MODELS OF BEHAVIORS WHEN DETECTING DISPLACEMENTS OF JOINTS

This report describes two models of human behavior when detecting disp lacements of joints that allow one to compare and integrate findings f rom different proprioception tests in a quantitative way. Results from various tests have led to different and often conflicting conclusions about proprioceptive behaviors and their underlying neural mechanisms . However, it has been impossible to compare data and conclusions in a ny meaningful way due to lack of a suitable analytical framework to ac commodate important differences in procedures used in the various test s. These models can provide one such framework. The models, developed using data from proprioception tests reported in the literature, descr ibe how the amplitude and velocity of joint excursions, and the subjec t bias expressed as false alarm rate, affect the detectability of disp lacements of joints. Two models were needed to represent observed beha viors: one based on velocity signals alone (the velocity model) and th e other based on both velocity and positional signals (the displacemen t-velocity model). To simulate the detection-decision process subjects used to determine whether a joint was displaced, we adapted strategie s from signal detection theory. The models characterized reported beha viors from disparate proprioception tests remarkably well, requiring o nly 3 degrees of freedom in the velocity case, and 4 in the displaceme nt-velocity case.