The infrared predissociation spectrum of t-butyl hydroperoxide excited to the 4-nu-OH level reveals extensive mixing between the zeroth-order OH stretch state and nearly isoenergetic zeroth-order dark states. Because most of these dark states have an OH stretch quantum number of zero, the predissociation spectrum strongly resembles the infrared spectrum of an unexcited molecule. The observed intensity distribution in the predissociation spectrum is what one would expect if the eigenstates prepared by 4-nu-OH vibrational overtone excitation were statistical mixtures of all the nearly isoenergetic zeroth-order states.