From Wikipedia on 14-Apr-2013
URL: http://en.wikipedia.org/wiki/Imagination
Imagination, also called the faculty of imagining, is the ability to form new images and sensations that are not perceived through sight, hearing, or other senses. Imagination helps make knowledge applicable in solving problems and is fundamental to integrating experience and the learning process.
It is accepted as the innate ability and process of inventing partial or complete personal realms within the mind from elements derived from sense perceptions of the shared world.
Imagination is an experimental partition of the mind used to develop theories and ideas based on functions. Taking objects from real perceptions, the imagination uses complex IF-functions to develop new or revised ideas. This part of the mind is vital to developing better and easier ways to accomplish old and new tasks. These experimental ideas can be safely conducted inside a virtual world and then, if the idea is probable and the function is true, the idea can be actualized in reality. Imagination is the key to new development of the mind and can be shared with others, progressing collectively.
Memory and imagination have been shown to be affected by one another. “Images made by functional magnetic resonance imaging technology show that remembering and imagining sends blood to identical parts of the brain.”
The world as experienced is an interpretation of data arriving from the senses; as such, it is perceived as real by contrast to most thoughts and imaginings.
Imagination, because of having freedom from external limitations, can often become a source of real pleasure and unnecessary suffering. Consistent with this idea, imagining pleasurable and fearful events is found to engage emotional circuits involved in emotional perception and experience. A person of vivid imagination often suffers acutely from the imagined perils besetting friends, relatives, or even strangers such as celebrities. Also crippling fear can result from taking an imagined painful future too seriously.
Imagination can also produce some symptoms of real illnesses. In some cases, they can seem so “real” that specific physical manifestations occur such as rashes and bruises appearing on the skin, as though imagination had passed into belief or the events imagined were actually in progress. See, for example, psychosomatic illness and folie a deux.
It has also been proposed that the whole of human cognition is based upon imagination. That is, nothing that is perceived is purely observation but all is a morph between sense and imagination.