Time asymmetry index for typical control group and the group of infants at high risk for autism is shown. The index was averaged over all infants in the group and age categories. If time asymmetry varied randomly at channel locations, the fluctuations would average out. The persistence of time asymmetry values different from zero indicates nonlinearity in the signal.
Bosl et al. BMC Medicine 2011 9:18 doi:10.1186/1741-7015-9-18