The Forgetting

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Displacement theory provides a very simple explanation of forgetting. Because of its limited capacity, suggested by Miller to be 7+/- 2 items, STM can only hold small amounts of information. Baddeley, A. D., & Logie, R. H. (1999). Working memory: The multiple-component model. In A. Miyake & P. Shah (Eds.), Models of working memory (pp. 28±61). Cambridge, UK: Cambridge University Press. Forgetting information from short term memory (STM) can be explained using the theories of trace decay and displacement. We need to elaborate on the choice of these time intervals as there is some confusion about the exact length of the shorter retention intervals used by Ebbinghaus. He mentions both 15 min (in 1880 [ 8]) and 19 min (in 1885 [ 9]) for the shortest interval, and 63 min and 8.75 hours (525 min) for the longer intervals. He also states that relearning took place “after about one third of an hour, after 1 hour, after 9 hours, one day, two days, six days, or 31 days.” ([ 20], p. 66). Heller et al. [ 21] followed the latter intervals, using 20 min, 60 min and 9 hours, etc. We have also used these, given that this seems to have been the intended lengths of Ebbinghaus’ retention intervals. The deviations these values by Ebbinghaus are based on corrections after the experiment.

There are a number of methodological problems confronting researchers trying to investigate the trace decay theory. One of the major problems is controlling for the events that occur between learning and recall. Displacement theory provided a good account of how forgetting might take place in Atkinson & Shiffrin’s (1968) model of short-term memory. However, it became clear that the short-term memory store is much more complex than proposed in Atkinson and Shiffrin’s model (re: working memory).

Introduction

Ebbinghaus’ experimental method, like that of many of his peers, consisted of conducting a series of extensive tests on himself. He created hundreds of three-letter words, or “nonsense syllables” as he called them, like “wid”, “zof”, and “qax.” Anderson JR, Schooler LJ (1991) Reflections of the environment in memory. Psychological Science 2: 396–408.

Ebbinghaus was the first psychologist who systematically studied memory and learning. He recorded his findings mathematically in an attempt to discover patterns of forgetting and memory retention.

Discussion

In general, his memory for events before the surgery remains intact, but he does have some memory loss for events which occurred in the two years leading up to surgery. Fig 6. Serial position for correct relearning scores for each retention interval and for the average of all retention intervals (see text for an explanation). This paper describes a replication of one of the most important early experiments in psychology, namely Ebbinghaus' classic experiment on forgetting from 1880 and 1885. We replicated the experiment that yielded the famous forgetting curve describing forgetting over intervals ranging from 20 minutes to 31 days. Ebbinghaus' goal was to find the lawful relation between retention and time-since-learning. This is why he fitted the data to two different functions (a power function, 1880, and a logarithmic function, 1885), as have many theorists since (e.g., [ 1, 2– 4]). This papers also includes an analysis—including one with a new model—of the shape of the Ebbinghaus' forgetting curve and its replications. Do the replicated forgetting curves have the same shape, or must we conclude that Ebbinghaus' forgetting curve was idiosyncratic and that quite different shapes may occur? Rasch B, Büchel C, Gais S, Born J (2007) Odor cues during slow-wave sleep prompt declarative memory consolidation. Science 315: 1426–1429. pmid:17347444 de Bot K, Martens V, Stoessel S (2004) Finding residual lexical knowledge: The 'Savings' approach to testing vocabulary. International Journal of Bilingualism 8: 373–382.