  We consider the dynamics of self-propelled particles subject to external
torques. Two models for the reorientation of self-propulsion are considered,
run-and-tumble particles, and active Brownian particles. Using the standard
tools of non-equilibrium statistical mechanics we show that the run and tumble
particles have a more robust response to torques. This macroscopic signature of
the underlying reorientation statistics can be used to differentiate between
the two types of self propelled particles. Further this result might indicate
that run and tumble motion is indeed the evolutionarily stable dynamics for
bacteria.
