Utilization of Sensory Information in Intellectual Disabilities

1. Utilization of Sensory Information in Intellectual Disabilities Michael Horvat

2. Introduction • A common problem associated with intellectual disabilities is the lack of ability or misuse of sensory information to establish stability and initiate movement. For individuals with intellectual disabilities, restriction or deterioration of these functions may impede the ability to monitor and adjust sensory feedback in order to maintain stability.

3. Participation • Eight individuals with mild intellectual disabilities (MID), eight individuals with Down syndrome (DS), and eight individuals without intellectual disabilities (WID) were recruited from local public schools and the Motor Development Clinic at The University of Georgia.

4. Instrumentation • Balance was assessed by computerized dynamic posturography performed on the NeuroCom Equitest System (NeuroCom International, Clackamas, OR). This system utilizes transducers located in a force platform which measure vertical and horizontal forces that are produced by the body’s movement around a fixed base of support.

5. Procedure • The Sensory Organization Test (SOT) requires participants to be tested under six conditions consisting of three 20-second trials with their eyes open or closed. During the test, a participant’s visual surround, force platform, or combination of both, are sway referenced. According to (Guskiewicz2001), the term sway referenced refers to the tilting of the support surface and/or visual surround to document the sway in the center of gravity. In other words, as the subject sways, the walls or support surface will move forward or backward accordingly. The conditions differ, depending on the manipulation of the somatosensory, visual, and/or vestibular environments, and the participant’s resulting movements are measured and recorded. The sway referencing delivers erroneous information to the sense, and the force platform measures the participant’s ability to rely on the other senses to compensate for the erroneous feedback being received (see Table 2). Each participant used a harness during testing to eliminate the risk of falling.

7. Scoring • Results from the SOT on the NeuroComEquitest System were used for all comparisons of the participants’ postural stability under six sensory conditions. Effective use of the individual’s sensory inputs is determined from the overall pattern of scores on each of the six conditions. The equilibrium composite score quantifies scores on all sway conditions and characterizes an individual’s overall level of performance from 0-100 (NeuroCom International 2000). Scores under 70 are generally considered to increase susceptibility to falls and instability. In addition, individual equilibrium scores on all six conditions were compared to extreme responses under varying movements and sway referenced conditions. Sensory analysis ratios were also used in conjunction with individual’s equilibrium scores to identify components of an individuals’ sensory system (NeuroCom International 2001). Ratio scores provide an estimate of how the sensory system compensates for the lack of reliable information that the condition contrived.

8. Results • To determine the effect of group (individuals with MID, individuals with DS, individuals WID), gender, and balance on the Sensory Organization Test (SOT) separate 3x2x7 (group x gender x SOT-condition scores) and 3x2x3 (group x gender x SOT-ratio scores) repeated measures analysis of variance (ANOVA) were performed.

11. Discussion • Based on the data analysis, an overall group difference was observed, with the DS group performing lower on the overall equilibrium composite score. Specifically, individuals with MID and DS performed worse during sensory conditions 3, 4, 5, 6, when the use of visual, vestibular and somatosensory information was disrupted.

12. Although there is a large volume of research in the area of motor behavior and intellectual disabilities, the understanding of how sensory information is used in movement control and the variations in performance for individuals with intellectual disabilities and those with Down syndrome is still lacking. In our investigation, differences were observed between groups, as the DS group scored lower during sensory conditions that emphasize visual and vestibular information, while somatosensory information seems appropriate and functional for each group.

13. From a teaching perspective, these findings provide critical information on how we should present sensory information in the learning process. Apparently, providing proper positioning and fell for the movement is more beneficial for learning in individuals with intellectual disabilities and Down syndrome. This may be accomplished by a physical prompts or guiding an individual through the movement in contrast to presenting a visual model or to assume a position that requires vestibular input. In this context, use of vision or continual information from the vestibular apparatus is not as effective in learning or monitoring movement For example in a clinical setting (Pediatric Exercise and Motor Development Clinic) the authors utilized tactile prompts to teach specific Tae Kwan Do movement forms to individuals with ID and DS. Practice was variable going from using single movement to integrating several sequences that constitutes a form. Also, practice started with placing the individual in the proper positions prompting them through the movement before presenting the movement with a visual prompt. By engaging the individual with the tactile movement, we were able to generate the specific task and then pair the tactile and visual sequence together. Variable practice was then used by first having the learner repeat the movement and then varying the response required in the form sequence.

14. Likewise, a similar procedure was used in the work environment to teach proper lifting techniques to individuals with ID by physically prompting bending knees and keeping the back straight before visually demonstrating the procedure. Again, practice was variable by repeating one movement successively before demonstrating variable sequences required to complete specific tasks in the work environment.

15. In order to maximize performance in changing environments and conditions, a multifaceted approach to learning should be utilized to focus on several facets that impact learning: (a) assess all the sensory capacities of individuals with intellectual disabilities; (b) develop feedback paradigms emphasizing the utilization of specific sensory input; (c) provide activities to facilitate balance and muscular functioning; and (d) provide variable practice activities to provide sensory information in different contexts to facilitate learning. This procedure will allow the instructor to know what sensory information is functional and how to structure the experience to engage the individual cognitively and physically to perform the movement.