<p>A series of experiments has demonstrated that a prolonged period of monocular deprivation (up to 14 days) produces no change in the CFF of the occluded eye. However, the performance of the non-occluded eye is characterized, first, by an initial depression or impairment of the CFF and, second, by a subsequent enhancement effect of a progressively increasing magnitude. Furthermore, this interocular effect in the non-isolated eye was still present 14 days <em>after </em>the termination of deprivation. These findings are related to Sharpless’s (1964) concept of “disuse of neural pathways.” In addition, some general implications of these results for research in the area of sensory deprivation are discussed.</p>