Often, even after years, mental states once present in consciousness return to it with apparent spontaneity and without any act of the will; that is, they are reproduced involuntarily.

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. After eliminating the meaning-laden syllables Ebbinghaus ended up with 2300 resultant syllables. At the age of 17 (1867) he began attending the University of Bonn where he had planned to study history and philology.

Hermann Ebbinghaus (January 24 1850 — February 26 1909) was a German psychologist who pioneered the experimental study of memory and is known for his discovery of the forgetting curve and the spacing effect. He was also the first person to describe the learning curve.