The effect of the pseudocontact term arises from magnetic anisotropy of the paramagnetic center (reflected in g-anisotropy in the EPR spectrum). This anisotropy creates a magnetic field which supplements that of the instrument's magnet. The magnetic field exerts its effect with both angular and a 1/r 3 geometric dependences.

The resonance frequency of a nuclear spin depends on the strength of the magnetic field at the nucleus, which can be modified by isotropic (e.g. chemical shift, isotropic J- coupling) and anisotropic interactions (e.g. chemical shift anisotropy, dipolar interactions).