1.1.4 Memory
Memory: Influences Upon and Optimal Conditions for Encoding, Storage and Retrieval
Memory is defined as the experience, awareness, and recall of sensations, ideas, and events (Klein, 2015).
Memories are processed via encoding, storage and retrieval.
Encoding:
Encoding is the transfer of sound or imager (sensory input) into a form that allows memory registration. The process of learning new information is referred to as “encoding,”. There a numerous aids to assist in encoding memories more easily, such as: mnemonics, primacy-recency effects, and chunking. That is the means by which data is acquired, processed, modified, and finally stored. The following four approaches are commonly used to encode information:
(1) “Visual encoding”, which refers to how something appears
(2) “Acoustic encoding”, which refers to how something sounds;
(3) “Semantic encoding”, which refers to what something means
(4) “Tactile encoding” refers to how something feels.
Even though information can usually get into the memory system through one of these manners, the way it is stored might be different from how it was encoded in the first place (McLeod, 2007).
Storage:
The word “storage” is used to describe “how”, “where”, “how much”, and “for how long” encoded data is kept in the memory system. The modal model of memory (storage) focuses on the fact that there are two types of memory (Tonegawa et al., 2015):
- Long-term memory (LTM)
- LTM capacity is unlimited from minutes to a lifetime.
- Short-term memory (STM)
- STM capacity has been shown to be 7 +/- 2 in digit span experiments.
The encoded information is first stored in the “short-term memory”, and if needed, it is then stored in the “long-term memory”.
Retrieval:
Retrieval is the procedure that enables someone to access the information that has been ‘saved’. The information that is stored in STM and LTM is recalled in distinct ways due to their differences (Tonegawa et al., 2015).
LTM is retrieved by making connections, while STM is retrieved in the order in which information was stored like when you remember where you parked your car by going back to the shopping mall entrance.
LTM memory can be retrieved in two different forms: voluntary (automatic recall) and involuntary (active process).
Primary Working Memory Storage Capacity and the Principle of Chunking
Working memory:
Working memory refers to the ability of the brain to keep information in mind for brief periods, such as when we are making a decision or solving a problem.
Short-term memory understanding was further improved by Baddeley and Hitch (1974). This later became known as Baddeley’s multi-storehouse model, as summarized with subcomponents of working memory:
| A subcomponent of working memory: | Summary: |
| Central Executive | Responsible for higher cognitive processes – planning and problem-solving. |
| Phonological loop | Attempts to explain acoustic coding that happens in STM. |
| Visuospatial sketchpad | Uses visual and spatial information to represent the size, shape and colour of an image. |
| Episodic buffer | Acts as a backup store, communicating with the working memory and LTM. |
Working memory can be tested using the digit span test. Specifically, damage to the left hemisphere and dorsolateral prefrontal cortex will cause deficits in working memory.
Primary working memory capacity: In terms of working memory, primary memory is frequently regarded as a type of limited-capacity storage capable of holding between 3 and 5 items at any given time (Shipstead et al., 2014).
Principle Of chunking:
Each piece of information should be provided in manageable chunks (Sargent et al., 2010). The term “chunking” refers to the process of grouping smaller information units into bigger ones. By combining each data point into a broader whole, it is possible to remember more information. This technique improves memory performance. It allows a person to convey information in a manner that is simple to comprehend and recall for your audience. The idea behind chunking is that our working memory is easily overrun by too much information.
According to research, given an assortment of irrelevant facts to remember, there is a crucial difference in performance at approximately seven items. People can process up to seven pieces of information with ease, but any more than that is tough. Chunking can be a useful memory enhancement technique. By introducing chunking tactics into your daily study routine, you may discover that you are able to retain more information(Fonollosa et al., 2015).
Example: Phone numbers are one the most common examples of chunking. For instance, the sequence 4-7-1-1-3-2-4 would be chunked as 471-1324.
Semantic Episodic and Skills Memories and other Aspects of Long-Term/Secondary Memory
Secondary memory is also referred to as long-term memory. This is a memory you will keep for the rest of your life. These can contain information that is processed, stored, forgotten for a time, and then retrieved.
Semantic memory:
Semantic memory centres on factual and theoretical knowledge of the world and its verbal manifestation(Yee et al., 2014). Therefore, it facilitates language-based interaction. This involves both conceptual and verbal knowledge.
Example: When you eat an apple, you realize that it is a fruit and, based on what you know, you can explain its importance.
Episodic memory:
Episodic memory is centred on the experiences that a person has had during the many stages of his life, and it is primarily responsible for recalling life events(Sugar and Moser, 2019). These are the recollections that have been stored away within the limbic system.
This will depend on a person’s memory from their own point of view, but it won’t take into account numbers and facts that are obvious.
Example: The good time you had at your friend’s wedding with your crew.
Flashbulb memory:
Flashbulb memories are precise recollections of how people first learned about a significant event.
Example: What were you doing when you first learned about the 9/11 twin towers tragedy?
They are more likely to be episodic (of occurrences) than semantic (of facts) recollections. All flashbulb memories have one thing in common: a high level of emotional arousal at the time the experience was committed to memory.
Procedural memory:
Procedural memory is referred to as skill memory. Skill memory focuses mostly on how to perform a complicated task.
Example: Driving a car or a scooter necessitates the execution of a number of sequential tasks.
Long-term or secondary memory:
There are a number of theories that study long-term memory; however, most are based on the storage of information in three different forms: sensory memory, primary memory, and secondary memory. The multi-store model by Atkinson and Shiffrin describes sensory memory, STM and LTM as permanent structural components and explained how information moved between storage systems.
Primary and secondary memories are those that allow us to retain information over longer periods of time(Hartshorne et al., 2019).
Another theory was that LTM is either declarative or non-declarative:
Sensory memory:
Sensory memory is the ability to store information in the immediate environment without being consciously aware of it.
| Sensory memory type: | Summary: |
| Echoic memory | Via auditory stimuli |
| Haptic memory | Via touch stimuli |
| Iconic memory | Via sight stimuli |
Distortion, Schema, Inference, and Elaboration in Relation to Memory
Distortion:
Memory distortions occur when the brain develops fabricated memories. These erroneous memories are subsequently stored in the brain without their validity being evaluated(Schacter et al., 2011).
Example: Occasionally, we may believe that we had a conversation that we never had. Or our memory of a certain day and conversation may differ from that of another individual. When we have memory distortions, we perceive similar circumstances.
Schemas:
The memory of every individual has a collection of schemas. A memory schema is a compilation of past experiences(Ghosh and Gilboa, 2014). Memory is used to recall and activate these events and associations in order to shape judgments and thinking.
Example: The memory of rapid eye movement during sleep.
Inference:
Inference can be viewed as a logical process in which preexisting memories are recovered and merged to answer a fresh query(Joshi et al., 2020). Inferences are missing parts of information that a person fills in based on their existing knowledge, theories, or beliefs.
Example: For instance, if a person enters a room and notices that the digital clocks are flashing, they can “infer” that there was a recent power outage.
Elaboration:
Elaboration is a cognitive learning approach that incorporates any improvement of information that explains or defines the relationship between the material to be learned and information related(Bartsch et al., 2018).
Example: A learner’s previous experience and knowledge or consecutively delivered information.
Schema:
A “schema” is a concept or image of something that happened in the past. Information that is primary or fundamental is referred to as elaboration. Inference – conclusions are drawn from the information. Distortion – the result of poor representation of facts determines how we think, feel and work.
The Process of Forgetting
The inability to access or recall previously taught information is known as forgetting.
The Ebbinghaus curve or the ‘forgetting curve’ postulates that memory retention decreases over time. This curve depicts how information decays over time when no effort is made to keep it. A related notion is memory strength, which relates to the longevity of memory traces in the brain. The longer a person can recall anything, the stronger his or her memory. An Ebbinhaus curve claims that individuals halve their memory of freshly gained knowledge in a couple of days or weeks unless they intentionally examine the subject:
Memory Failure:
| Reason for memory failure: | Summary: |
| Transience | Memory’s decreased accessibility with time. |
| Absent-mindedness | Gaps in concentration and forgetfulness. To some extent, memory is generated, however there is a problem in accessing memory (for example, remembering you left £20 in your pocket but only after it was sent to the dry cleaners). |
| Blocking | The temporary inaccessibility of stored data, as in tip-of-the-tongue syndrome. |
| Suggestion | The assimilation of incorrect information into memory as a result of leading inquiries, dishonesty, and other factors. |
| Bias | Bias refers to retrospective distortions caused by present knowledge and assumptions. |
| Persistence | Unfavourable memories that people can’t get rid of, such as the unrelenting, intrusive memories of post-traumatic stress disorder. |
| Misattribution | The mistaken attribution of memories or the belief that you have seen or heard something you actually have not. Examples include Deja Vu and cryptomnesia. |
Emotional Factors and Retrieval
In Short-Term Memory:
Decay: This takes place when information is not “rehearsed,” which means that it is not given any thought. It is believed that the physical trace of such memories fades over time.
Displacement: When previously stored memories are replaced by more recent ones, a phenomenon known as displacement takes place. Despite the fact that everyone is aware of the immense potential of memory, particularly long-term memory, research conducted by Norman has demonstrated that by using the serial probe approach, numbers can take the place of ones that have been previously memorized (Davis and Zhong, 2017).
Interference: If a person has been trying to memorize similar content, including words that sound very similar to one another, it can be difficult for them to retain the information they have learned.
There are two types of interference: proactive and retroactive. Proactive interference occurs when one’s older memories prevent one from forming new memories (Frise, 2018). Retroactive interference occurs when one’s more recent memories become corrupted by more recent information.
Long-Term Memory:
Long-term is meant to have an infinite amount of capacity and duration. However, information can still be forgotten due to deterioration such as temporary forgetting and interference from other memories.
Emotional factors affecting the process of forgetting:
These include:
- stress
- anxiety
- Feelings of aggression
- Depression
These factors impede attention and prevent the creation of new memories and the recall of existing ones (Roozendaal, 2002).
Retrieval factors affecting the process of forgetting:
These include:
- Positive mood
- Knowledge
- Belief
- Personal experience
The Relevance of this to Memory Disorders and their Assessment
Memory disorders occur when a person has trouble forming and retaining new memories. They can be caused by brain damage, diabetes, other health problems, or psychological disorders(Gold et al., 2019).
Basically, memory disorders are divided into three main groups – amnesia, confabulation, and dementia (Hsieh et al., 2019).
- Amnesia is the loss of memory or the inability to form new memories.
- Confabulation, or false memories, occurs when someone makes up a story about an event that actually has not happened.
- Dementia refers to a decline in mental functioning that results in loss of abilities such as language skills, judgment, emotions and memory.
Memory problems may also be caused by medical conditions, substance abuse, or neurological condition. When a memory impairment has no known origin or is caused by a medical disease, normal brain function will not be present, and the individual’s memories will not be able to be recorded as they should be(Islam et al., 2020).
Amnesia:
Amnesia is associated with damage to the following: medial temporal lobe, hippocampus, and midline diencephalon.
| Type of amnesia: | Summary: |
| Anterograde amnesia | Anterograde amnesia is the inability to form new memories (the inability to transfer new information from the short-term to the long-term store). Although the specific mechanism is unknown, it is considered to be caused primarily by hippocampal injury. |
| Retrograde amnesia | The term “retrograde amnesia” refers to the loss of memory for knowledge obtained prior to the commencement of the amnesia. An exam is a traumatic insult e.g. a head injury. Episodic memory is more vulnerable than semantic memory. |
| Transient global amnesia | Transient global amnesia is a condition characterised by transient memory loss. It typically affects people over the age of 50 and resolves on its own within 24 hours. There is no definite aetiology, but it has been proposed that it is a variant of a migraine, a type of epilepsy, and a TIA presentation (transient ischemic attack). |
| Semantic amnesia | Semantic amnesia impairs semantic memory and manifests mostly as difficulties with language usage and acquisition. |
| Psychogenic amnesia | Psychogenic amnesia (also known as dissociative amnesia) is a memory condition characterised by rapid retrograde episodic memory loss that can last from hours to years. Fugue experiences are a prevalent feature of global psychogenic amnesia, which is defined by a rapid loss of autobiographical memories for the entirety of a person’s past. Situation-specific amnesia (also known as lacunar amnesia) is a memory gap for a traumatic occurrence that can occur in a variety of settings, such as post-traumatic stress disorder (PTSD) or being the victim of an offence. |
| Source amnesia | The inability to remember where, when, or how previously learned information was gained, despite retaining factual knowledge, is referred to as source amnesia. |
Memory assessment:
There are many tests that assess different aspects of memory. The most common and widely used tests to assess a person’s ability to remember information from long-term memory are:
| Test: | Summary: |
| California Verbal Learning Test | Assesses episodic verbal learning and memory and is sensitive to a variety of clinical disorders. The test attempts to link memory deficits with poor performance on certain tasks. It measures encoding, recall and recognition in a single-item presentation mode (auditory-verbal). |
| Rey Auditory Verbal Learning Test | There are five presentations of a 15-word list (list A), each followed by an effort at recall. This is followed by a second 15-word interference list (list B). There is additional testing for delayed recall and recognition. The ability to measure the pace of learning, rather than recall a single stimulus or set stimuli, is a significant characteristic of the AVLT. |
Other tests to examine different aspects of memory include:
- Encoding performance test (EFT)
- “Delayed word recall test” (DWRT)
- WAIS-III and WMS-III.
- Verbal fluency test
References:
(1) Bartsch, L. M., Singmann, H., Oberauer, K. J. M. & Cognition 2018. The Effects of Refreshing and Elaboration on Working Memory Performance, and Their Contributions to Long-term Memory Formation. 46, 796-808.
(2) Davis, R. L. & Zhong, Y. J. N. 2017. The Biology of Forgetting—a Perspective. 95, 490-503.
(3) Fonollosa, J., Neftci, E. & Rabinovich, M. J. P. C. B. 2015. Learning of Chunking Sequences in Cognition and Behavior. 11, E1004592.
(4) Frise, M. 2018. Forgetting. New Directions in the Philosophy of Memory. Routledge.
(5) Ghosh, V. E. & Gilboa, a. J. N. 2014. What is a Memory Schema? A Historical Perspective on Current Neuroscience Literature. 53, 104-114.
(6) Gold, J. M., Barch, D. M., Feuerstahler, L. M., Carter, C. S., Macdonald Iii, a. W., Ragland, J. D., Silverstein, S. M., Strauss, M. E. & Luck, S. J. J. S. B. 2019. Working Memory Impairment Across Psychotic Disorders. 45, 804-812.
(7) Hartshorne, J. K., Makovski, T. J. M. & Cognition 2019. The Effect of Working Memory Maintenance on Long-term Memory. 47, 749-763.
(8) Hsieh, S.-w., Chen, C.-h., Huang, P., Li, C.-h., Yang, S.-t. & Yang, Y.-h. J. N. 2019. The Long-term Risk of Dementia After Transient Global Amnesia: a Population-based Cohort Study in Taiwan. 53, 201-208.
(9) Islam, M. A., Jia, S. & Bruce, N. D. J. A. P. A. 2020. How Much Position Information Do Convolutional Neural Networks Encode?
(10) Joshi, V., Le Gallo, M., Haefeli, S., Boybat, I., Nandakumar, S. R., Piveteau, C., Dazzi, M., Rajendran, B., Sebastian, a. & Eleftheriou, E. J. N. C. 2020. Accurate Deep Neural Network Inference Using Computational Phase-change Memory. 11, 1-13.
(11) Klein, S. B. J. W. I. R. C. S. 2015. What Memory is? 6, 1-38.
(12) Mcleod, S. A. J. R. 2007. Stages of Memory-encoding Storage and Retrieval. 21, 2015.
(13) Roozendaal, B. J. N. O. L. & Memory 2002. Stress and Memory: Opposing Effects of Glucocorticoids on Memory Consolidation and Memory Retrieval. 78, 578-595.
(14) Sargent, J., Dopkins, S., Philbeck, J., Chichka, D. J. J. O. E. P. L., Memory, & Cognition 2010. Chunking in Spatial Memory. 36, 576.
(15) Schacter, D. L., Guerin, S. A. & Jacques, P. L. S. J. T. I. C. S. 2011. Memory Distortion: an Adaptive Perspective. 15, 467-474.
(16) Shipstead, Z., Lindsey, D. R., Marshall, R. L., Engle, R. W. J. J. O. M. & Language 2014. The Mechanisms of Working Memory Capacity: Primary Memory, Secondary Memory, and Attention Control. 72, 116-141.
(17) Sugar, J. & Moser, M. B. J. H. 2019. Episodic Memory: Neuronal Codes for What, Where, and When. 29, 1190-1205.
(18) Tonegawa, S., Pignatelli, M., Roy, D. S. & Ryan, T. J. J. C. O. I. N. 2015. Memory Engram Storage and Retrieval. 35, 101-109.
(19) Yee, E., Chrysikou, E. G. & Thompson-schill, S. L. 2014. Semantic Memory.