Let's move away from the topic of branding for a moment to again focus on the importance of 1) using appropriate terminology, 2) describing procedures fairly and accurately, and 3) assessing research in light of a specific child's characteristics and the skill to teach. I spent a previous blog discussing requesting vs. labeling (mands vs. tacts) in this light. Let's now debate the question, "Which is better: conducting massed trials or task interspersal during discrete trial teaching?"

APPROPRIATE TERMINOLOGY

As we'll see later when we assess the research, it's important to identify exactly what we mean by massed trials and task interspersal. For the purpose of this discussion, I will define "massed trials" as: the repetition of the same S^D or similar unlearned tasks (e.g., " touch ball" or "touch my/your nose") at least three times. Task interspersal requires: the inclusion of reinforced maintenance tasks (e.g., the child has learned to touch the apple and shoe; the instructor asks the child to "touch shoe" or "touch apple" while also teaching "touch ball").

DESCRIBE PROCEDURES FAIRLY AND ACCURATELY

Note that massed trials, even in the research, do not require the S^D to be repeated 10 times in a row. Knowing the Lovaas Model of ABA sometimes uses massed trials, someone once asked me, "Which is better: extensive massed trials or task interspersal?" Words like "extensive" already bias the question. We want to make sure we are comparing each procedure in its best possible light. To this end, the definition of task interspersal allows that the maintenance task may or may not be related to the skill being taught (e.g., having a child imitate the instructor while teaching him to "touch ball" would still be task interspersal). However, task interspersal does not include interspersing multiple new tasks (e.g., teaching a child to "touch ball" "touch apple" and "touch shoe" all at the same time is not task interspersal). Again, wanting to present each procedure in the best possible light, research (Dunlap, 1984) already indicates that "task interspersal must include maintenance tasks, and that merely interspersing several acquisition tasks did not facilitate learning." (Charlop, 1992).

ASSESSING RESEARCH IN LIGHT OF A SPECIFIC CHILD'S CHARACTERISTICS AND THE SKILL YOU WOULD LIKE TO TEACH

As usual, the initial question, "Which is better..." is too simplistic. Different child characteristics and skill development issues should be taken into account. Further, the strength of the research evidence (e.g., is this a peer-reviewed research study, dissertation, or preliminary data?) should be taken into consideration.

Keeping these factors in mind, here's some of the relevant research to answer the question.

Dunlap (1980)

• Research Evidence: JABA article
• Child Characteristics: children with autism who demonstrated "large self-stims" or were "unresponsive to most environmental events"
• Skills Practiced: included early learner tasks (nonverbal imitation, matching)
• Conclusions Reached: massed trials (of 60-150 times in a session) resulted in a declining trend in correct responding while task interspersal resulted in an increasing trend in correct responding

Smith (1990)

• Research Evidence: unpublished dissertation
• Child Characteristics: children with autism, ages three to six
• Skills Practiced: included early learner tasks (handing an object)
• Conclusions Reached: massed trials resulted in faster acquisition but poor maintenance while task interspersal (in this case expansion trials) resulted in slower acquisition but better maintenance

Sallows (2000)

• Research Evidence: ABAI annual conference presentation
• Child Characteristics: children with autism
• Skills Practiced: included early learner tasks (labeling animals)
• Conclusions Reached: task interspersal of similar tasks (e.g., labeling other acquired animals) resulted in better maintenance than task interspersal of dissimilar tasks (e.g., imitating nonverbal actions)

Volker (2008)

• Research Evidence: JABA article
• Child Characteristics: children with autism who demonstrated "noncompliance during instruction"
• Skills Practiced: included early learner tasks (labeling objects)
• Conclusions Reached: massed trials resulted in faster acquisition; no benefit to task interspersal was found when highly preferred reinforcers were used in massed trials; however, task interspersal increased acquisition when only praise was used in both conditions

Based on this preliminary evidence, what kind of questions should we ask when deciding whether to use massed trials or task interspersal? Here's what I think:

1) Does this child respond well to a variety of reinforcers? If the answer is "no," then task interspersal may be appropriate. Task interspersal appears to allow for lower levels of reinforcement to be used and may increase the motivation of children for whom it is difficult to find effective reinforcers.

2) Is this child quickly learning new skills? If the answer is "no," then massed trials may be appropriate. Massed trials appear to result in faster acquisition initially. Once a child is correctly responding, other tasks can be systematically interspersed.

3) Does this skill require finer discriminations (e.g., a child ability to discriminate between a cow, pig, and sheep)? If the answer is "yes," then it may be more appropriate to intersperse similar tasks than to include dissimilar tasks (e.g., nonverbal imitation or receptive instructions).

Within the Lovaas Model of Applied Behavior Analysis, the most widely used teaching sequence involves a progression from massed trials to systematic expanded trials (a form of task interspersal). This approach can be altered for learners who have less or more difficulty acquiring new items. Modifications may include reducing or increasing the number of trials in the massed trial sequence, using systematically longer time intervals for the initial expansion, adjusting the type of maintenance items used in the expansion, and/or skipping steps in the expansion.

At the Lovaas Institute, what I've learned is that there are benefits to using massed trials, but the procedure is not the careless repetition of ten trials. Further, task interspersal is not only helpful but can be implemented in a variety of ways (e.g., using similar or dissimilar tasks, more or less systematically, etc.). Above all, I've learned at the Lovaas Institute that true individualization of a child's program involves a close look at the characteristics of the child, the skill that is being taught, and the data that has been collected.

Any comments or other relevant research I should have considered?

References
Charlop, M. H., Kurtz, P. F., & Milstein, J. P. (1992). Too much reinforcement, too little behavior: Assessing task interpersonal procedures in conjunction with different reinforcement schedules with autistic children. Journal of Applied Behavior Analysis, 25, 795-808.
Dunlap, G. (1984). The influence of task variation and maintenance tasks on learning and affect of autistic children. Journal of Experimental Child Psychology, 37, 41-64.
Dunlap, G., & Koegel, R. L. (1980). Motivating autistic children through stimulus variation. Journal of Applied Behavior Analysis, 13, 619-627.
Sallows, Glenn (early 2000). Presentation at Association for Behavior Analysis International Annual Convention.
Smith, T. (1990). Improving memory to promote maintenance of treatment gains in autistic children. Unpublished doctoral dissertation, University of California, Los Angeles.
Volkert, V., Lerman, D., Trosclair, N., Addison, L., & Kodak, T. (2008) An exploratory analysis of task-interspersal procedures while teaching object labels to children with autism. Journal of Applied Behavior Analysis, 41, 335-350.