Previous research has shown that stimuli rendered invisible through masking can be sufficiently processed to induce nonconscious influences and facilitate subsequent recognition. However, masking paradigms are methodologically restricted such that stimuli cannot be presented for longer than a few tens of milliseconds, potentially restricting the strength of nonconscious influences. By adapting a masked face repetition priming paradigm to a recent interocular suppression method, we investigated whether longer periods of invisible prime stimulation lead to larger nonconscious influences on subsequent recognition. Surprisingly, we found that while brief periods of invisible prime stimulation result in classical facilitation priming, long periods of invisible stimulation lead to negative priming influences, reflecting impairment of subsequent recognition. In contrast, when the prime was visible, longer exposure resulted in classical facilitation effects, revealing qualitative differences between conscious and nonconscious processes. Altogether, the present findings reveal the existence of a nonconscious overstimulation cost, as well as an important dissociation between conscious and nonconscious processing.