Chih Hui Chang

Visual tasks and postural sway in children with and without autism spectrum disorders

We investigated the influences of two different suprapostural visual tasks, visual searching and visual inspection, on the postural sway of children with and without autism spectrum disorder (ASD). Sixteen ASD children (age=8.75±1.34 years; height=130.34±11.03 cm) were recruited from a local support group. Individuals with an intellectual disability as a co-occurring condition and those with severe behavior problems that required formal intervention were excluded. Twenty-two sex- and age-matched typically developing (TD) children (age=8.93±1.39 years; height=133.47±8.21 cm) were recruited from a local public elementary school. Postural sway was recorded using a magnetic tracking system (Flock of Birds, Ascension Technologies, Inc., Burlington, VT). Results indicated that the ASD children exhibited greater sway than the TD children. Despite this difference, both TD and ASD children showed reduced sway during the search task, relative to sway during the inspection task. These findings replicate those of Stoffregen et al. (2000), Stoffregen, Giveans, et al. (2009), Stoffregen, Villard, et al. (2009) and Prado et al. (2007) and extend them to TD children as well as ASD children. Both TD and ASD children were able to functionally modulate postural sway to facilitate the performance of a task that required higher perceptual effort.

Perceiving Affordances for Aperture Passage in an Environment–Person–Person System

ABSTRACT The authors investigated the perception of affordances for aperture passage in an environment–person–person (E–P–P) system, which comprised an adult perceiver and a child as a companion. Perceivers were 8 large and 8 small female undergraduates and were companioned with 1 large and 1 small girl. The perceivers perceptually judged the minimum aperture width for the E–P–P system, and then the adult–child dyads (a pair of people) actually walked through to determine the systems actual minimum aperture width. Results demonstrated that perceivers precisely judged the action capabilities of an E–P–P system on the basis of the body-scaled information of each adult–child dyad. The findings extended the previous concept of affordances for an environment-person system to affordances for an E–P–P system.

Perception of Object Length Via Manual Wielding in Children With and Without Developmental Coordination Disorder

ABSTRACT The authors compared haptic perception via active manual wielding in children with and without developmental coordination disorder (DCD). Forty-eight children, 11–12 years old, participated as volunteers. Twenty-four were typically developing children (TDC), and 24 had been diagnosed with DCD. Individually, children held and wielded unseen rods of five lengths (20, 45, 60, 75, or 90 cm). Based on this wielding, children judged the length of each rod. Judgments of rod length were shorter in the DCD group than in the TDC group. In addition, significant interactions revealed that the difference between the 2 groups was progressively greater for longer rods. The results provide support for the hypothesis that DCD includes deficits in the ability to use manual wielding in the perception of object length. In addition, the results suggest that the deficit is not general, but is greater for longer objects.

Effects of decades of physical driving on body movement and motion sickness during virtual driving

We investigated relations between experience driving physical automobiles and motion sickness during the driving of virtual automobiles. Middle-aged individuals drove a virtual automobile in a driving video game. Drivers were individuals who had possessed a driver’s license for approximately 30 years, and who drove regularly, while non-drivers were individuals who had never held a driver’s license, or who had not driven for more than 15 years. During virtual driving, we monitored movement of the head and torso. During virtual driving, drivers became motion sick more rapidly than non-drivers, but the incidence and severity of motion sickness did not differ as a function of driving experience. Patterns of movement during virtual driving differed as a function of driving experience. Separately, movement differed between participants who later became motion sick and those who did not. Most importantly, physical driving experience influenced patterns of postural activity that preceded motion sickness during virtual driving. The results are consistent with the postural instability theory of motion sickness, and help to illuminate relations between the control of physical and virtual vehicles.

Walking Before and During a Sea Voyage

Stationary and moving surfaces impose different constraints on walking. In this study we investigated within-participants differences between walking on a ship before (at the dock) and during (at sea) a sea voyage. Four individuals participated in the study. While on the ship they wore a tri-axial accelerometer (ActiGraph GT3X+; ActiGraph LLC, Pensacola, FL) on their waists. Activity data were sampled at 30 Hz. Data were collected on the day before the voyage began and on several days at sea. The number of steps per day was greater at the dock than at sea. The net resultant force per day also was greater at the dock than at sea. However, resultant force per step was greater at sea (79.97 ± 8.50 vector magnitude counts/step) than on land (62.94 ± 10.03 vector magnitude counts/step). In addition, we observed variations in resultant force per step across days at sea. Ship motion decreased overall activity but increased the force per step.