Retrieval cues may be based on context-the setting or situation in which information is encoded and retrieved. Examples include a particular room, driving along a motorway, a certain group of people, a rainy day and so on. Clearly, in any real-life situation, the time between learning something and recalling it will be filled with all kinds of different events. This makes it very difficult to be sure that any forgetting which takes place is the result of decay rather than a consequence of the intervening events. Rasch B, Born J. About sleep's role in memory. Physiol Rev. 2013;93(2):681-766. doi:10.1152/physrev.00032.2012 Müller GE, Schumann F (1894) Experimentelle beiträge zur untersuchung des gedächtnisses. Zeitschrift für Psychologie 5: 81–190, 257–332.

Ebbinghaus function from 1880 is a type of double power function. A normal power function is described by the equation , where Q( t) is savings at time t and μ 1 and a 1 are parameters. The latter equation has been proposed by several authors to describe the time-course of forgetting (e.g., [ 1, 3, 4, 34]). The forgetting mechanism typically associated with a power function is a constant slowing down of the forgetting rate with time (cf. Ebbinghaus' account from 1880 mentioned above). Whereas this is certainly a viable mechanism of forgetting, it can be proven mathematically that (spurious) power functions may emerge from averaging over different subjects or items [ 35, 36]. This has also been shown in simulations considering a wide range of circumstances [ 37, 38]. As argued in the previous section, the forgetting curve (also) averages over items that have been learned to various degrees, due to their serial position. There are, therefore, several reasons to expect and consider the power function. Ammons RB, Farr RG, Bloch E, Neumann E, Dey M, et al. (1958) Long-term retention of perceptual-motor skills. Journal of Experimental Psychology 55: 318–328. pmid:13539312 Loftus, Geoffrey R. (1985). "Evaluating forgetting curves" (PDF). Journal of Experimental Psychology: Learning, Memory, and Cognition. 11 (2): 397–406. CiteSeerX 10.1.1.603.9808. doi: 10.1037/0278-7393.11.2.397. Archived (PDF) from the original on 2006-09-10. According to the trace decay theory of forgetting, the events between learning and recall have no affect whatsoever on recall. It is the length of time the information has to be retained that is important. The longer the time, the more the memory trace decays and as a consequence more information is forgotten. How to Use the Ebbinghaus Forgetting Curve with Spaced Learning What is the Ebbinghaus Forgetting Curve?There is very little direct support for decay theory as an explanation for the loss of information from short-term and long-term memory. One of the problems with decay theory is that it is more or less impossible to test it.

These two answers summaries the main theories of forgetting developed by psychologists. The first answer is more likely to be applied to forgetting in short-term memory, the second to forgetting in long term memory. Darby KP, Sloutsky VM. The cost of learning: Interference effects in memory development. J Exp Psychol. 2015;144(2):410–431. doi:10.1037/xge0000051 So the primacy effect reflects items that are available for recall from long-term memory. However, words in the middle of the list used to be in short term memory until they were pushed out – or displaced by the words at the end of the list. EvaluationHis premise was that each repetition in learning increases the optimum interval before the next repetition is needed (for near-perfect retention, initial repetitions may need to be made within days, but later they can be made after years). He discovered that information is easier to recall when it's built upon things you already know, and the forgetting curve was flattened by every repetition. It appeared that by applying frequent training in learning, the information was solidified by repeated recalling. However, when the material is being repeated at strategically spaced intervals, the brain reconstructs the memory and strengthens it in the process. These specific time intervals between multiple learning sessions are essential. They allow the brain to recover between repetitions and consolidate the learning. Munce takes Telly to an airport and the dilapidated hangar of Quest Airlines, where he introduces her to an agent of "them". He tells the agent that it's over and to stop the experiment, because it will only cause more harm. But the agent replies that it's not over. He reveals to Telly that she has been a part of an experiment to test whether the bonds between mother and child can be diminished. In her case, her memories could not be fully erased. Retrieval failure is where the information is in long-term memory, but cannot be accessed. Such information is said to be available (i.e. it is still stored) but not accessible (i.e. it cannot be retrieved). It cannot be accessed because the retrieval cues are not present. The previous accounts of forgetting have focused primarily on psychological evidence, but memory also relies on biological processes. For example, we can define a memory trace as:

While some aspects that contribute to the speed of forgetting cannot be changed, Ebbinghaus proposed the use of two methods when we purposefully acquire new skills or knowledge: mnemonic techniques and repetitions. Implementing these strategies can help us overcome the forgetting curve. Mnemonic techniques The Forgotten is a 2004 American science fiction psychological thriller film directed by Joseph Ruben and starring Julianne Moore, Dominic West, Gary Sinise, Alfre Woodard, Linus Roache, and Anthony Edwards. The film's plot revolves around a woman who lost her son in a plane crash 14 months earlier, only to wake up one morning and be told that she never had a son. All of her memories are intact, but with no physical evidence that contradicts the claims of her husband and her psychiatrist, and she sets out in search for solid evidence of her son's existence. Summarizing, Ebbinghaus' data fit his own equations and the power function best. The AIC indicates that on average the MCM equation (or summed exponential function) is on average better than all equations considered thus far, where the difference with the power function is 1.5. The difference with Ebbinghaus' own equations is only 0.5 but this is partially because his own data have an exceptionally good fit on his own equations, with a very low AIC of about -30.5 (and an extremely high 99.8% variance explained). It is likely, however, that Ebbinghaus actively searched for an equation that achieves such an exceptional fit, which in his eyes was no more than a 'summary' of the forgetting curve (see citation above). This also explains why he has no problems substituting a 'logarithmic' equations for the earlier 'power' equation: it shows a slightly better fit. Interference theory states that forgetting occurs because memories interfere with and disrupt one another, in other words forgetting occurs because of interference from other memories (Baddeley, 1999). There are two ways in which interference can cause forgetting: It is hard to overestimate the importance of Hermann Ebbinghaus' contribution to experimental psychology. Influenced by the work of the German philosopher Herbart, he was the first to carry out a series of rigorous experiments on the shape of forgetting, which he completed in 1880. The experiment itself was preceded by a period in which he tried out a variety of materials and methods. After having tested himself with tones, numbers, and poem stanzas, he decided that none of these served his purposes. Tones were too cumbersome to handle and too difficult to reproduce for him, he did not find digits zero to nine suitable as basic units for the long-running experiments he envisioned, and the poem fragments he tried to learn (from Byron’s Don Juan) were deemed too variable in the meanings they evoked and therefore likely to cause measurement error [ 8] (p. 14–17). He, therefore, introduced nonsense syllables, which had more uniform characteristics than existing words or other verbal material. In his later experiments on learning, however, he did verify his results with the Don Juan verses, confirming both his main results on learning and his intuition that the latter stimuli did indeed yield much more variance in the data [ 9]. Since his introduction of nonsense syllables, a large number of experiments in experimental psychology has been based on highly controlled, artificial stimuli.There is evidence that the consolidation process is impaired if there is damage to the hippocampus (a region of the brain). In 1953, HM had brain surgery to treat his epilepsy, which had become extremely severe.