We have used an optogalvanic method to detect observables induced by optical pumping in metastable states of neon. As with optical methods signals are obtained due to electronic and nuclear orientation or alignment. Different mechanisms are discussed from which optogalvanic signals related to non-scalar observables may originate. Profiles obtained from frequency sweeps of two polarisation-modulated counterpropagating pump beams indicate the dominant mechanism is a second-order pumping effect which induces a modulated depletion of the metastable state.