Memory

People have sought to understand the nature of memory since at least the time of the ancient Greek philosopher Plato, who is usually credited with the earliest serious discussion of it. He believed memory was like a blank slate on which accurate impressions of the world were made and preserved indefinitely. Plato distinguished two aspects of memory—the power to retain or keep information, and the power of recollection, or remembering information that is already present in memory. Plato's ideas still influence many contemporary psychological theories of memory contain these same beliefs.

During the Middle Ages, before the printing press, memory served as the vehicle through which history and knowledge were passed between people and generations. It seems having a good memory was greatly prized during the Middle Ages, and the improvement of memory skills was an important topic. A distinction was made between natural and artificial memory where natural memory was the memory abilities we were born with. They could not be trained and were thought to operate in a spontaneous, instinctive manner. On the other hand, artificial memory abilities were held to be trainable, and numerous systems were developed to improve them. As the printed word spread and the individual's memories became less essential in the transmission of knowledge the importance placed on memory by society apparently diminished. During the 1800s, educators also focused on training and exercising the memory. Memory was seen by many as being like a muscle that required exercise to remain fit. Thus memorization was thought to strengthen one's current memory system as well as future memorization skills, and rote memorization (memorizing information for no purpose other than to memorize it) was advocated for students. This view came under great criticism as the 1800s ended, and eventually the advocacy of rote memorization within the school system faded. Indeed, more recent research indicates that memorization for memorization's sake does not improve overall memory abilities in any observable way.

During the late 1800s the medical profession became interested in disorders of memory such as aphasia (a complete or partial impairment of the ability to understand or use words), and amnesia (generally, a partial or total loss of memory). The medical profession naturally focused on physiological and biological factors, and one of their most important findings was that aphasia was caused by lesions in the brain. This finding was of immense importance as it demonstrated for the first time that physiological and psychological functioning are connected.

Sigmund Freud, an Austrian physician who began his career in the 1890s, focused on psychological disorders that he felt were caused by memory disturbances. Freud felt mental illness occurs when unpleasant childhood memories are repressed, or kept from consciousness. His highly influential theory of psychoanalysis is in fact based on the concept that memories can be repressed, and he developed psychoanalytic therapy to uncover those memories and cure the patient.

The German psychologist, Hermann Ebbinghaus, carried out the first controlled experiments on memory in 1885, and in so doing set a pattern for modern experimental research on memory. Ebbinghaus developed many methods of studying memory that are still in use today. For example, he developed lists of nonsense syllables (one syllable groups of letters that have no meaning, e.g. "treb," "fug," or "duj"), that individuals would be asked to memorize. Ebbinghaus used nonsense syllables in an attempt to avoid the effects of previous learning, and associations the individual might have to meaningful words. Ebbinghaus would vary different aspects of the experiments to test different aspects of memory. For instance, he varied the lists by length to see how the number of syllables affected recall, and he would vary the amount of time between memorization and recall to see how the amount of time lapsed between learning and recall affected the amount of material recalled or forgotten.