In this paper we use pupillometry, a non-invasive, naturalistic method of measuring attention and cognitive load, to mea- sure the effect of stress clash (Chi.NESE ship) and its metrical repair (CHI.nese ship) during auditory sentence processing. We addressed two main research questions. The first question explores whether phonologically-disfavored metrical structure induce processing costs indexed by changes in pupil size.The second investigates whether the application of an optional pro- cess of stress retraction called the Rhythm Rule (Liberman & Prince, 1977) ameliorates or compounds any general penalty for stress clash. We find that unrepaired stress clash leads to greater pupil diameter relative to non-clashing sequences, indicating increased attention and cognitive load. We also find that repaired potentially-clashing sequences lead to a decrease in overall pupil diameter, indicating facilitation.