The laws of memory: does forgetting follow a regular quantitative curve, and are learning and retention lawful?

Hermann Ebbinghaus, answered from the texts and cited to the page.

The position in brief

Forgetting is not capricious; it obeys a law. When I learned my lists and tested how much remained after an hour, a day, a week, I found always the same course: the greater part of what is learned is lost swiftly, in the first hours, and then the remainder fades ever more slowly, so that what survives a few days survives long.1 I measured retention not by what I could consciously recite — much persists that cannot be recited — but by the savings in relearning, the repetitions spared because a trace, however faint, remained.2

And I found further laws: that repetitions beyond bare mastery, an over-learning, fix a list more firmly; that a long list costs far more than its length would suggest; and — most useful of all — that repetitions spread out over several days accomplish far more than the same number crammed into one sitting. These are not impressions but measured regularities, curves one can draw and predict from. Memory, studied exactly, is as orderly as any process in nature.34

Sources

  1. II III IV So much of the series learned was retained that The amount forgotten No. After X hours in relearning a saving of Q % of the time of original learning was made P.E.m was thus equivalent to v % of the original in terms of time of learning X= Q= v= 1 0.33 58.2 1 41.8 2 1. 44.2 1 55.8 3 8.8 35.8 1 64.2 4 24. 33.7' 1.2 66.31 5 48. 27.8 1.4 72.21 6 6x24 25.4 1.3 74.6 7 31x24 21.1 0.8 78.9 Section 29.
    Memory A Contribution to Experimental Psychology
  2. The effect of the repetitions is at first approxi- Retention as a Function of Repeated Learning 89 mately constant, the saving in work which results from these repetitions increases accordingly for a while proportional to their number.
    Memory A Contribution to Experimental Psychology
  3. So here, even more than elsewhere, I am unable to affirm that the simple conformity to law approximately realised in the results so far obtained would Retention as a Function of Repeated Learning 87 stand the test of repetition or wider extension of research. I content myself by calling attention to it without emphasis. Section 34.
    Memory A Contribution to Experimental Psychology
  4. The material to be learned has been presented in pairs, and the number of pairs has been counted of which one element causes the mental reproduction of the other. By all these methods psychologists have definitely secured many rules which had been derived from earlier, less reliable experiences. Many new facts have also been discovered. Let us give a brief account of the results of this work.
    Psychology An Elementary Text-book

Where the argument is made

  • Memory (1913 — the forgetting curve, the savings method, the effects of repetition and over-learning, the distribution of practice / spacing effect, the serial-position and list-length effects)

How the argument was received

Ebbinghaus's quantitative laws of memory are among the most durable findings in psychology. The forgetting curve (rapid initial loss, then a slow decline), the savings method's demonstration of retention below recall, the value of over-learning, the serial-position and list-length effects, and above all the spacing (distribution-of- practice) effect have been replicated countless times and are cornerstones of the modern science of learning — the spacing effect and the related testing effect now underpin evidence-based study and educational technology (spaced-repetition systems). The one live technical question is the exact mathematical form of the forgetting function (logarithmic, power, exponential), refined over the decades; the phenomena themselves are settled and Ebbinghaus's.