printed by INTRODUCTION PARTICIPANTS AND SETTING Ann F. Filer, M/Ed., BCBA John Ward-Horner, Ph.D., BCBA-D Robert K Ross, EdD., BCBA-D Beacon ABA Services Wendy Kozma - Littleton, M.A. Evergreen Center Participant 1 was a 10-year-old girl with a diagnosis of developmental delay. She was in the second grade and attended a partial inclusion model for specials and language arts where spelling was taught. Participant 2 was a 14-year-old boy with autism who attended a 9 th grade, self contained classroom for all academic instruction. The study was conducted in the home of both students. The students were selected for participation in this study because they were not achieving passing grades on weekly spelling tests. An alternating treatments design was used to compare the effects of correct-after and correct- over error procedures on the acquisition of correctly spelled words. Participant 2 was exposed to a third condition that consisted of backwards chaining, which was alternated with the correct-over condition. The dependent variable was the number of trials to criterion for correctly spelled words in a 2- word set. After a set of words was mastered in one session, a new set was introduced in the next session. Furthermore, a 20-trial limit was in place for all sessions, such that if mastery criteria was not achieved, a new set was introduced during the next session. The words were randomly assigned to the experimental conditions. 321 Fortune Boulevard Milford, MA GENERAL PROCEDURE PROCEDURE. DESIGN Baseline: Each session began with a baseline probe to assess the participant’s performance at spelling the words. During baseline probes, the experimenter instructed the participant to spell each word twice. The experimenter did not prompt, reinforce, or error correct during baseline probes. Correct-After, Correct-Over, and Backward Chaining: Correct-over: Each trial began with the SD; “spell _____”. Verbal praise was given for all independent and correct trials. At the onset of each error, the experimenter guided the student to type or print the correct letter at the onset of an error, the instructor guided the student to print (participant 2) or type (participant 1) the correct letter. Correct-after: Each trial began with the instruction, “spell _____”. Verbal praise was provided for all independent and correct trials. The experimenter corrected errors after the participant attempted to spell the entire word by (a) saying, “try again, this time with me” and (b) physically guiding the student to write the word correctly. Backward chaining: Each word was divided into two letter steps (words with odd number of letter resulted in one step having one letter). Each trial began with the SD; “spell _____”. The experimenter would then physically assist this student to print each letter. Criteria was set at 100% correct and independent across 2 trials in order to fade assistance to the next two letters. Verbal praise was given for all correct trials in that step. Sel ected words for training were recommended by each participants classroom teacher who retrieved the words from a dolce site word list appropriate for his/her skill level. Maintenance for previously acquired words was assessed every session and calculated using percent correct. DATA The figures above display the number of trials to criterion for the correct-over, correct-after, and backward chaining procedure. For Participant1, the correct-over procedure resulted in fewer trials to criterion than the correct-after procedure. For Participant 2, the number of trials to criterion was similar across both the correct- over and correct-after procedures. However, the number of trials to criterion in the correct-over condition was significantly less than the backward chaining condition. Participant 2 did not reach mastery criterion with any word sets and as a result, the backward chaining procedure was terminated at trial 20, in all 3 sessions. The correct-over procedure may be a viable alternative to other teaching strategies. There are two important aspects that set this technique apart. First, it can reduce the probability of errors due to the blocking technique. Second, it is a simple procedure, requiring an adult to follow just two instructions (block and correct) versus multiple steps. This appeared to be the case with Participant 2. Prior to the onset of the study, treatment integrity was probed with his parent who was able to achieve 100% integrity for the correct-over procedure within one 10-minute session. Acceptable integrity was not achieved for the backward chaining procedure. Finally, a maintenance probe was conducted for Participant 2, he maintained 88% accuracy of newly acquired words, 30 days after the study had ended. The following are limitations to the present study; efficacy of this procedure was evaluated with only two students, follow up maintenance data were not collected with participant 1, and although IOA was measured at 100%, it was calculated in only14% of the overall sessions (5 out of the 21 sessions). Future research should compare the correct-over technique with other procedures such as constant prompt delay, exclusion and interspersing trials. In addition, the generality of these findings should be evaluated by implementing the correct over procedure with different target skills such as motor imitation and receptive picture identification. RESULTS AND DISCUSSION Antecedent or Consequence A Comparison of a Correct-Over, Correct-After and Backward Chaining with Site Word Spelling A traditional approach used to teach spelling to elementary school students is to provide a list of words, test for accuracy and provide feedback regarding errors (Dixon 1993). Response to errors often involves requiring the child to repeatedly write or verbally state the correct response (response repetition). This teach-then-test or trial and error approach is especially common when teaching students to spell irregular words because there are no rules or common features that can be applied to a sub-set of word groups to aid in memorization. Despite the many error correction options one could implement with this approach, providing an opportunity to produce an error is generally considered problematic, because of the greater probability of repeating similar errors, and once an error occurs, eradicating the embedded error is very difficult (Stella, 1983). Even when errors are minimized, as is the case in errorless teaching strategies, research suggests that the effects of repeated errors no matter how minor, are still detrimental to the learner and the learning process (Reed et al., 2011). An alternative response to trial and error is the use of a correct-over technique, frequently used in Direct Instruction reading and language programs. This technique is considered both a blocking and response to error procedure that is simple and effective in minimizing most if not all errors. The correct-over approach requires a teacher to intervene at the start of an error and use verbal or physical guidance to assist the student in producing the target skill correctly. Thus, the error is blocked and corrected before the student completes the response. Few studies can be found that have compared this technique with errorless teaching and error correction (correct-after) strategies. The purpose of this study was to compare the effects of a correct-after procedure and a correct-over procedure on the acquisition of irregularly spelled words in 1:1 ABA teaching sessions. This study also compared the effects of a backward chaining procedure to that of the correct-over technique for one of the participants.