Re: what is the difference between eidetic memory and photographic memory?

The two phrases "photographic memory" and "eidetic imagery" are used interchangeably. Eidetic imagery is "marked by or involving extraordinarily accurate and vivid recall especially of visual images", according to Webster's dictionary. Two nice discussoions are available online: http://www.slc.edu/~ebj/minds/student_pages/sally-jane/ and http://serendip.brynmawr.edu/bb/neuro/neuro00/web2/Arnaudo.html. There is some thought that auditory memory may function in the same manner in some people - sort of a 'tape-recorder memory'. J A Gengerelli performed repeated experiments involving eidetic imagery, originally performed in 1928-29 on two girls, ages 11 and 15 years, in 1974 on the same two persons. It was found that minor changes (perhaps unreliable) had occurred in the precision of eidetic projection (or memory), and that both women retained their ability to project a seen circle onto a target square and compare the two for "goodness of fit." (Eidetic imagery in two subjects after 46 years. Gengerelli JA.J Gen Psychol. 1976 Oct;95(2d Half):219-25.) So this type of memory appears to be long-lasting.