Ebbinghaus was determined to show that higher mental processes could actually be studied using
experimentation, which was in opposition to the popularly held thought of the time. To control for most potentially confounding variables, Ebbinghaus wanted to use simple acoustic encoding and
maintenance rehearsal for which a list of words could have been used. As
learning would be affected by prior knowledge and understanding, he needed something that could be easily memorized but which had no prior cognitive associations. Easily formable associations with regular words would interfere with his results, so he used items that would later be called "
nonsense syllables" (also known as the
CVC trigram). A nonsense syllable is a
consonant-
vowel-consonant combination, where the consonant does not repeat and the syllable does not have prior meaning. BOL (sounds like "Ball") and DOT (already a word) would then not be allowed. However, syllables such as DAX, BOK, and YAT would all be acceptable (though Ebbinghaus left no examples). After eliminating the meaning-laden syllables, Ebbinghaus ended up with 2,300 resultant syllables. It appears that Ebbinghaus recognized this, and only referred to the strings of syllables as "nonsense" in that the syllables might be less likely to have a specific meaning and he should make no attempt to make associations with them for easier retrieval.
Contributions In 1885, he published his groundbreaking
Über das Gedächtnis ("On Memory", later translated to English as
Memory. A Contribution to Experimental Psychology) in which he described experiments he conducted on himself to describe the processes of
learning and
forgetting. Ebbinghaus made several findings that are still relevant and supported to this day. First, Ebbinghaus made a set of 2,300 three letter syllables to measure mental associations that helped him find that memory is orderly . Second, and arguably his most famous finding, was the
forgetting curve. The forgetting curve describes the
exponential loss of information that one has learned. The sharpest decline occurs in the first twenty minutes and the decay is significant through the first hour. The curve levels off after about one day. The
learning curve described by Ebbinghaus refers to how fast one learns information. The sharpest increase occurs after the first try and then gradually evens out, meaning that less and less new information is retained after each repetition. Like the forgetting curve, the learning curve is exponential. Ebbinghaus had also documented the
serial position effect, which describes how the position of an item affects recall. The two main concepts in the serial position effect are recency and primacy. The recency effect describes the increased recall of the most recent information because it is still in the short-term memory. The primacy effect causes better memory of the first items in a list due to increased rehearsal and commitment to long-term memory. Another important discovery is that of savings. This refers to the amount of information retained in the
subconscious even after this information cannot be consciously accessed. Ebbinghaus would memorize a list of items until perfect
recall and then would not access the list until he could no longer recall any of its items. He then would relearn the list, and compare the new learning curve to the learning curve of his previous memorization of the list. The second list was generally memorized faster, and this difference between the two learning curves is what Ebbinghaus called "savings". Ebbinghaus also described the difference between involuntary and voluntary memory, the former occurring "with apparent spontaneity and without any act of the will" and the latter being brought "into consciousness by an exertion of the will". Prior to Ebbinghaus, most contributions to the study of memory were undertaken by philosophers and centered on observational description and speculation. For example,
Immanuel Kant simply described recognition and its components. On the other hand,
Sir Francis Bacon claimed that the simple observation of the rote recollection of a previously learned list wasn't useful to understanding memory. This dichotomy between descriptive and experimental study of memory would resonate later in Ebbinghaus's life, particularly in his public argument with former colleague
Wilhelm Dilthey. However, more than a century before Ebbinghaus,
Johann Andreas Segner invented the "Segner-wheel" and would use both by seeing how fast a wheel with a hot
coal attached had to move for the red ember circle from the coal to appear complete (see
iconic memory). He proceeded to view the length of the after images. Ebbinghaus's effect on memory research was almost immediate. With very few works published on memory in the previous two millennia, Ebbinghaus's works spurred memory research in the United States in the 1890s, with 32 papers published in 1894 alone. This research was coupled with the growing development of mechanized
mnemometers (an outdated mechanical device used for presenting a series of stimuli to be memorized). The reaction to his work in his day was mostly positive. Psychologist
William James called the studies "heroic" and said that they were "the single most brilliant investigation in the history of psychology".
Edward B. Titchener also mentioned that the studies were the greatest undertaking in the topic of memory since
Aristotle. == Research on cramming ==