Receptors, such as the eye, the ear, the organs of smell and taste, and the more diffuse sensory equipment of the skin, are found in all higher animals. Not all of the senses are equally helpful to the organism; the hawk's keen visual acuity is well documented, as is the bat's auditory sensitivity to meaningful echoes and the bloodhound's perception of olfactory clues. Although man derives comfort from touch and the pleasures of odors and tastes, his world is largely regulated by sound and light, calling into play the senses he finds most valuable in communication, navigation, and detection of objects at a distance. The conception of size, shape and color, or proximity and remoteness of light and shade, assist us in relating to our environment to a much greater degree than do the other senses. For example, texture, essentially a function of touch, can be conveyed visually from distant objects, after the individual has had sufficient preliminary experience. Through experience and association, we can conceptualize sensations of sound, touch, pain, temperature, taste, and odor by merely viewing the stimulus object. Misjudgments, of course, are known to occur.