Selective amnesia

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Selective amnesia is a type of amnesia in which the sufferer loses only certain parts of their memory. Common elements that may be forgotten are relationships, where they live, and certain special abilities and talents (e.g., juggling, whistling, instrumental talents, etc.).

Contents

Factors

Emotional connotations

People may be more susceptible to hypnotic amnesia if the words they are asked to forget (or remember) have significant emotional connotations. [1] Clemes (1964) was able to identify participants’ critical words—words that are linked with inner conflict—and neutral words—words that are not linked with inner conflict. He then placed the participants under hypnosis and listed nine critical words and nine neutral words. Participants were then instructed, under the influence of hypnosis, to forget half of the words they were given. They found that participants are more likely to forget critical words than neutral words. [1] However, a replication study conducted by Stam and colleagues (1980) failed to replicate these results, suggesting that these conclusions may be invalid. [2]

Familiarity

One's familiarity with a task influences how selective amnesia affects the subject's memories. [3] To study this phenomenon, Lewis and colleagues (1969) taught rats a simple passive avoidance task, a fear-aggravated test used to evaluate learning and memory in rodent models. Some rats were allowed to familiarize themselves with the task while others were only allowed to experience the task once. After the rats had completed their task a pre-determined number of times, the experimenters administered an electroconvulsive shock to the rats meant to induce selective amnesia. These shocks varied in duration, lasting from zero to five seconds. The results of this study showed that only the rats unfamiliar with the task demonstrated selective amnesia 24 hours later. The rats that were familiar with the task seemed to display normal memory for the task. Thus, there might be a particular stage in the memory process that is vulnerable to selective amnesia. The current hypothesis is that this vulnerable stage is located during the transition from active memory to short term memory. [3]

Types of memory

In an experiment investigating the functional role of the entorhinal cortex entorhinal cortex pars medialis in memory formation, Hölscher and Schmidt (1994) found that they could produce selective amnesia for specific types of memories by creating lesions that is painful in the brains of rats. [4] In this experiment, both lesioned and non-lesioned rats were placed in an eight-armed maze with food in one of the arms. The rats had to orientate themselves to their surroundings to find the food. Rats with lesions showed significant memory problems, including memory failure and increased memory retrieval times, during trials in which they had to orient themselves using distal cues, the most distant cues. The researcher labeled these memory problems as selective amnesia. They also found that lesion-ed rats had a more difficult time finding the food when it was moved to a different arm. When the lesion-ed rats had to orient themselves in an egocentric egocentric test using proprioceptive proprioceptive cue, there were no detectable memory defects. This finding suggests that the type of memory a subject is trying to remember may influence the subject's susceptibility to selective amnesia. [4]

Serial position

Watanabe and Yanagisawa (2000) found that the serial position effect may determine the task's susceptibility to selective amnesia. [5] In their study, the researchers put mice through a maze with six ‘gates’. Each of these ‘gates’ had three doors, two of them locked and the third unlocked. They found that the mice were better at remembering the position of the unlocked gate if the gate's position was taught at the beginning or end of the trial. These findings provide support for the primacy effect and recency effect of serial positioning. Watanabe and Yanagisawa then took this a step further and injected some of the mice with high and low doses of scopolamine. At low doses, scopolamine intensified the primacy effect of serial positioning, and at high doses, scopolamine created major defects in general learning abilities. Their findings suggest that scopolamine may contain a property which plays a role in selective amnesia, specifically as it relates to serial positioning. [5]

Memory consolidation

Some research suggests that selective amnesia may be the result of a deficit in memory consolidation. [6] Mathis and colleagues (1992) investigated the effect of protein kinase C (PKC) on the memories of rats and found that they could induce a dose-dependent deficit in memory retention. They classified this memory deficit as selective amnesia. In this experiment, mice were trained to avoid a certain leg of a Y-shaped maze. After training, the experimenters gave a dose of NPC 15437 to the mice and noticed that the mice exhibited selective amnesia for the temporal aspect of the task but not the spatial aspect. The experimenters eliminated the possibly that this amnesia was due to a deficit in memory acquisition and retrieval, concluding that PKC interferes with the mechanisms behind memory consolidation. [6]

Use in treatment

It has been suggested that inducing selective amnesia for particular events or stimuli in patients may be an effective tool in psychotherapy. [7] Alexander (1953) found that administering electroconvulsive therapy (ECT) to patients suffering from a traumatic life event induces selective amnesia for the traumatic event without affecting the patient's surrounding memories. This finding, as well as other similar findings, has been used to form a hypothesis concerning the mechanisms underlying ECT. This hypothesis states that the most decisive effect of ECT is the arousal of the active defensive operations in the brain. They further hypothesize that the arousal of these operations makes ECT an effective treatment for depression and other psychotic disorders in which the brain's defensive operations are ineffective. This hypothesis would also explain why ECT is an ineffective treatment for disorders in which the defensive operations are overactive such as anxiety disorders. Thus, selective amnesia, if utilized under the correct circumstances, may be useful in a therapeutic setting. [7]

Hypnosis

Overview

Hypnotic amnesia, or forgetting under hypnosis, appears to be similar to naturally occurring clinical amnesia. However, hypnotic amnesia is distinct from naturally occurring amnesia because forgotten memories can be restored through a hypnotist's prearranged signal. Also, hypnotic amnesia is usually incomplete, meaning that the participants do not forget everything they were instructed to forget. Due to this trait, hypnosis can be used to research selective amnesia through studies that direct attention to the targets, or erased memories, of hypnotic amnesia. [8]

Use in memory research

Researchers have used the relationship between hypnosis and selective amnesia to study specific memory processes including memory recall and retrieval cues. [9] [10] Bertrand and Spanos (1984) were able to study the process of memory recall by hypnotizing a group of undergraduate students, teaching the students three lists of words, and compelling the students to forget certain parts of these lists. They discovered that clustering related information together during initial learning may play a significant role in memory recall. [9] In another experiment, Davidson and Bower (1991) found that participants with selective amnesia due to hypnosis were able to remember all non-amnesic information with near perfect recall. They also noticed that the participants recalled this information in very structured ways (usually in the same order the information was given). These results suggest that people experiencing hypnosis are still able to attend to important retrieval cues even though they are not able to recall the material specifically targeted by the amnesia. [10]

In everyday life

All people experience selective amnesia in their lives, and this selective amnesia may allow individuals to use their attention more effectively. [11] In these studies, selective amnesia is defined as the phenomena experienced when a participant pays attention to the information given but then almost immediately forgets it. Rodrigues (2011) conducted a study in which participants were put into pairs and each pair was given five minutes to interact with an assigned stimuli. The participants’ actions and speech were recorded during this time. After the five minutes were completed, the experimenter questioned the participants about why the participants made certain decisions or said certain things. Rodrigues found that inattention blindness, attention capture, and selective amnesia all played a role in the participant's overall accuracy. Thus, even though most other forms of amnesia are harmful, selective amnesia may play a practical, and even helpful, role in our lives. [11]

Case studies

Because of the relative rarity of naturally occurring clinical selective amnesia, many case studies have been undertaken to learn more about the cause and course of the disorder.

Patient A

The following section is a summary of a case study performed by Scheerer and Goldstei in 1966. [12] Patient A was a 36-year-old mechanic, formerly in the Navy, who had a wife and three children. Due to an unfortunate accident, Patient A's frontal lobe experienced significant damage. This brain damage resulted in a slight decrease in cognitive and physical skills as well as a change in personality. There were also some specific memory problems suggestive of selective amnesia. For example, Patient A worked with the same doctor for many years. However, if the doctor was absent for several days, Patient A was unable to remember him or, if Patient A did remember him, he thought the doctor was a Naval officer. Also, Patient A could only vaguely remember events that happened recently. For instance, he could remember if someone had visited him the day before but could not remember who had visited him. He could also report that he had formerly been in the Navy and that he had a wife and children, but there were many gaps and inconsistencies in his memory. While studying these inconsistencies, Scheerer and Goldstei found that Patient A's memory was sharpest for positive memories and weakest for negative memories. The study of Patient A gives evidence to the theory that patients with selective amnesia cling to specific memories, specifically positive memories. However, this fixation on positive memories causes patients to misremember negative or neutral life events, causing their memory to appear disjointed and defective. [12]

Patient B

The following section is a summary of a case study performed by Sirigu and Grafman in 1996. [13] Patient B was a male in his fifties. He suffered from a heart attack that caused damage to his brain secondary to cerebral anoxia. Due to his injury, he developed severe selective amnesia for the people and dates associated with both personal and public events. Though he could describe what happened during the event as well as the setting of the event, he could not give any information about the event's date or the people involved. His amnesia was temporally limited, affecting only his memories of the last two to three decades. This finding suggests that specific aspects of knowledge is stored separately, allowing for selective amnesia to affect one aspect of an event and not another. [13]

Related Research Articles

Recall in memory refers to the mental process of retrieval of information from the past. Along with encoding and storage, it is one of the three core processes of memory. There are three main types of recall: free recall, cued recall and serial recall. Psychologists test these forms of recall as a way to study the memory processes of humans and animals. Two main theories of the process of recall are the two-stage theory and the theory of encoding specificity.

Source amnesia is the inability to remember where, when or how previously learned information has been acquired, while retaining the factual knowledge. This branch of amnesia is associated with the malfunctioning of one's explicit memory. It is likely that the disconnect between having the knowledge and remembering the context in which the knowledge was acquired is due to a dissociation between semantic and episodic memory – an individual retains the semantic knowledge, but lacks the episodic knowledge to indicate the context in which the knowledge was gained.

Spatial memory Memory about ones environment and spatial orientation

In cognitive psychology and neuroscience, spatial memory is a form of memory responsible for the recording and recovery of information needed to plan a course to a location and to recall the location of an object or the occurrence of an event. Spatial memory is necessary for orientation in space. Spatial memory can also be divided into egocentric and allocentric spatial memory. A person's spatial memory is required to navigate around a familiar city. A rat's spatial memory is needed to learn the location of food at the end of a maze. In both humans and animals, spatial memories are summarized as a cognitive map.

In neurology, retrograde amnesia (RA) is a loss of memory-access to events that occurred or information that was learned in the past. It is caused by an injury or the onset of a disease. It tends to negatively affect episodic, autobiographical, and declarative memory, while keeping procedural memory intact without increasing difficulty for learning new information. RA can be temporally graded, or more permanent based on the severity of its cause. It is usually consistent with Ribot's law. The law states that subjects are more likely to lose memories closer to the traumatic incident than more memories that happened further from the incident. The type of information that is forgotten can range from a specific memory, such as a single event, or a more general memory. This would resemble generic amnesia. Anterograde amnesia is a similar condition that deals with the inability to form new memories following the onset of an injury or disease.

Explicit memory is one of the two main types of long-term human memory, the other of which is implicit memory. Explicit memory is the conscious, intentional recollection of factual information, previous experiences, and concepts. This type of memory is dependent upon three processes: acquisition, consolidation, and retrieval. Explicit memory can be divided into two categories: episodic memory, which stores specific personal experiences, and semantic memory, which stores factual information. Explicit memory requires gradual learning, with multiple presentations of a stimulus and response.

State-dependent memory or state-dependent learning is the phenomenon where people remember more information if their physical or mental state is the same at time of encoding and time of recall. State-dependent memory is heavily researched in regards to its employment both in regards to synthetic states of consciousness as well as organic states of consciousness such as mood. While state-dependent memory may seem rather similar to context-dependent memory, context-dependent memory involves an individual's external environment and conditions while state-dependent memory applies to the individual's internal conditions.

In psychology, memory inhibition is the ability not to remember irrelevant information. The scientific concept of memory inhibition should not be confused with everyday uses of the word "inhibition". Scientifically speaking, memory inhibition is a type of cognitive inhibition, which is the stopping or overriding of a mental process, in whole or in part, with or without intention.

Age regression in therapy is a psycho-therapeutic process that aims to facilitate access to childhood memories, thoughts, and feelings. Age regression can be induced by hypnotherapy, which is a process where patients move their focus to memories of an earlier stage of life in order to explore these memories or to access difficult aspects of their personality.

Retrospective memory is the memory of people, words, and events encountered or experienced in the past. It includes all other types of memory including episodic, semantic and procedural. It can be either implicit or explicit. In contrast, prospective memory involves remembering something or remembering to do something after a delay, such as buying groceries on the way home from work. However, it is very closely linked to retrospective memory, since certain aspects of retrospective memory are required for prospective memory.

In psychology, context-dependent memory is the improved recall of specific episodes or information when the context present at encoding and retrieval are the same. In a simpler manner, "when events are represented in memory, contextual information is stored along with memory targets; the context can therefore cue memories containing that contextual information". One particularly common example of context-dependence at work occurs when an individual has lost an item in an unknown location. Typically, people try to systematically "retrace their steps" to determine all of the possible places where the item might be located. Based on the role that context plays in determining recall, it is not at all surprising that individuals often quite easily discover the lost item upon returning to the correct context. This concept is heavily related to the encoding specificity principle.

Emotion can have a powerful effect on humans and animals. Numerous studies have shown that the most vivid autobiographical memories tend to be of emotional events, which are likely to be recalled more often and with more clarity and detail than neutral events.

In psychology, implicit memory is one of the two main types of long-term human memory. It is acquired and used unconsciously, and can affect thoughts and behaviours. One of its most common forms is procedural memory, which allows people to perform certain tasks without conscious awareness of these previous experiences; for example, remembering how to tie one's shoes or ride a bicycle without consciously thinking about those activities.

<span class="mw-page-title-main">Amnesia</span> Cognitive disorder where the memory is disturbed or lost

Amnesia is a deficit in memory caused by brain damage or disease, but it can also be caused temporarily by the use of various sedatives and hypnotic drugs. The memory can be either wholly or partially lost due to the extent of damage that was caused. There are two main types of amnesia: retrograde amnesia and anterograde amnesia. Retrograde amnesia is the inability to retrieve information that was acquired before a particular date, usually the date of an accident or operation. In some cases the memory loss can extend back decades, while in others the person may lose only a few months of memory. Anterograde amnesia is the inability to transfer new information from the short-term store into the long-term store. People with anterograde amnesia cannot remember things for long periods of time. These two types are not mutually exclusive; both can occur simultaneously.

Motivated forgetting is a theorized psychological behavior in which people may forget unwanted memories, either consciously or unconsciously. It is an example of defence mechanism, since these are unconscious or conscious coping techniques used to reduce anxiety arising from unacceptable or potentially harmful impulses thus it can be a defence mechanism in some ways. Defence mechanisms are not to be confused with conscious coping strategies.

The study of memory incorporates research methodologies from neuropsychology, human development and animal testing using a wide range of species. The complex phenomenon of memory is explored by combining evidence from many areas of research. New technologies, experimental methods and animal experimentation have led to an increased understanding of the workings of memory.

Memory gaps and errors refer to the incorrect recall, or complete loss, of information in the memory system for a specific detail and/or event. Memory errors may include remembering events that never occurred, or remembering them differently from the way they actually happened. These errors or gaps can occur due to a number of different reasons, including the emotional involvement in the situation, expectations and environmental changes. As the retention interval between encoding and retrieval of the memory lengthens, there is an increase in both the amount that is forgotten, and the likelihood of a memory error occurring.

Childhood amnesia, also called infantile amnesia, is the inability of adults to retrieve episodic memories before the age of two to four years, as well as the period before the age of ten of which some older adults retain fewer memories than might otherwise be expected given the passage of time. The development of a cognitive self is also thought by some to have an effect on encoding and storing early memories.

Retrieval-induced forgetting (RIF) is a memory phenomenon where remembering causes forgetting of other information in memory. The phenomenon was first demonstrated in 1994, although the concept of RIF has been previously discussed in the context of retrieval inhibition.

Post-hypnotic amnesia is the inability in hypnotic subjects to recall events that took place while under hypnosis. This can be achieved by giving individuals a suggestion during hypnosis to forget certain material that they have learned either before or during hypnosis. Individuals who are experiencing post-hypnotic amnesia cannot have their memories recovered once put back under hypnosis and is therefore not state dependent. Nevertheless, memories may return when presented with a pre-arranged cue. This makes post-hypnotic amnesia similar to psychogenic amnesia as it disrupts the retrieval process of memory. It has been suggested that inconsistencies in methodologies used to study post-hypnotic amnesia cause varying results.

Spontaneous recovery is a phenomenon of learning and memory that was first named and described by Ivan Pavlov in his studies of classical (Pavlovian) conditioning. In that context, it refers to the re-emergence of a previously extinguished conditioned response after a delay. Such a recovery of "lost" behaviors can be observed within a variety of domains, and the recovery of lost human memories is often of particular interest. For a mathematical model for spontaneous recovery see Further Reading.

References

  1. 1 2 Clemes, S. R. (1964). Repression and hypnotic amnesia. Journal of Abnormal and Social Psychology, 69, 62-69
  2. ↑ Stam, H. J., Radtke-Bodorik, H., & Spanos, N. P. (1980). Repression and hypnotic amnesia: A failure to replicate and an alternative formulation. Journal of Abnormal Psychology, 89(4), 551-559
  3. 1 2 Lewis, D. J., Miller, R. R., & Misanin, J. R. (1969). Selective amnesia in rats produced by electroconvulsive shock. Journal of Comparative and Physiological Psychology, 69(1), 136-140
  4. 1 2 Hölscher, C., & Schmidt, W. J. (1994). Quinolinic acid lesion of the rat entorhinal cortex pars medialis produces selective amnesia in allocentric working memory (WM), but not in egocentric WM. Behavioral Brain Research, 63(2), 187-194
  5. 1 2 Watanabe, S., Yanagisawa, N. (2000). Serial position effect and selective amnesia induced by scopolamine in mice. Nihon Shinkei Seishin Yakurigaku Zasshi = Japanese Journal of Psychopharmacology. 20(1), 17-20
  6. 1 2 Mathis, C., Lehmann, J., Ungerer, A. (1992). The selective protein-kinase-C inhibitor, NPC-15437, induces specific deficits in memory retention in mice. European Journal of Pharmacology. 220(1), 107-110
  7. 1 2 Alexander, L. (1953). The effect of electroshock on a "normal" person under recent stress: An experiment elucidating the influence of electroshock on the defensive operations of the ego. The American Journal of Psychiatry, 109, 696-698
  8. ↑ Hilgard, E. R., & Hommel, L. S. (1961) Selective amnesia for events within hypnosis in relation to repression. Journal of Personality, 29, 205-216
  9. 1 2 Bertrand, L. D., & Spanos, N. P. (1984). The organization of recall during hypnotic suggestions for complete and selective amnesia. Imagination, Cognition and Personality, 4(3), 249-261
  10. 1 2 Davidson, T. M., & Bowers, K. S. (1991). Selective hypnotic amnesia: Is it a successful attempt to forget or an unsuccessful attempt to remember? Journal of Abnormal Psychology, 100(2), 133-143
  11. 1 2 Rodrigues, S. (2011). Using chemistry simulations: attention capture, selective amnesia and inattentional blindness. Chemistry Education Research and Practice. 12(1), 40-46
  12. 1 2 Scheerer, M., Goldstei, G. (1966). Denial and selective amnesia following brain damage – A case study. Neuropsychologia. 4(4), 357-363
  13. 1 2 Sirigu, A., & Grafman, J. (1996). Selective impairments within episodic memories. Cortex: A Journal Devoted to the Study of the Nervous System and Behavior, 32(1), 83-95
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