Equilibrioception: a Method to Evaluate the Sense of Balance

In this study, we present an algorithm for the assessment of one’s own perception of balance (equilibrioception). Upright standing position is maintained by continuous updating and integration of vestibular, visual and proprioceptive information, so that a compensatory reaction can be implemented when perturbations occur. This ability to monitor and maintain balance can be considered as a physiological sense, so, as for the other senses, it is fair to assume that healthy people can perceive and evaluate differences between balance states. The aim of this study is to investigate how changes in stabilometric parametres are perceived by young, healthy adults. Participants were asked to stand still on a Wii Balance Board (WBB) with feet in a constrained position; 13 trials of 30 s each were performed by each subject, the order of Eyes Open (EO) and Eyes Closed (EC) trials being semi-randomized. At the end of each trial (except the first one), participants were asked to judge if their performance was better or worse than the one in the immediately preceding trial. SwayPath ratio data were used to calculate the Just Noticeable Difference (JND) between two consecutive trials, which was of 0.2 when participants improved their performance from one trial to the next, and of 0.4 when performance on a trial was worse than in the previous one. This “need” of a bigger difference for the worsening to be perceived seems to suggest a tendency towards overestimation of one’s own balance. Interestingly, participants’ judgement was more reliable when evaluating consecutive EC rather than EO trials, at least when performance was worsening.