Low‐level electrostatic ion acoustic turbulence generated by the ion–ion beam instability was investigated numerically. It is demonstrated that a conditional statistical analysis can reveal the formation, propagation, and decay of negative potential wells which correspond to ion phase‐space vortices. While the statistical analysis gives results in terms of averages over a conditionally selected subensemble,individualphase‐space structures can be investigated by small clusters of test particles placed at selected positions in phase space. The predictions of the conditional statistical analysis can be tested and their accuracy estimated by this method. A discussion of various aspects of test particle dynamics in turbulent plasmas follows naturally, with particular emphasis on conditioned particle release and relative diffusion of particles. The statistical properties of the fluctuating electric fields sampled along Lagrangian particle orbits is analyzed.