Hermann Ebbinghaus (24 January 1850 – 26 February 1909) was a German psychologist who pioneered the experimental study of memory.

After beginning his studies at the University of Berlin, he founded the third psychological testing lab in Germany (third to Wilhelm Wundt and Georg Elias Müller).

Untersuchungen zur experimentellen Psychologie, later published in English under the title Memory: A Contribution to Experimental Psychology[3] — he was made a professor at the University of Berlin, most likely in recognition of this publication.

While the specifics on how these mental abilities were measured have been lost, the successes achieved by the commission laid the groundwork for future intelligence testing.

In 1902, Ebbinghaus published his next piece of writing entitled Die Grundzüge der Psychologie (Fundamentals of Psychology).

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.

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).

Then, to the regular sound of a metronome, and with the same voice inflection, he would read out the syllables, and attempt to recall them at the end of the procedure.

First, Ebbinghaus made a set of 2,300 three letter syllables to measure mental associations that helped him find that memory is orderly.

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.

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.

Psychologist William James called the studies "heroic" and said that they were "the single most brilliant investigation in the history of psychology".

This illusion is now used extensively in cognitive psychology research, to help map perception pathways in the human brain.

In addition to pioneering experimental psychology, Ebbinghaus was also a strong defender of this direction of the new science, as is illustrated by his public dispute with University of Berlin colleague, Wilhelm Dilthey.

The debate at the time had been primarily whether psychology should aim to explain or understand the mind and whether it belonged to the natural or human sciences.

Charlotte Bühler echoed his words some forty years later, stating that people like Ebbinghaus "buried the old psychology in the 1890s".

Ebbinghaus explained his scathing review by saying that he could not believe that Dilthey was advocating the status quo of structuralists like Wilhelm Wundt and Titchener and attempting to stifle psychology's progress.

The one influence that has always been cited as having inspired Ebbinghaus was Gustav Fechner's two-volume Elemente der Psychophysik.

This inspiration is also evident in that Ebbinghaus dedicated his second work Principles of Psychology to Fechner, signing it "I owe everything to you.