In simple terms, a memory
which acts as though the person has taken photographs of everything he's ever seen and can refer back to them at will. A person with a photographic memory has total recall
at any moment of any of these images (including such things as individual pages from books). I am unsure of how wide spread this phenomenon
is. Perhaps no-one has it, perhaps only a few.
One belief is that the photographic memory operates from the right brain instead of the left. Here is quote from a page about child geniuses (www.ycsi.net/users/ipainc/rapi-rtbrain.html):
"By age six the left brain is dominant, but before age six there is a window of opportunity where the right brain is dominant. Shichida says that presenting large amounts of information at a fast pace to infants, toddlers and preschoolers stimulates the right brain and can activate photographic memory."
Of course, there is also beliefs that the photographic memory doesn't exist. Here is a quote from a page on the MadSci Network (www.madsci.org/posts/archives/aug97/866819368.Ns.r.html):
"Scientists who study memory phenomena generally believe that eidetic
memory (more popularly known as "photographic memory") does not exist.
Early experiments on eidetic memory were intriguing, but could not be
"People do show extraordinary memory performance in certain circumstances."
"Impressive as these feats are, scientists attribute them to
specialized ways of thinking about the information, not to any kind of
enhanced visual memory."
Another theory? Well, there are those who believe that humans retain the memory of everything in their life, but the recall function of the memory doesn't work to it's full capacity. This is why hypnosis can draw forth memories previously forgotten. Perhaps people with photographic memories are the same as the rest of us, but their recall function works perfectly. If this is true, then could it be that with the right conditioning, all of us can improve our recall function and therefore our "memory", although never to the point of the person with photographic skill.
If it pleases you, replace all of the "photographic memory" phrases in this write-up with "eidetic memory/eidetic imagery/ eidetic recall". The scholarly term for photographic memory has varied, in the very limited literature, between eidetic and eidectic. These days the term "photographic memory" gets bandied around a lot without the users meaning eidetic memory. For example, here's a disclaimer from photomind.com on their use of the words "photographic memory":
Photographic memory is merely a term used to describe the ability to recall images in the mind in great detail. The word photographic in the Second College Edition: The American Heritage Dictionary (1991), indicates the validity of my usage in the sense divisions 3 and 4 for the adjective: 3. Resembling a photograph, esp. representing or simulating something with great accuracy and fidelity of detail. 4. Capable of forming accurate and lasting impressions: a photographic memory.
The term photographic memory should not be confused with eidetic imagery or recall which is the ability to recall in such detail as to look at a written page and recite every word verbatim , both backward and forward. However what you are about to learn is similar in that you will be able to recite a long list of items backward, forward and in any other order.
I recommend that you read other books on the subject of memory or mnemonics in order to satisfy your own learning needs."
This does not mean everyone uses the term without meaning eidetic memory. There are websites out there which deal with training the mind towards a true photographic memory. One that I found through www.google.com is http://www.crosswinds.net/~ufie/lectures/7.html (I have been informed that this url no longer exists)
This should give you an allround overview of what a photographic memory is. To find out more, see eidetic memory or use an internet search engine.