Extreme retentiveness of memory, excessive memory activity, or unusual clarity of memory images.Hypermnesia occasionally occurs in normal individuals who are undergoing great stress pr who are faced with death; in mental prodigees and certain individuals who devote excessive time and effort to the cultivation of memory; and in patients suffering from certain mental disorders. A striking example of the first type is what has been called “panoramic memory,” the tendency to review one’s entire life, particularly while drowning. Menninger (1948) cites the following experience of a young man as he was sinking for the third time: “The course of those thoughts I can even now in great measure retrace . . . the event which had just taken place; the awkwardness which had produced it; the bustle it must have occasioned; the effect it would have on a most affectionate father; the manner in which he would disclose it to the rest of the family; and a thousand other circumstances minutely associated with home, were the first series of reflections that occurred. Then they took a wider range: our last cruise; a former voyage and shipwreck; my school, the progress I had made there, and the time I had misspent, and even all my boyish pursuits and adventures. Thus traveling downward, every past incident of my life seemed to glance across my recollection in retrograde succession; not, however, in mere outline, as you stated,but the picture filled up with every minute and collateral feature. In short, the whole period of my existence seemed to be traced before me in a kind of panoramic review, and each act of it seemed to be accompanied by a consciousness of right or wrong, or by some reflection on its cause or its consequences; indeed, many trifling events which had been long forgotten crowded into my imagination, and with a character of recent familiarity.”Psychologists who have made a special study of geniuses and prodigies report many cases of remarkable memory. Catharine M. Cox (1926) cites, among others, the fact that the German philosopher Fichte could repeat an entire sermon after hearing it once, that Racine could quote entire plays from memory, and that Chateaubriand learned the entire table of logarithms by heart. In the field of music, Mozart was able to write the entire Miserere of Allegri after hearing it played once; and in the field of politics, it is said that Themistocles could address twenty- one thousand Athenian citizens by name. See PRODIGY.As a pathological symptom, hypermnesia occurs most frequently in the manic phase of manic-depressive reaction, particularly in hypomania. It is also observed, though less often, in paranoid reactions and in states of catatonic excitement experienced by some schizophrenic patients. Typically, all these patients not only register and retain minute details of personal experiences, but recall them with striking vividness and clarity. The reaction is usually limited to specific situations in which the patient is emotionally involved. Menninger cites the following samples of the stream of conversation of a twenty-two-year-old manic girl who talked continuously in this vein for months:“From there we went over to Jane’s apartment, 4137 Broadway, telephone Maine 4521-W, second flight up—we went there and she wasn’t home, but I said we’d wait, because it was only 3:30—3:27, to be exact—I’m sure it was because I looked at Jane’s mantel clock—she has a clock that George got for her in Chicago—at a place on Michigan Avenue—let me see, I ought to remember the name of that store—oh Abt’s—that’s it—on Michigan Avenue near—well, anyway, it keeps wonderful time but this day it was slow—half an hour slow—and I couldn’t believe it was so early yet and so I called Central and asked the time and she wouldn’t tell me, but I remembered that Dixon’s always . . . are you listening to me Well, we stayed there until Jane came—about four o’clock— no, it was after four, because I saw Mr. Smelzer go to work, and Jane says he has to be there at five and always leaves at four. He works at the Post Office, you know . . See CIRCUMSTANTIALITY. Examples of the type quoted above indicate that the brain retains far more experience than is commonly recognized. It appears that little if anything is lost, once it has been registered, though as yet we do not know much about the registration process itself. This fact has been illustrated experimentally in two major ways. First, it has long been known that hypnotic suggestion can produce a state of hy- permnesia. Many hypnotists are able to induce their subjects to recall buried events from the past, recite poems learned in early childhood, or locate articles they have misplaced. Second, direct stimulation of certain regions of the brain itself has been found to resurrect long-forgotten events with the clarity of a film or tape recorder. A classic example is Penfield’s account (1954) of experiments performed during brain surgery on epileptic patients. The patients were conscious, since the brain does not contain nerve endings that register pain, and it was therefore possible to test the subject’s response to stimulation of various points in the cortex as a means of determining the proper site of the operation:“A young woman heard music when a certain point in the superior surface of the temporal cortex [on the side of the brain] was stimulated. She said she heard an orchestra playing a song. The same song was forced into her consciousness over and over again by restimulation at the same spot. It progressed from verse to chorus at what must have been the tempo of the orchestra when she heard it playing thus. She was quite sure each time that someone had turned on a gramophone in the operating room.“A South African who was being operated upon cried out in great surprise that he heard his cousins talking, and he explained that he seemed to be there laughing with them although he knew that he was really in the operating room in Montreal.”As Penfield remarked, “It is as though the cortex contained a continuous strip of cinematographic film, a strip that includes the waking record from childhood on.”