Hermann Ebbinghaus (24 January 1850 – 26 February 1909) was a German psychologist. Today, he is mostly known for his work regarding learning and forgetting. He was the first to do experiments to explore how memory works. He first described the forgetting curve, the learning curve and the spacing effect. The Ebbinghaus illusion, which is named after him is related to the perception, not memory. His son was the philosopher Julius Ebbinghaus. 