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Muriel D, Saunders and Richard R. Saunders
Parsons Research Center
Parsons, KS 67357
Individuals with severe limitations in cognitive and motor skills present interesting challenges to the augmentative and alternative communication (AAC) provider. Many of these individuals are nonverbal and unable to make requests or signal needs in conventional ways. In the past 25 years a number of studies have demonstrated that some of these individuals can learn to use simple mechanical switches to control leisure devices; thus providing some control over their environments and a rudimentary way to communicate preferences (Ball, Combs, Rugh, & Neptune, 1977; Dattilo & Mirenda, 1987; Leatherby, Gast, Wolery, & Collins, 1992; May, 1983; Realon, Favell, & Dayvault, 1988; Saunders et al., 2001; Wacker, Berg, Wiggins, & Cavanaugh, 1985).
In a typical switch arrangement the switch is attached via a mini-plug or jack to a receptor on an adapted leisure device (e.g., usually a battery-operated device such as a toy with movable parts, tape player, radio). The leisure device is adapted with the addition of the switch by interrupting electrical current from the battery. When the switch is closed, the flow of current is restored, activating the device. When activation of the device serves as a reinforcer for switch closure, longer or more frequent switch closure is likely to be observed.
A critical component of switch-activated leisure programs is development of an effective method to demonstrate each individual's "contingency awareness." Contingency awareness refers to the observation that the number of switch closures or the length of time the switch it closed increases when the switch activates the leisure device relative to times when the device is not connected to the switch (Leatherby et al., 1992). A demonstration of contingency awareness is important for two reasons. First, confirming awareness validates continued participation in the switch-activated leisure program. Second, once the individual demonstrates contingency awareness, personal preferences can be assessed more reliably. In general, the more restricted the motor and communication repertoires of an individual, the more pressing becomes the need for an empirical demonstration of contingency awareness (i.e., objective, data-based evidence). False-positive assumptions about contingency awareness can lead to inclusion in costly or time-consuming efforts that produce little benefit; false-negative assumptions can lead to failure to assist the individual to achieve attainable independence and self determination.
Ordinarily, raw counts of switch closures are converted to expressions of switch-closure rate or frequency (i.e., the number of closures expressed relative to some unit of time). Unfortunately, as with raw counts, switch-closure rates may be extremely variable within and across recording sessions (Kennedy & Haring, 1993; Realon et al. 1988). For example, individuals with tremors and other movement disorders may have a low rate of volitional switch closure, but periodically close the switch involuntarily at higher rates.
Duration of switch closure, rather than rate, has been recorded in some studies. For example, Wacker et al. (1985) used duration measures to investigate the effects of a switch-activated program to increase a "sustained head raise." Measures of duration tend to focus the investigator on sustained periods of switch depression that might be more valid indices of volitional behavior than rate. Unfortunately, long durations can reflect periods of sleep or distraction during which the switch is unintentionally depressed. Duration data are reduced most often to the "percent of time" that the switch is closed per test or activity period.
Frequency and duration measures can be employed independently and provide distinct and important indices of behavior (Saunders et al., 2001). Frequency of switch depressions may provide information about whether sensory feedback from switch depressions, i.e., audible clicks or the movement itself is functioning as a reinforcer for switch depressions. Duration of switch depressions may be a better measure of switch behavior when activation of the leisure item is functioning as the reinforcer.
Few studies to date have reported both frequency and duration measures, however. Furthermore, few automated data collection devices are available commercially at the present time. Devices that are available for measuring rate of switch depressions often are limited to counts less than 100. Those that measure duration often require a computer to summarize the data.
The group currently supported and studied in our work is comprised of about 100 individuals with severe multiple disabilities. Generally, the absence of language and other forms of conventional forms of communication, severe limitations in voluntary motor movements, and suspected but difficult-to-measure sensory impairments, are the most common characteristics of these individuals. Inferences from adaptive behavior rating scales and some formal testing have led to diagnoses of probable profound mental retardation for all of these individuals.
The individual is prompted verbally and gesturally, either by physically assisting the individual or to activate the switch or by pointing to the switch. No further prompts are provided for the remainder of the activity period. The switch is placed in a location that can be depressed using a voluntary movement, as determined through an assessment by the professional staff. Most of the individuals in our facility have had years of exposure to switches. Data are collected 3-4 times per week for approximately 30-60 minutes per activity period.
We are presently collecting data using two different types of automated data systems. The first system, referred to below as the data box, collects data that are useful in making programmatic decisions about whether an individual responds differently across phases in a test of contingency awareness. It is also used to test for optimal levels of switch responding when testing leisure preferences, switch locations, and types of adaptive switches. The second system referred to below as the HOBO system is used primarily for research purposes. It permits us to do a microanalysis of sessions when a switch is provided. We have been using the HOBO system to look at optimal periods of time when switch use is highest. (Data will be presented of both types at the Csun Conference 2002).
Data box. A 17-1/2 x 12 cm metal box housing a counter, timer, and other electronic components serves as the automated data recorder (Questad & Cullinan, 1987, electrical schematic available upon request). All components were purchased through an electronics supply catalog. The box is connected in line between an individual's adaptive switch and adaptive device. When the switch is depressed, concurrently the counter advances one digit, the timer is activated, and the leisure device is activated immediately. Device activation continues and the timer advances digitally in increments of one- tenth of a minute until the switch is released. The cumulative number and cumulative duration of switch closures are viewable throughout the activity period on a display panel located on the side of the box.
HOBO state logger. Data on rate and duration of switch depressions are collected using a small event recorder called a HOBO(r) State data logger (Onset Computer Corp.) and a software program called BoxCar(r) Pro (Onset Corp.). The data are transferred and stored temporarily in a unit called a HOBO(r) Shuttle until they can be transferred to a host computer (Dell Dimension 8100) using the BoxCar(r) Pro program. Next, data are transferred to a software program called Insight (formally BarCR, Saunders, Saunders, & Saunders, 1993) written in File Maker Pro(r) 5 where data are sorted and summarized. The summary includes:
(1) session length in seconds,
(2) frequency and duration in seconds of events (switch on and switch off),
(3) rate (frequency/session length) of events,
(4) percent of session (duration/length of session) of events,
(5) average duration (duration/frequency) of events,
(6) All of the above information for the 1st-4th quarters (length of session in seconds/4 and reported in consecutive segments of time).
Before data collection is begun, the staff person supervising the switch activity connected the data logger, switch, and leisure device to a relay box. Next, the microswitch was depressed for approximately 1 second to mark the beginning of the session with a time stamp and numerical code for a switch-on event. Data collection is then begun by positioning the microswitch in front of the participant. Each switch depression, of 0.5 sec or more in length, and release by the participant then is recorded using a time stamp and event description (i.e., a different numerical code for switch-on and switch-off events). At the end of the session, the staff person depresses the switch for approximately one second to mark the end of the session.
Samples of results from our data-collection methods will be shared. A discussion of the importance of multiple approaches to data collection and interpretation will be provided, using the data samples as points of reference.
The use of automated data systems for the collection of duration and frequency of switch depressions have made it possible to make informed decisions about the effectiveness of our switch program. The systems have also added to the research of switch behavior in this population. We are presently working with a vender to make a data collection device that will report both frequency and duration data without the use of a computer. This product should be available in the spring of 2002.
Ball, T. S., Combs, T., Rugh, J., & Neptune, R. (1977). Automated range of motion training with two cerebral palsied retarded young men. Mental Retardation, 15, 47-50.
Dattilo, J., & Mirenda, P. (1987). An application of a leisure preference assessment protocol for persons with severe handicaps. Journal of the Association for Persons with Severe Handicaps, 12, 306-311.
Kennedy, C. H., & Haring, T. G. (1993). Teaching choice making during social interactions to students with profound multiple disabilities. Journal of Applied Behavior Analysis, 26, 63-76.
Leatherby, J. G., Gast, D. L., Wolery, M., & Collins, B. C. (1992). Assessment of reinforcer preference in multi-handicapped students. Journal of Developmental Disabilities, 4, 15-36.
May, D. C. (1983). The use of an electric switch to increase independent head control in a severely handicapped student. Journal of Special Education Technology, 4, 14-19.
Questad, K., & Cullinan, T. (1987). A reinforcer driven, data based rehabilitation program for severely brain injured adults. Archives of Physical Medicine and Rehabilitation, 68, 674.
Realon, R., Favell, J. E., & Dayvault, K. A. (1988). Evaluating the use of adapted leisure materials on the engagement of persons who are profoundly, multiply handicapped. Education and Training in Mental Retardation, 23, 228-237.
Saunders, M. D., Timler, G., Pilkey, S., Questad, K. A., Cullinan, T. B., & Saunders, R. R. Enabling control of environmental events with adaptive switches: A tutorial on data acquisition and interpretation (2001). Submitted for publication.
Saunders, M. D., Saunders, J. L., & Saunders, R. R. (1993). A program evaluation of classroom data collection with bar codes. Research in Developmental Disabilities, 14, 1-18.Wacker, D. P., Berg, W. K., Wiggins, M. M., & Cavanaugh, J. (1985). Evaluation of reinforcer preferences for profoundly handicapped students. Journal of Applied Behavior Analysis, 18, 173-178.
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