Light touch contribution to balance in normal bipedal stance

It has previously been shown that light contact with the finger tip on a fi xed surface reduces centre of pressure (CoP) fluctuations in the frontal pl ane when standing in an unstable posture with the feet in line (tandem Romb erg stance). Positive cross-correlations between horizontal finger forces a nd CoP fluctuations with finger forces exhibiting a phase lead suggest the hand provides sensory input for postural stability. The present study inves tigates whether this is the case for normal posture, We report reduced CoP fluctuations in the sagittal plane when light touch is permitted during nor mal bipedal stance. Moreover, we find positive crosscorrelations between fi nger tip forces and CoP fluctuations which are of similar magnitude and pha se lag to those observed in tandem Romberg stance. This shows the utility o f hand touch input fur regulation of normal upright posture as well as inhe rently unstable postures such as tandem Romberg.