Visual cognition is an important area of biocybernetics. It ranges from the filtering processes of early vision to the structural and functional organization of the visual centres, as well as, in higher animals, to the neuronal plasticity, the decision-making rules, the effect of noise, the role of attention, the ambiguity of patterns, and the time dimension. All these factors contribute to the cognitive interpretation of visual sensation that takes place in visual perception. A side field is machine vision, in which the signal processing known from animal vision is applied to the mobile robots responding to light stimulation.