Decay theory
Encyclopedia
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. When we learn
something new, a neurochemical
“memory trace” is created. However, over time this trace slowly disintegrates. Actively rehearsing
information is believed to be a major factor counteracting this temporal decline. 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.
in his book “The Psychology of Learning” in 1914. 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 19th century. The decay theory proposed by Thorndike was heavily criticized by McGeoch and his interference theory. 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 Brown-Peterson Paradigm. The theory was again challenged, this time a paper by Keppel and Underwood who attributed the findings to proactive interference. Studies in the 1970s by Reitman tried reviving the decay theory by accounting for certain confounds criticized by Keppel and Underwood. Roediger quickly found problems with these studies and their methods. 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. In addition, McKone 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. One of the biggest criticisms of decay theory is that it cannot be explained as a mechanism and that is the direction that the research is headed.
). Often, evidence tends to favour interference related decay over temporal decay, yet this varies depending on the specific memory system taken into account.
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. 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. No evidence for temporal decay in verbal short-term memory has been found in recent studies of serial recall tasks. Regarding the word-length effect in short-term memory, which states that lists of longer word are harder to recall than lists of short words, researchers argue that interference plays a larger role due to articulation duration being confounded with other word characteristics.
. One situation in which this shows considerable debate is within the complex-span task
of working memory, whereas a complex task is alternated with the encoding of to-be-remembered items. It is either argued that the amount of time taken to perform this task or the amount of interference this task involves cause decay. A 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 information. 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 memory. As processing and maintenance are both crucial components of working memory, both of these processes need to be taken into account when determining which theory of forgetting is most valid. Research also suggests that information or an event’s salience
, or importance, may play a key role. Working memory may decay in proportion to information or an event’s salience. This means that if something is more meaningful to an individual, that individual may be less likely to forget it quickly.
and retrieval failure theory.
while also assuming that retrieval cues play an important role in short term memory. By broadening the view of this theory, it will become possible to account for the inconsistencies and problems that have been found with decay to date.
A model proposed to support decay with neurological evidence places importance on the firing patterns of neurons over time. The neuronal firing patterns that make up the target representation fall out of synchrony over time unless they are reset. The process of resetting the firing patterns can be looked at as rehearsal, and in absence of rehearsal, forgetting occurs. This proposed model needs to be tested further to gain support, and bring firm neurological evidence to the decay theory.
In remembering new information, the brain goes through three stages: registration, retention
, and retrieval. It is only in the retention process that one is able to influence the retention rate if the information is properly organized in your brain. This can be done using these techniques:
Memory
In psychology, memory is an organism's ability to store, retain, and recall information and experiences. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing memory....
fades due to the mere passage of time. Information
Information
Information in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...
is therefore less available for later retrieval as time passes and memory, as well as memory strength, wears away. When we learn
LEARN
LEARN may refer to:* Law Enforcement Agency Resource Network, a website run by the Anti-Defamation League* LEARN diet, a brand name diet product...
something new, a neurochemical
Neurochemical
A neurochemical is an organic molecule, such as serotonin, dopamine, or nerve growth factor, that participates in neural activity. The science of neurochemistry studies the functions of neurochemicals.-Prominent neurochemicals:...
“memory trace” is created. However, over time this trace slowly disintegrates. Actively rehearsing
Memory rehearsal
Memory rehearsal is a term for the role of repetition in the retention of memories, e.g., working memory rehearsal tasks.In the Baddeley's model of working memory, this ability comprises a central executive and two buffers - the phonological loop and the visuo—spatial sketch pad. Both storage...
information is believed to be a major factor counteracting this temporal decline. 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
Short-term memory
Short-term memory is the capacity for holding a small amount of information in mind in an active, readily available state for a short period of time. The duration of short-term memory is believed to be in the order of seconds. A commonly cited capacity is 7 ± 2 elements...
system, meaning that older memories (in long-term memory
Long-term memory
Long-term memory is memory in which associations among items are stored, as part of the theory of a dual-store memory model. According to the theory, long term memory differs structurally and functionally from working memory or short-term memory, which ostensibly stores items for only around 20–30...
) are often more resistant to shocks or physical attacks on the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
. It is also thought that the passage of time alone cannot cause forgetting
Forgetting
Forgetting refers to apparent loss of information already encoded and stored in an individual's long term memory. It is a spontaneous or gradual process in which old memories are unable to be recalled from memory storage. It is subject to delicately balanced optimization that ensures that...
, and that Decay Theory must also take into account some processes that occur as more time passes.
History
The term decay theory was first coined by Edward ThorndikeEdward Thorndike
Edward Lee "Ted" Thorndike was an American psychologist who spent nearly his entire career at Teachers College, Columbia University. His work on animal behavior and the learning process led to the theory of connectionism and helped lay the scientific foundation for modern educational psychology...
in his book “The Psychology of Learning” in 1914. 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
Hermann Ebbinghaus
Hermann Ebbinghaus was a German psychologist who pioneered the experimental study of memory, and is known for his discovery of the forgetting curve and the spacing effect. He was also the first person to describe the learning curve...
in the late 19th century. The decay theory proposed by Thorndike was heavily criticized by McGeoch and his interference theory. 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 Brown-Peterson Paradigm. The theory was again challenged, this time a paper by Keppel and Underwood who attributed the findings to proactive interference. Studies in the 1970s by Reitman tried reviving the decay theory by accounting for certain confounds criticized by Keppel and Underwood. Roediger quickly found problems with these studies and their methods. 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. In addition, McKone 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. One of the biggest criticisms of decay theory is that it cannot be explained as a mechanism and that is the direction that the research is headed.
Inconsistencies
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 theoryInterference theory
-History:Bergström, a German psychologist, is credited as conducting the first study regarding interference in 1892. His experiment was similar to the Stroop task and required subjects to sort two decks of card with words into two piles. When the location was changed for the second pile, sorting...
). Often, evidence tends to favour interference related decay over temporal decay, yet this varies depending on the specific memory system taken into account.
Short-Term Memory
Within the short-term memoryShort-term memory
Short-term memory is the capacity for holding a small amount of information in mind in an active, readily available state for a short period of time. The duration of short-term memory is believed to be in the order of seconds. A commonly cited capacity is 7 ± 2 elements...
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. 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. No evidence for temporal decay in verbal short-term memory has been found in recent studies of serial recall tasks. Regarding the word-length effect in short-term memory, which states that lists of longer word are harder to recall than lists of short words, researchers argue that interference plays a larger role due to articulation duration being confounded with other word characteristics.
Working Memory
Both theories are equally argued in working memoryWorking memory
Working memory has been defined as the system which actively holds information in the mind to do verbal and nonverbal tasks such as reasoning and comprehension, and to make it available for further information processing...
. One situation in which this shows considerable debate is within the complex-span task
Memory span
In psychology and neuroscience, memory span is the longest list of items that a person can repeat back in correct order immediately after presentation on 50% of all trials. Items may include words, numbers, or letters. The task is known as digit span when numbers are used. Memory span is a common...
of working memory, whereas a complex task is alternated with the encoding of to-be-remembered items. It is either argued that the amount of time taken to perform this task or the amount of interference this task involves cause decay. A 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 information. This theory gives more credit to the active rehearsal of information, as refreshing items to be remembered focuses attention
Attention
Attention is the cognitive process of paying attention to one aspect of the environment while ignoring others. Attention is one of the most intensely studied topics within psychology and cognitive neuroscience....
back on the information to be remembered in order for it to be better processed and stored in memory. As processing and maintenance are both crucial components of working memory, both of these processes need to be taken into account when determining which theory of forgetting is most valid. Research also suggests that information or an event’s salience
Salience (neuroscience)
The salience of an item – be it an object, a person, a pixel, etc – is the state or quality by which it stands out relative to its neighbours...
, or importance, may play a key role. Working memory may decay in proportion to information or an event’s salience. 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 explanations. 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 motivated forgettingRepressed memory
Repressed memory is a hypothetical concept used to describe a significant memory, usually of a traumatic nature, that has become unavailable for recall; also called motivated forgetting in which a subject blocks out painful or traumatic times in one's life...
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. 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.Hybrid Theories
The future of decay theory, according to Nairne (2002), should be the development of hybrid theories that incorporate elements of the standard modelBaddeley's Model of Working Memory
Alan Baddeley and Graham Hitch proposed a model of working memory in 1974, in an attempt to describe a more accurate model of short-term memory....
while also assuming that retrieval cues play an important role in short term memory. By broadening the view of this theory, it will become possible to account for the inconsistencies and problems that have been found with decay to date.
Neuronal Evidence
Another direction of future research is to tie decay theory to sound neurological evidence. As most current evidence for decay leaves room for alternate explanations, studies indicating a neural basis for the idea of decay will give the theory new solid support. Jonides et al. (2007) found neural evidence for decay in tests demonstrating a general decline in activation in posterior regions over a delay period. Though this decline was not found to be strongly related to performance, this evidence is a starting point in making these connections between decay and neural imaging.A model proposed to support decay with neurological evidence places importance on the firing patterns of neurons over time. The neuronal firing patterns that make up the target representation fall out of synchrony over time unless they are reset. The process of resetting the firing patterns can be looked at as rehearsal, and in absence of rehearsal, forgetting occurs. This proposed model needs to be tested further to gain support, and bring firm neurological evidence to the decay theory.
Ways to Improve Memory
There are several methods that can be employed to improve one’s memory skills. Recall that the decay theory states that as time passes with a memory trace not being used, it becomes increasingly difficult for that pattern of neural activity to become reactivated, or in other words to retrieve that memory. The key is that information must be retrieved and rehearsed or it will eventually be lost.In remembering new information, the brain goes through three stages: registration, retention
Retention
Retention may refer to:* Retention, in learning, the ability to retain facts and figures in memory ** Selective retention* Cultural retention* Customer retention...
, and retrieval. It is only in the retention process that one is able to influence the retention rate if the information is properly organized in your brain. This can be done using these techniques:
- Recall using cues. Connecting a piece of unfamiliar information with, say, a visual cue can help in remembering that piece of information much more easily.
- Use the Rule of 7. Your brain can only story approximately seven items simultaneously in short-term memory. Lists and categories should therefore contain no more than seven items.
- Teach it. This is another way to speed up the process of learning new information.
- Use mnemonic devices and acronyms. This is a preferable method to memorize lists and increase chances of long-term memory storage.