Determinants of psychophysical detection thresholds for young adults on a horizontally translated platform

The ability to detect a perturbation may be important for producing an adequate postural response to maintain balance during and after a perturbation. The center of pressure is a composite measure of the postural adjustments that occur in order to maintain the center of gravity over the base of support. We describe a method for discerning if the initial and subsequent positions and velocities of the anterior-posterior center of pressure impact the ability of subjects to detect a 20 mm forward translation of a force platform on which they were standing. The platform movements occurred at the subjects' acceleration detection threshold, which was determined from a psychophysical testing paradigm, using a novel balance testing system. Phase plane analysis of the center of pressure profiles during translation revealed differences in translations that were detected versus those not detected.