Visual memory is part of memory preserving some characteristics of our senses pertaining to visual experience. We are able to place in memory information that resembles objects, places, animals or people in sort of a mental image. Some authors refer to this experience as an "our mind's eye" through which we can retrieve from our memory a mental image of the original object, place, animal or person. The first person to give serious consideration to visual imagery was Sir Francis Galton (1822-1911) in the field of individual differences. In his research Galton asked his subjects to describe and rate their visual images on vividness. His research showed a wide range of clarity ranging from vivid mental images to none among his test subjects (Galton 1883).
Since this way of judging a mental image has very little scientific objectivity, psychologist have devised more objective ways of evaluating mental images based on how much information can be retrieved from mental images. Over all there are not any conclusive data that would show a benefit from training with visual mnemonics (Baddeley, 1976). The following are three examples of visual learning that psychologists have described.
Eidetic imagery is perhaps the most accurate and the only kind that produces a visual memory that is like looking at an actual picture. Lake, Haber and Haber produced a study in which they presented a subject with an image for 30 s. After removing the image the subjects ware asked whether they could "see" (remember) anything. In a study of elementary school children they presented them with an illustration of Alice in Wonderland. After removing it some children were able to describe with vivid accuracy the image they had seen.(Haber 1969)
Eidetic imagery seems to be stronger in children since the adult subjects did not report as many details. Koslyn contributes this difference to the lack of verbal and conceptual systems in children when compared to adult models (Koslyn 1980, 1984)
There is also no supportive evidence of photographic memory. This phenomenon is usually contributed to some people exceptionally skilled in mental organization. ===Iconic memory=== Iconic Memory was coined by George Sperling (1960) (for more detail on Sperling's research check Sensory memory)
Visual persistence is the apparent persistence of a visual stimulus beyond its physical duration. The phenomenon usually includes the subjective feeling that you can 'look around' the scene and that it 'fades away' rather than 'switches off'. Your eye itself does not continue to send messages into the visual system after the image has been processed (with the exception of retinal afterimages), rather, the percept is a mental event, one that reflects visual persistence... since any persistence of information beyond the physical duration is memory... the process of visual perception must begin with visual sensory memory (also known as iconic memory (Neisser, 1967).
Spatial memory could also be a subcategory of visual memory since it relies on a mental map. 'The Neural Basis of Spatial Memory is a fascinating web site focusing on the physiological aspects of spatial memory.
Gleitman, H.(1991)Psychology, 7, 275-278.