relation
between parts of the body
with the body
treated
articulated axes
important feature
same
movementscan
notated
several polar
coordinate systems
coordinatesof
determined
reference
environment
midline axis
subject’s body
next proximal ordistal limb
body segment
primary value
socialinteractions
describedas
relative to the body of the other animal (Moran et al., 1981; andsee Appendix A in Pellis et al., 2013 for a detailed outline of howthe system is used to record the behavior of two interacting ani-mals). By transforming the description of the same behavior fromone coordinate system to the next, invariance in the behavior mayemerge in some coordinates but not others (Golani, 1976).