 What states are preferred will depend on the details of the interaction, but in many cases, interactions are characterised by potentials that are functions of position, so preferred states are often related to position. For the chiral molecule, the left- and right-handed states are indeed characterised by different spatial configurations of the atoms in the molecule. For the harmonic oscillator, one should think of the environment ‘measuring’ approximate eigenstates of position, or rather approximate joint eigenstates of position and momentum, so-called coherent states (since information about the time of flight is also recorded in the environment). 