We use a simple statistical model to simulate recent femtosecond experiments on the caging dynamics of I-2 in high pressure rare gas environments [Wan et al., J. Chem. Phys. 106, 4353 (1997)]. The collision-induced bound state motion in I-2 and its appearance in the pump/probe signal is perfectly reproduced in our calculation. In the case where He is used as the I-2 collision partner we find multiple collisions to be important. The numerical results can be explained analytically under simplified assumptions.