I'm searching for research answering or giving any form of insight to this question:
How long time does it take a person to relearn something (any type of learning) when relearning happens x, x+1, x+2...x+n years after initial learning.

I've found some research made by Ebbinghaus, but relearning only happens after 24 hours - the variable in his research is repetetion times (and not time between initial learning and relearning) which isn't what I'm looking for either.

To be clear about what I'm trying to find out (the practical part): I'm trying to figure out the effectiveness of students studying a subject in college, and how long time they will need to relearn/review that subject, if they relearn it 5, 10 or maybe 15 years later after the initial learning in college.


Ebbinghaus, H. (1885). Memory: A Contribution to Experimental Psychology. (H.A. Ruger & C.E. Bussenius, Trans.). New York: Teachers College, Columbia University.