The reactivity of neurones in the superior colliculi to the movement of the optic stimulus was studied in monocularly and binocularly deprived rabbits (MD and BD). Deprivation was effected by suturing the eyelids before the eyes opened. The neurones were classified into three groups by the degree of their directional selectivity (absolute, relative and zero). The effect of a prolonged (ten weeks or more) early MD consisted in the absence of collicular units with absolute selectivity. Proceeding from the existence of such units in the MD type rabbits in the third week of their life, it is suggested that prolongation of the MD time leads to their functional reduction. As the recorded characteristics of unit responses do not change in BD rabbits, it is assumed that the MD effect is not linked to limiting the function of vision and is just a consequence of a prolonged asymmetry of optic stimulation. The deprivation effect at the collicular level in different vertebrates is discussed.