In addition to manifesting social difficulties, persons with autism often manifest other anomalies such as atypical sensori-motor integration.
We investigated visuo-motor integration in autism by assessing the development of postural regulation for children with and without high-functioning autism (HFA) between the ages of 12 through 25 years.
Postural reactivity was assessed for 12 children with HFA and 19 typically developing children (TDC) whose ages ranged from 12-25 years. They stood within a virtual tunnel that oscillated in an anterior-posterior fashion at 0.125Hz, 0.25Hz and 0.5 Hz. The tunnel was presented using a fully immersive virtual environment system. Body sway and instability index were measured.
For Instability Index, a significant difference between children with HFA and TDC was found for the 0.5Hz frequency with increased instability for the HFA. We also found significant differences for body sway for 0.5 Hz showing a reduced postural response to this frequency. Other temporal frequencies did not show significant differences between groups for either dependent measure.
Persons with HFA seem to perceive and integrate certain visual stimuli as well as TDC (0.125Hz and 0.25Hz) but have difficulties integrating other types of stimuli (0.50 Hz). This is likely to be due to dysfunctions of multimodal brain areas but not of primary receiving areas for processing this type of information because the stimuli used were composed of very salient and high contrast moving checkerboard patterns. There is clear evidence that the HFA have sensitivity levels for luminance defined motion stimuli similar to that of TDC . Furthermore, the condition showing significant effects between groups (0.5 Hz) generated higher levels of instability meaning that the stimulus was indeed visually perceived; otherwise we would expect a null or reduced visually driven postural reactivity. We emphasize the importance of visual parameters to determine the influence of vision on postural control in HFA.