Participants attempted to complete a 30-s evaluation of postural sway under two conditions: first with eyes opened (EO) and then with eyes closed (EC). While wearing their typical shoes, participants stood comfortably on a single force plate (AMTI, Watertown, MA, USA), with feet approximately shoulder-width apart, during one trial for each condition [12 (link),13 (link)]. Participants were instructed to “stand as still as a statue” for each condition. A second trial was attempted if the child did not stand still [6 (link)]. During the EO trial, an image was placed near eye level approximately four meters away [12 (link)]. The EC trial began immediately after the participant closed his or her eyes. Participants received at least one minute of rest between conditions.
Forces and moments were recorded at 1000 Hz (n=1) and 1200 Hz (n=40, discrepancy due to investigator error). The resulting COP time series was down sampled to 600 Hz and then filtered using a fourth order recursive Butterworth filter with a low-pass cutoff frequency of 10 Hz.
Forces and moments were recorded at 1000 Hz (n=1) and 1200 Hz (n=40, discrepancy due to investigator error). The resulting COP time series was down sampled to 600 Hz and then filtered using a fourth order recursive Butterworth filter with a low-pass cutoff frequency of 10 Hz.