Motion-induced interruptions and postural equilibrium in linear lateral accelerations.

This study assesses lateral tipping motion-induced interruptions (MIIs) in a simulated motion environment. The objective is to revisit MII occurrence and sway motion relationship by focusing on the frequency and acceleration of the lateral motion stimulus. Results verify that MIIs increase with increasing peak sway acceleration, but the effect of sway frequency is not as clear as that of acceleration. Complex multidirectional motions create more tipping MIIs than unidirectional motion. Research should incorporate acceleration, frequency and motion complexity as factors influencing MII occurrence. To describe a temporary loss of balance without tipping, the term 'probable' MII is introduced. This term fills the gap between the theoretical definition and a human-centred perception of an MII where loss of balance is not a binary phenomenon. The 'probable' MIIs were 16-67% more common than the 'definite' MIIs. The developed mathematical model of MII occurrence versus sway acceleration (amplitude, frequency) approximated the observed MIIs with less than 9% difference.