Nature and Varieties of Stimulus

The external environment surrounding us is full of a wide variety of stimuli. Some can only be seen (a building), some can only be heard (a piece of music), some can only be smelled (the fragrance of a flower) or tasted (the sweetness of a sweet dish), and still others can only be experienced by touch (the softness of a piece of cloth). Each of these different kinds of stimuli supplies its own distinct kind of information, and human beings possess highly specialised sense organs to deal with each of them. As human beings, we are equipped with a set of seven sense organs in total. Five of these -- the eyes, ears, nose, tongue, and skin -- collect information directly from the external world: the eyes are primarily responsible for vision, the ears for hearing, the nose for smell, and the tongue for taste, while the skin is responsible for the experiences of touch, warmth, cold, and pain (with specialised receptors for warmth, cold, and pain located inside the skin itself). Beyond these five external senses, we also possess two deep, internal senses -- the kinesthetic and vestibular systems -- which supply important information about the position of our body and the movement of our body parts relative to one another. Between these seven sense organs, we are able to register ten distinct varieties of stimulus information -- for instance, with light we can notice whet …