Imagination is supposed to be the simplest and most basic form of thinking. Let us assume that a man, one night after a heavy meal, sits at the window of his bedroom and keeps looking at the full moon outside. Several objects and impressions appear before his eyes in a random and unconnected manner. This type of activity is known as imagination and occurs without any specific effort.
Imagination, therefore, is a spontaneous process which occurs when an individual is doing nothing in particular, is not responding to any clearly identifiable stimulus and is relatively passive. All that really happens is that he experiences different sensory impressions in the absence of corresponding sensory stimulations in a random and disjointed manner.
He appears to ‘hear’ and ‘smell’ things, which otherwise form part of his daily experiences. This shows one more characteristic of imagination. It is actually the experiencing of earlier sensory experiences in the absence of the relevant stimuli. Imagination, therefore, is based on one’s past experiences.
The sensory experiences or impressions which occur in the absence of the relevant objects or stimuli are known as images. Any sensory experience having occurred once is capable of reappearing as an image. The face of a friend, the voice of one’s mother, the smell of a flower, a pain in the body, in fact anything can occur as an image. We may, therefore, call images shadow sensations or perceptions.
Individuals differ with regard to the clarity and intensity of the images that they can experience. It is also possible that some individuals have a stronger capacity to experience visual images, others to experience auditory images, and so on. Thus, people show different types of image-dominance. In fact, years ago Francis Galton developed a questionnaire-to measure such individual differences. Images have been classified into a number of types.
Most of our images belong to the category of memory images. This means that these images are the reappearances of some sensory experiences which have been experienced before. The voice of a friend, the face of your favorite film star, the smell of food you had once enjoyed eating, etc. belong to this category. Such memory images, though they are derived from original sensory experiences, are generally less clear and vivid compared to the original experiences.
These constitute another category of images. Though after-images are also based on sensory experiences, they are basically physiological in character and occur immediately after particular sensory experiences.
They are not revived from memory. A third category of images are called verbal image or abstract image. These, are symbolic in nature and are not purely sensory in character. They often tend to be abstract. Verbal images and abstract images are in many instances not dependent on memory or past sensory experience alone.
They are often original and creative. Poets and writers make extensive use of verbal and abstract images, and so do philosophers, mathematicians and scientists. Verbal and abstract images are usually more complex than memory images and involve a greater degree of perceptual organisation and the active participation of intelligence and even of personality.
They are more influenced by dynamic processes in the individual, particularly needs, motives etc. While memory images involve mainly a passive revival of past sensory experiences, abstract images are products of a more active process of psychological involvement and interaction.
Yet another type of images are known as eidetic images. These are very similar to memory images, the only difference being that these images are exactly identical in all details with the original sensory experience. Eidetic images are found more commonly among children than among adults. These images are almost photographic in nature. Another way of classifying Images is in terms of the particular sensory modality involved like auditory, visual, olfactory, etc.