  We show that by switching on a spin-orbit interaction in a cold-atom system,
experiencing a Zeeman-like coupling to an external field, e.g., in a
Bose-Einstein condensate, one can simulate a quantum measurement on a
precessing spin. Depending on the realization, the measurement can access both
the ergodic and the Zeno regimes, while {the time dependence} of the spin's
decoherence may vary from a Gaussian to an inverse fractional power law. Back
action of the measurement forms time- and coordinate-dependent profiles of the
atoms' density, resulting in its translation, spin-dependent fragmentation, and
appearance of interference patterns.
