Student incorrect response: An incorrect response or failure to make a response within 10 s of the teacher's instruction.

6. Student prompted response: Any correct response to the targeted instructional task that was preceded by verbal or visual cues, modeling, or physical guidance.

7. Student engagement: Any active or passive response that suggested attention to instruction. Active responses included verbal, gestural, or written responses according to teacher questions, or manipulation of the instructional materials. Passive responses included looking at the teacher, looking at the materials, or observing another student making a task-related response.

Data Collection. Data were not collected every day because the students received classroom instruction an average of twice a week on a schedule that varied from week to week. Therefore, an observation schedule was developed before the intervention phase, and probe sessions were randomly assigned to each condition. A sequential recording system (Thomson, Holmberg, & Baer, 1974) was used for both teacher and student behaviors. The teacher was observed throughout the whole session, but each minute a different student was observed. The average teaching session was 25 min (range, 21-35 min); thus, each of the four students was observed 5 to 8 times within a given session. The order of the sequential observations was randomly determined and changed for each teaching session.

The Epson HX-20, a portable microcomputer that had been programmed to collect data in real time (Repp, Harman, Felce, Van Acker, & Karsh, 1989; Repp, Karsh, Van Acker, Felce, & Harman, 1989), was used for recording the response codes. Before each session began, the observer entered a code to identify the teacher, the student, group, location, instructional task, and session. The observer then began the session by depressing a key that activated the computer's timer, as well as its recording mode. The computer was programmed to signal the observer to move from one student to another each minute, and the data for these 1-min subsessions were stored separately. During the session, each subject and each response code was allocated a key on the computer keyboard. During the 1-min subsessions, the observer depressed the appropriate key once for the onset of each teacher or student response code and a second time for its offset. The computer stored the response codes in the order of occurrence as well as the beginning and ending times in seconds. The computer was programmed to accept multiple entries so that responses occurring in combination with each other (e.g., engagement and correct responses) could be recorded simultaneously.

At the end of each session, the computer printed the sequence in which each 1-min observation session and each response code occurred, as well as the beginning and ending second for each code. In addition, it aggregated all the 1-min samples for each student. A data analysis program (Karsh, Repp, & Ludewig, 1989) was then used to calculate and print the following data for the teacher and each student: (a) the number of occurrences of each response code, (b) the rate of occurrence for each code, (c) the total duration of each code, and (d) the percentage of the session each code occurred. For each of these measures, the group data for each session were derived by calculating the mean of the individual student's data.

Interobserver Agreement

Observers were trained in vivo in classrooms until they reached a mean agreement level of 80% on each response code. Reliability checks were conducted during 33% of the sessions.

Interobserver agreement was computed for the start and finish times for each response category for the teachers and students. The method used for estimating reliability of real-time data has been described elsewhere (MacLean, Tapp, & Johnson, 1985; Repp, Harman, et al., 1989; Repp, Karsh, et al., 1989). Interobserver agreement means and ranges for each category were: (a) teacher demand: M = 95%, range = 83%-100%; (b) teacher prompt: M = 93%, range = 80%-100%; (c) teacher praise: M = 94%, range = 83%-100%; (d) student correct response: M = 96%, range = 91%-100%; (e) student incorrect response: M = 86%, range = 77%-100%; (f) student prompted response: M = 93%, range = 75%-100%; and (g) student engagement: M = 92%, range = 80%-100%.

Interobserver agreement on the independent variable was assessed in a different manner. Each day, another observer wrote a description of the stimulus materials used for TDM and SPH, the prompting hierarchy for SPH, and whether the teacher was using matching to sample or identification. This information was also recorded by the senior author. A comparison of these data showed a reliability score of 100% for the use of the two independent variables, TDM and SPH.


The results of the two teaching procedures for mean student task engagement, mean percent unprompted correct responses, and mean rate of unprompted correct response by group are shown in Figures 1, 2, and 3, respectively. Each data point represents mean responding on a new task during instruction. Figure 1 shows that engagement was similar across the baseline, TDM, and SPH conditions for the subjects within Group 1 (Ms = 76%, 72%, and 79%), Group 2 (Ms = 81%, 80%, and 84%), and Group 3 (Ms = 74%, 88%, and 76%).

Figure 2 shows that the mean percent of unprompted correct responses improved substantially from baseline (M = 47%) for both the TDM (M = 92%) and SPH (M = 82%) conditions, although responding was 10% higher in TDM than in SPH. Group 1's correct responding improved from 47% in baseline to 94% (TDM) and 90% (SPH) during intervention. Group 2 improved from 55% (baseline) to 86% (TDM) and 71% (SPH), and Group 3 improved from 40% (baseline) to 96% (TDM) and 83% (SPH). The results for individual students in Table 2 suggest that for Groups 2 and 3, SPH produced more variability within a group than did TDM.

The mean rate of unprompted correct responses per minute (rpm), shown in Figure 3, showed substantial differences between TDM and SPH. Though both procedures resulted in higher rates than in baseline, the rate of unprompted correct responses in TDM was twice that in SPH for all three groups. The means for this measure under baseline, TDM, and SPH were 0.26, 1.93, and 0.90 rpm for Group 1; 0.39, 1.50, and 0.74 rpm for Group 2; and 0.39, 3.45, and 1.70 rpm for Group 3. The rates for the students in Group 2 were lower than those in the other two groups because these students' activity level during all educational activities was considerably lower. Individual data, presented in Table 2, show that TDM produced almost equal rates of correct responding for all students within each particular group, whereas SPH led to considerable variability for students within each group.

The results for teacher demands, praise, and prompts are presented in Figures 4, 5, and 6, respectively. All three teachers increased their rates of demands or instructions over baseline with no consistent differences between TDM and SPH (Figure 4). Similarly, teacher praise increased from baseline conditions for all three teachers and was roughly the same for TDM and SPH (Figure 5).

Data on prompts (Figure 6) show them to have been two to three times as frequent in SPH as in baseline for two of the three teachers. In TDM, the rates decreased significantly from baseline. Since prompts are a function of errors, these data are consistent with the differences in rate of correct responses found under the two conditions. The rates of prompts for baseline, TDM, and SPH for the three groups were 0.48, 0, and 1.66 rpm (Group 1); 1.22, 0.38, and 2.7 rpm (Group 2); and 1.41, 0.07, and 1.45 rpm (Group 3).


Prior research has shown that TDM could be much more effective than SPH in one-to-one teaching situations (Karsh et al., 1990; Repp et al., 1990). The present results demonstrate that the effectiveness of the TDM is not restricted to one-to-one instruction; instead, they show that TDM can also be more effective in a concurrent model of group instruction. This finding is important for teaching students with severe disabilities because they often require many trials to learn a task. TDM allowed the teacher to provide an equally high number of trials to all of the students during group instruction and to facilitate relatively rapid acquisition of skills with few errors. The procedure also allowed the teacher to monitor, reinforce, and correct students and maintain a rapid pace because (a) students were attending better in TDM than in baseline, (b) reinforcement [TABULAR DATA OMITTED]

was given while the students were passing the materials, (c) error corrections were less frequently needed than during baseline, and (d) the error correction procedure was used simultaneously with the students who made errors on any given trial.

Data were collected on two sets of variables, one for students and one for teachers. The student data show, for both TDM and SPH, a substantial improvement in the students' percentage and rate of unprompted correct responding. These results validate the effectiveness of the teacher training program. In comparing TDM with SPH, one finds that while the data on percentage unprompted correct favored TDM slightly (by 10%), the data on rate unprompted correct favored TDM considerably (2 times the rate). TDM greatly increased a student's rate of contact with the learning environment, an objective we believe is essential in teaching students with severe disabilities. This effect is particularly evident when baseline and TDM are compared, showing an improvement by a factor of 6.5 (0.35 rpm vs. 2.29 rpm). The consistency of the relative relationship of the data is also interesting. Although the rate differed across the three groups, as one would expect, the TDM rate for each group was almost exactly twice the SPH rate. These data also suggest that rate is a far more sensitive measure of the differences between some teaching procedures than is the percentage correct.

The student data on task engagement are also informative. Engagement is a variable that has been used to measure the effectiveness of instruction in classrooms for students with severe disabilities (e.g., Green, Canipe, Way, & Reid, 1986; Green, Reid, McCarn, Schepis, Phillips, & Parsons, 1986). Our data on engagement show few differences among baseline, TDM, and SPH; the rate correct data, however, show considerable differences. If engagement had been selected as the only measure by which the three conditions were compared, one might have drawn the conclusion that there were no differences among the three conditions. Our suggestion is that although task engagement can be a valuable measure, additional variables should be measured to determine the effectiveness of classroom instruction.

The second set of data, on teacher behaviors, also provides interesting results. Teacher demands and praise showed significant increases over baseline conditions, although no differences were found between TDM and SPH. These changes from baseline indicate that the teacher training program led to significant changes in teacher behavior and serve to validate the program for training in both TDM and SPH procedures. The data also suggest that these teacher-demand-and-praise behaviors cannot account for the differences between TDM and SPH in the student data. Our conclusion is that the differences may be due to variables of the TDM package other than rate of demand and praise.

One of these variables may be teacher prompts. The rate in SPH (1.94 rpm) was more than 12 times the rate in TDM (0.15 rpm). This difference in rate of teacher prompts is important for two reasons. Learning research has indicated that an extra-stimulus prompt by the teacher may "overshadow" the student's attention to the stimulus and, as a result, may prevent functional control from being transferred from the extraneous cue or prompt to the teaching stimulus (Schreibman, 1975; Schreibman, Charlop, & Koegel, 1982; Sidman & Stoddard, 1966, 1967). In SPH, students may attend more to the teacher's prompt than to the stimuli they are supposed to be discriminating. In addition, the delivery of extra-stimulus prompts to individual students during group instruction greatly reduces the number of trials that all the students in the group may receive.

The results of this study suggest that a fading procedure, when used in a concurrent group instruction model, may be an effective and efficient method for classroom instruction. Observer notes provide anecdotal data that the students appeared happier during TDM instruction, praised other students for correct responding, and asked if the teachers could use TDM more often. Observers also noted that students not included in these groups asked to be included and that teachers enjoyed the TDM procedure. For example, the teachers reported that they were able to observe and record their students' responses more accurately. Teachers either recorded each student's responses on a recording sheet as the students passed the materials, or directed students to record their own correct responses by placing a token in a small container placed in front of each student.

Further research is needed to confirm these anecdotal data, as well as to identify the types of tasks for which the TDM procedure is appropriate. Thus far, this procedure has been used to teach identification of common items that are part of daily routines (e.g., eating utensils, self-care items, clothing items), coins and bills, functional words and symbols, and equipment for vocational tasks (e.g., cleaning products, cooking utensils, assembly parts). Further information is required regarding the effect of TDM on maladaptive student behaviors, the ways in which teacher training can be best conducted, and how to select students most likely to benefit. A reasonable expectation would be that students must be relatively homogeneous to participate in a group. Yet, although the data in Table 2 show a difference in baseline of as much as 70% in correct responding, students in this group performed well together. Certainly, group teaching cannot be used for all tasks with students who have severe disabilities. With TDM, however, it might be used for students previously considered too disparate to function as a group.


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Author:Karsh, Kathryn G.; Repp, Alan C.
Publication:Exceptional Children
Date:Sep 1, 1992
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