The goal of this study is to investigate spontaneous postural synchronization between people who are visually coupled. The ongmaltty of the study is to conjointly analyze the postural and interpersonal coordination fields usually investigated independently from each other. Previous postural coordination studies have shown that multi-segment postural coordmation can be described by the relative phase between the hip and ankle in a suprapostural task (i.e., when posture is investigated within a goal-directed task). Research revealed that when participants track the sinusoidal motion of a target with their head, two stable patterns emerge: an inphase mode for low target frequency displacement and an anti-phase mode for high target frequency motion, corresponding to hip-ankle relative phases close to 20° and 180°, respectively.