A Comparison of 3 ABA Different Models

Discrete Trial Training is considered a more traditional ABA model, while Verbal Behavior and the CLM model are more contemporary type approaches. Discrete Trial Training , such as the one pioneered by Dr. Ivaar Lovaas stresses compliance training, imitation skills, and building receptive language for young, non-vocal early learners. The VB model, on the other hand, looks first at what the child wants and then teaches the child how to request (in VB terms, how to mand). Initially that may involve only the child reaching for the item to indicate interest. The child quickly learns that if he uses “verbal behavior” or reaching in this case, to indicate interest in something, he gets the item. Many VB consultants also recommend the use of sign language for most non vocal early learners while Lovaas consultants rarely recommend signing as a first step. In VB programs, early skills, such as manding, are usually taught away from a table and in the natural environment. Both Lovaas and VB programs are based on the principles of ABA so there are many similarities as well as a few key differences. (Pa Verbal Behavior Project Family Handbook, 2006).

A side-by-side comparison of the CLM and VB programs find many similarities and few differences. There are no large scale inter-group design comparison treatment studies to support either program, although they are both based on researched principles of effective instruction including ABA, Direct instruction and the Analysis of Verbal Behavior. Significant training is provided for staff in both of these programs to assure that they are carried out effectively. In the area of instruction, Verbal Behavior uses intensive teaching in 1;1 or dyads, where CLM begins in 1:1 and systematically moves to 1:2 , 1:3, 1:4 etc. both VB and CLM use natural environment teaching(NET) while verbal behavior also stresses errorless teaching procedures . There is a greater emphasis for non-vocal learners to establish an augmentative communication system with additional vocal training procedures in place.

In an article by Delprato (2001), researchers examined a series of 10 controlled studies in which traditional operant behavioral procedures were compared with more recently developed normalized interventions for teaching language to young children with autism. The main characteristics of the older treatments programs included highly structured direct teaching sessions of discrete trials, teacher initiation, artificial reinforcers, and response shaping. The programs that were considered a more normalized or contemporary use of ABA components consist of loosely structured sessions of indirect teaching with daily routines, child initiation, more natural reinforcers, and a liberal criteria for presentation of reinforcers. Two types of more contemporary ABA approaches considered were incidental teaching and pivotal response training. The conclusion was that in all eight studies, normalized language training was more effective than discrete-trial training. In addition, in the studies that assessed parental affect, normalized treatment yielded more positive affect than discrete-trial training.


CLM handout, Components of VB and CLM Projects, Side by Side Description, unknown source, February, 2009.

Delprato, Dennis. "Comparisons of Discrete-Trial and Normalized Behavioral Language Intervention for Young Children with Autism." Journal of Autism and Developmental Disorders 31.3 (2001): 315-325.