The traditional idea of five specialized sense organs—eye, ear, nose, tongue, and skin—that make possible vision, hearing, smell, taste, and touch was expanded and deepened with the development of physiology. The vestibular apparatus, the receptor systems of the motor apparatus, and the numerous visceral receptors were investigated in both animals and man, as were the electroreceptor in fish. It was found that the perception of touch, pain, pressure, heat, and cold, combined in the sense of touch, is effected by various receptor structures of the skin. However, light can be perceived by, for example, such different organs as the human eye and the compound eye of insects. The variety of receptor elements of the sense organs led to the idea of the main types of reception, or sensibility—mechanoreceptor (for example, touch, phonoreception, or perception of sound, and vestibular reception, or perception of the spatial position of the body), chemoreception (taste, smell), and photoreception (light)—and the corresponding perceiving apparatus— the receptors . In man, more than80 percent of the information about the external world is received through the Eyes. Sensory system is a part of the Nervous system, responsible for sensory processing information. A sensory system consists of Sensory receptors, neural pathways and parts of the brain involved in sensory perception. Commonly recognized sensory systems are those for Vision, hearing,touch Taste and smellThe Receptive field rod or cone is the specific part of the world to which a receptor organ and receptor cells respond. For instance, the part of the world an eye can see, is its receptive field; the light that each can see by rods and cons in is its receptive field .So we can conclude that, the top most receptive field of eye have been identified for the Visual system and Eyes are the most effective sensory organs to learning about new products.
