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50 Years of Retention Data

Page history last edited by Regina Claypool-Frey 14 years, 1 month ago

Fifty Years of Retention Data -- Vocabulary Retention

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Subj: 50 years of retention data

Date: 08/03/98

To: SClistserv@

CC: guybruce@

This weekend I came across a most amazing research study. A researcher named H.P. Bahrick (1984) reported retention data from the same subjects over a 50-year time frame. 50 years!

These were students who had learned Spanish-English vocabulary. Bahrick tested them at the following intervals:

1 yr 2 mo,

3 yr 2 mo,

5 yr 9 mo,

9 yr 6 mo,

14 yr 7 mo,

25 yr 1 mo,

34 yr 7 mo,

49 yr 8 mo.

Bahrick did not have true frequency data up the left on his charts. Instead, he plotted test scores. But, still -- 50 years.

The data show some drop off across the first three years. The people with the lowest test scores dropped down the most. From 3 years to the 25th year the subjects showed almost no drop off. In fact, they went up slightly. However, there followed a final drop-off between the 34th year and the 49th. As Anderson (1995) relates, "Bahrick (personal communication) suspects that this final dropoff is probably related to physiological deterioration in old age."


Anderson, J.R. (1995). Cognitive psychology and its implications. Fourth Edition. New York: W.H. Freeman and Company. LOC#: BF311.A5895 1995.

Bahrick, H.P. (1984). Semantic memory in permastore: Fifty years of memory for Spanish learned in school. Journal of Experimental Psychology: General, 113, 1-24.

-- John Eshleman

P.S. Interestingly enough, whereas the axes up the left of Bahrick's charts have equal intervals, the axes across the bottom are logarithmic. The label for the horizontal axes read "Log (Time + 1) in years." The distance from 3 to 5 years appears about the same as that for 14 to 25 years. So, Bahrick's charts seem kind of like the reverse of Standard Celeration Charts: Equal add up the left, multiply-divide across bottom!


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