Comparison of the effects of three approaches on the frequency of stimulus activations, via a single switch, by students with profound intellectual disabilities.

The effects of three classes of reinforcing stimuli were compared across three students with profound intellectual disabilities. A multielement design with no baseline and final "best treatments" phase was used to measure the frequency of single-switch activations by each student across treatments. The three interventions were Treatment A, adapted toys and devices; Treatment B, cause-and-effect commercial software; and Treatment C, instructor-created video programs. Stimulus activations using a single switch were consistently greater when using individualized computer-based video programs. Implications for identifying stimuli for students who may not respond to traditional methods for teaching means--end contingencies (cause and effect) are discussed.

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Students with profound disabilities who are nonverbal and have limited control over their movements have been identified as the most challenging in the field of behavior analysis (Ivancic & Bailey, 1996). Providing quality educational programs to these students presents a tremendous challenge (Smith, Gast, Logan, & Jacobs, 2001). Students with severe and profound intellectual or physical disabilities experience limitations in their ability to interact with their environments (Daniels, Sparling, Reilly, & Humphry, 1995) and to learn action (means)--outcome (end) contingencies (Sullivan & Lewis, 1993), also known as cause and effect. Assistive technology, including switches, alternative and augmentative communication devices, and environmental controls, provides an alternative means for students to access their environments, exert control, express themselves, and learn simple tasks (Cook & Hussey, 2002; Daniels et al., 1995). Activation of a single-switch device requires fine or gross motor movements to deliver force through contact with the switch or detection of motion, sound, or light (Brett, 1995). Switch devices serve as an interface between the student and a battery-operated (e.g., portable CD player, jumping toy rabbit, and radio) or plug-in device (e.g., fan, tape recorder, and water pick) through a wired connection transporting an electronic current to target stimuli (Goossens' & Crain, 1992). Students may further learn that their actions (i.e., pressing a switch) can communicate leisure preferences (Dattillo, 1987), wants and needs, or other information (Dyches, 1999). A single activation of a switch with voice output, operating as a communication device, can enable participation in activities such as the "Pledge of Allegiance," reading a lunch menu, weather discussions, singing repetitive lines in a song, and greeting others (Dyches, 1999).

Studies report the ability of students with severe intellectual disabilities to learn single-switch access (Flanagan, 1982; Lancioni et al., 2002; Meehan, Mineo, & Lyon, 1985; Wacker, Wiggins, Fowler, & Berg, 1988) and to benefit from its use (Johnston, 2003; Lancioni, O'Reilly, & Basili, 2001; Sullivan & Lewis, 1993), including learning cause and effect and control over one's environment (Langley, 1990). Traditionally, teaching cause and effect through switch activation has involved the use of battery-operated toys and devices (Johnston, 2003); however, a limitation with this approach is the provision of variety. Providing a variety of stimuli has been identified as a key component in teaching switch technology (Daniels et al., 1995; Sullivan & Lewis, 1993), yet budgets may restrict the purchase of several reinforcing devices. Teachers may have access to only one or two toys, limiting the rate of skill acquisition due to boredom by the switch user, who finds little difference between a walking, oinking pig and a walking, mooing cow (Johnston, 2003).

In addition to toys and small appliances, a variety of commercially developed computer software programs are available to teach cause and effect via a single switch and switch interface. These programs typically provide motivating features, such as light, sound, music, and animation. Cost may likewise limit the number and variety of programs available in a typical classroom setting, and some teachers may use the same program all year to teach cause and effect to a particular student. Furthermore, the need for repetition in teaching concepts to this population of students may result in reinforcers losing their effectiveness (satiation) and the students losing interest when the reinforcers are repeatedly presented during teaching sessions or used over a long period of time (Murphy, McSweeney, Smith, & McComas, 2003). A challenge, therefore, is to maintain sustained interest and novelty among task materials and reinforcing stimuli when repetition is required.

The challenge to provide novelty is further compounded when children with severe and profound disabilities exhibit little or no interest in commercially available toys and materials that readily excite children without disabilities, leaving teachers, parents, and therapists with the difficulty of identifying stimuli that hold meaning and interest for these students. Procedures for conducting reinforcer stimulus preference assessments for students with profound disabilities have been reported (Ivancic & Bailey, 1996; Leatherby, Gast, Wolery, & Collins, 1992; Logan et al., 2001; Wacker, Berg, Wiggins, Muldoon, & Cavanaugh, 1985), along with the impact of identification on student response and task performance (Gast et al., 2000; Smith et al., 2001), yet identification of consistent reinforcers can be extremely difficult and complicated (Gast et al., 2000). Whereas Logan et al. reported a direct correlation between lack of progress in learning new skills and the lack of identification of effective reinforcers, Logan and Gast (2001), in their review of the literature on preference assessments, further identified a need to incorporate results of preference assessments into instruction and activities for persons with profound intellectual disabilities. Presented with the possibility that students do not increase their levels of switch use because of their limited interest in contingent stimuli (Lancioni et al., 2001), designers of programs for teaching cause and effect must address the interest of the learner by providing examples and experiences that hold meaning to the student who may have very unique or limited interests. Greater difficulty is presented when meaningful activities or persons that hold meaning for the student are not readily available in the instructional setting (e.g., riding a pony, father chopping wood, garbage trucks, family pets, siblings, and grandparents).

The current study evaluated three approaches for teaching switch-activated cause and effect, including video technology, as a means for providing familiar activities or persons out of context within the classroom setting. This form of video ...