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'''Decay theory''' proposes that [[memory]] fades due to the mere passage of time. [[Information]] is therefore less available for later retrieval as time passes and memory, as well as memory strength, wears away.<ref name="emtwo"> Berman, M.G. (2009) In Search of Decay in Verbal Short Term Memory [Electronic Version]. Journal of Experimental Psychology: Learning, Memory, and Cognition, 35(2), pp. 317-333. Retrieved March 6, 2010</ref> When we [[learn]] something new, a [[neurochemical]] “memory trace” is created. However, over time this trace slowly disintegrates. Actively [[memory rehearsal|rehearsing]] information is believed to be a major factor counteracting this temporal decline. <ref name="emfive">Oberauer, K., & Lewandowsky, S. (2008). Forgetting in immediate serial recall: decay, temporal distinctiveness, or interference? [Electronic version]. Psychology review, 115(3), pp. 544-576. Retrieved March 6, 2010.</ref> It is widely believed that [[neurons]] die off gradually as we age, yet some older memories can be stronger than most recent memories. Thus, decay theory mostly affects the [[short-term memory]] system, meaning that older memories (in [[long-term memory]]) are often more resistant to shocks or physical attacks on the [[brain]]. It is also thought that the passage of time alone cannot cause [[forgetting]], and that Decay Theory must also take into account some processes that occur as more time passes.<ref name="emtwo" />
==History==
The term decay theory was first coined by [[Edward Thorndike]] in his book “The Psychology of Learning” in 1914<ref name="kevone"> E. L. Thorndike, The psychology of learning, N. Y., Teachers College, 1914, p. 4.</ref>. This simply states that if a person does not access and use the memory representation they have formed the memory trace will fade or decay over time. This theory was based on the early memory work by [[Hermann Ebbinghaus]] in the late 1800s<ref name="kevtwo"> Ebbinghaus H. 1885/1913. Memory. A Contribution to Experimental Psychology. New York: Teachers College/Columbia Univ. (Engl. ed.)</ref>. The decay theory proposed by Thorndike was heavily criticized by McGouchMcGeoch and his interference theory <ref name="kevthree"> McGeoch, J. (1932) Forgetting and the Law of Disuse [Electronic Version]. Psychology Review, 39, pp. 352-370. Retrieved March 6, 2010</ref>. This led to the abandoning of the decay theory, until the late 1950s when studies by John Brown and the Petersons showed evidence of time based decay by filling the retention period by counting backwards in threes from a given number. This led to what is known as the [[Interference theory#Proactive interference|Brown-Peterson Paradigm]]<ref name="kevfour"> Brown, J. Some tests of the decay theory of immediate memory. Quarterly Journal of Experimental Psychology, 1958, 10, 12-21.</ref> <ref name"kevfive"> Peterson, L. R., & Peterson, M. J. Shortterm retention of individual verbal items. Journal of Experimental Psychology, 1959, 58, 193-198.</ref>. The theory was again challenged, this time a paper by Keppel and Underwood who attributed the findings to [[Interference theory#Proactive interference|proactive interference]]<ref name="kevsix"> Keppel, G., & Underwood, B. J. Proactive inhibition in short-term retention of single items. Journal of Verbal Learning and Verbal Behavior, 1962, 1, 153-161.</ref>. Studies in the 1970s by Reitman<ref name="kevseven"> Reitman J. S. Mechanisms of forgetting in short term memory. Cognitive Psychology. (1971, 1974)2, 185-195.</ref> <ref name="keveight> Reitman J. S. Without surreptitious rehearsal, information in short term memory decays. Journal of Verbal Learning and Shiffrin(1973)Verbal Behaviour. 1974, 13, 365-377.</ref> trytried reviving the decay theory by accounting for certain confounds criticized by Keppel and Underwood (1962) as well as Crowder (1967). Roediger (1977) quickly found problems with these studies and their methods <ref name="kevnine"> Roediger HL, Knight JL, Kantowitz BH. Harris1977. Inferring decay in short-term-memory—the issue of capacity. Mem. Cogn. 5(19522):167–76.</ref>. Harris made an attempt to make a case for decay theory by using tones instead of word lists and his results are congruent making a case for decay theory <ref name="kevten"> Harris, D. J., Pitch Discrimination. Journal of the Acoustical Society of America. Vol 24,1952, 750-755.</ref>. In addition, McKone (1995, 1998) used implicit memory tasks as opposed to explicit tasks to address the confound problems. They provided evidence for decay theory, however, the results also interacted with interference effects <ref name"kevelev"> McKone E. 1995. Short-term implicit memory for words and non-words. J. Exp. Psychol.: Learn. Mem. Cogn. 21(5):1108–26.</ref> <ref name="kevtwel"> McKone E. 1998. The decay of short-term implicit memory: unpacking lag. Mem. Cogn. 26(6):1173–86.</ref>. One of the biggest criticisms of decay theory is that it can’t be explained as a mechanism and that is the direction that the research is headed.
==Inconsistencies==
[[Image:decaycorrect.jpg|thumb|right|alt=Graph of recall probability over number of intervening items, accounting for time, if Decay Theory accounts for forgetting.|Recall probability over number of intervening items, accounting for time, if decay theory accounts for forgetting.]]
[[Image:interferencecorrect.jpg|thumb|right|alt=Graph of recall probability over number of intervening items, accounting for time, if Interference Theory accounts for forgetting.|Recall probability over number of intervening items, accounting for time, if ''[[interference theory]]'' accounts for forgetting.]]
Researchers disagree about whether memories fade as a function of the mere passage of time (as in decay theory) or as a function of interfering succeeding events (as in [[interference theory]])<ref name="emone">Lewandowsky, S., & Oberauer, K. (2009). No evidence for temporal decay in working memory [Electronic version]. Journal of experimental psychology: Learning, memory, and cognition, 35(6), pp. 1545-1551. Retrieved March 4, 2010.</ref>. Often, evidence tends to favour interference related decay over temporal decay <ref name="emtwo" />, yet this varies depending on the specific memory system taken into account.
===Short-Term Memory===
Within the [[short-term memory]] system, evidence favours an interference theory of forgetting, based on various researchers’ manipulation of the amount of time between a participant’s retention and recall stages finding little to no effect on how many items they are able to remember.<ref name="emone" /> Looking solely at verbal short-term memory within studies that control against participants’ use of rehearsal processes, a very small temporal decay effect coupled with a much larger interference decay effect can be found.<ref name="emtwo" /> No evidence for temporal decay in verbal short-term memory has been found in recent studies of serial recall tasks.<ref name="emtwo" /> Regarding the word-length effect in short-term memory, which states that longer word lists are harder to recall than short word lists, researchers argue that interference plays a larger role due to articulation duration being confounded with other word characteristics3characteristics.<ref name="emthree">Lewandowsky, S., & Oberauer, K. (2008). The word-length effect provides no evidence for decay in short-term memory [Electronic version]. Psychonomic bulletin and review, 15(5), pp. 875-888. Retrieved March 4, 2010.</ref>
===Working Memory===
Both theories are equally argued in [[working memory]]. One situation in which this shows considerable debate is within the [[memory span|complex-span task]] of working memory, whereas a complex task is alternated with the encoding of to-be-remembered items1items.<ref name="emone" /> It is either argued that the amount of time taken to perform this task or the amount of interference this task involves cause decay. <ref name="emone" /> A [[working memory#Time-based resource sharing model|time-based resource-sharing model]] has also been proposed, stating that temporal decay occurs once attention is switched away from whatever information is to be remembered, and occupied by processing of the information4information.<ref name="emfour">Portrat, S., Barrouillet, P., & Camos, V. (2008). Time-related decay or interference-based forgetting in working memory [Electronic version]. Journal of experimental psychology: learning, memory, cognition, 34(6), pp. 1561-1564. Retrieved March 6, 2010.</ref> This theory gives more credit to the active rehearsal of information, as refreshing items to be remembered focuses [[attention]] back on the information to be remembered in order for it to be better processed and stored in memory4memory.<ref name="emfour" /> As processing and maintenance are both crucial components of working memory, both of these processes need to be taken into account when determining which [[forgetting#Theories of forgetting|theory of forgetting]] is most valid. Research also suggests that information or an event’s [[salience (neuroscience)|salience]], or importance, may play a key role6role.<ref name="emsix">Buhusi, C.V., & Meck, W.H. (2006). Interval time with gaps and distractors: Evaluation of the switch, and time-sharing hypothesis [Electronic version]. Journal of experimental psychology: Animal behavior processes, 32(3), pp. 329-338. Retrieved March 6, 2010.</ref> Working memory may decay in proportion to information or an event’s salience6salience.<ref name="emsix" /> This means that if something is more meaningful to an individual, that individual may be less likely to forget it quickly.
===System Interaction===
These inconsistencies may be found due to the difficulty with conducting experiments that focus solely on the passage of time as a cause of decay, ruling out alternative explainations2explanations.<ref name="emtwo" /> However, a close look at the literature regarding decay theory will reveal inconsistencies across several studies and researchers, making it difficult to pinpoint precisely which indeed plays the larger role within the various systems of memory. It could be argued that both temporal decay and interference play an equally important role in forgetting, along with [[repressed memory|motivated forgetting]] and retrieval failure theory.
==Future Directions of Decay Theory==
Revisions in Decay Theory are being made in research today. The theory is simple and intuitive, but also problematic. Decay theory has long been rejected as a mechanism of long term forgetting. <ref> McGeoch,name="kevthree" J. (1932) Forgetting and the Law of Disuse [Electronic Version]. Psychology Review, 39, pp. 352-370. Retrieved March 6, 2010</ref>. Now, its place in short term forgetting is being questioned. The simplicity of the theory works against it in that supporting evidence always leaves room for alternative explanations. Researchers have had much difficulty creating experiments that can pinpoint decay as a definitive mechanism of forgetting. Current studies have always been limited in their abilities to establish decay due to confounding evidence such as attention effects or the operation of interference.<ref name="emtwo" />
===Hybrid Theories===
==References==
{{reflist}}
<references/>
1 Lewandowsky, S., & Oberauer, K. (2009). No evidence for temporal decay in working memory [Electronic version]. Journal of experimental psychology: Learning, memory, and cognition, 35(6), pp. 1545-1551. Retrieved March 4, 2010.
2 Berman, M.G., Jonides, J., & Lewis, R.L. (2009). In search of decay in verbal short-term memory [Electronic version]. Journal of experimental psychology: Learning, memory, and cognition, 35(2), pp. 317-333. Retrieved March 4, 2010.
3 Lewandowsky, S., & Oberauer, K. (2008). The word-length effect provides no evidence for decay in short-term memory [Electronic version]. Psychonomic bulletin and review, 15(5), pp. 875-888. Retrieved March 4, 2010.
4 Portrat, S., Barrouillet, P., & Camos, V. (2008). Time-related decay or interference-based forgetting in working memory [Electronic version]. Journal of experimental psychology: learning, memory, cognition, 34(6), pp. 1561-1564. Retrieved March 6, 2010.
5 Oberauer, K., & Lewandowsky, S. (2008). Forgetting in immediate serial recall: decay, temporal distinctiveness, or interference? [Electronic version]. Psychology review, 115(3), pp. 544-576. Retrieved March 6, 2010.
6 Buhusi, C.V., & Meck, W.H. (2006). Interval time with gaps and distractors: Evaluation of the switch, and time-sharing hypothesis [Electronic version]. Journal of experimental psychology: Animal behavior processes, 32(3), pp. 329-338. Retrieved March 6, 2010.
7 ^ Paul Wetham, Andrew Day, Libby Wetham (2006) Psychology for the use with the IB Diploma.
1. Author Unknown. (2007-2008). Ways to Improve Memory. ''Ways to Improve Memory.net''. Retrieved from http://waystoimprovememory.net/
2. Roberts, William A. (June 1972). Short-term memory in the pigeon: Effects of repetition and spacing. ''Journal of Experimental Psychology''. Vol. 94(1). pp. 74-83
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