The characteristic or condition of being attentive to threat and danger. Behavioral signs of vigilance are raised head and sensory focusing to survey the surroundings. Definition from Hurnik et al., 1995. Any behavior indicative of alertness to potential danger. Definition from Hurnik et al., 1995.
Vision is mediated by the specialized structures and visual receptors in the eye.
Definition from Hurnik et al., 1995. Such situations are used in the study of perception. Animals of some species or age will refuse to cross over onto a solid but transparent floor beyond a visual cliff. Definition from Hurnik et al., 1995. Definition from Hurnik et al., 1995.