Are we able to control memory – and forgetting?

Keeping a Spotless Mind: The neuroscience of "motivated forgetting"

https://www.youtube.com/watch?v=NTQd--o61NQ

Prof. Michael Anderson

This is an interesting lecture by Prof. Michael Anderson who presents his case very clearly.

Prof. Anderson works at Cambridge University.  He believes that memory, like other aspects of cognition and behavior, is something we can control and as such it poses for us problems of control.  Anderson studies the mechanisms that allow us to suppress unwanted memories.  He studies the role of frontal systems of inhibitory control in forgetting processes.

Here are some of the interesting things he says in the:

Is forgetting good or bad?

Every one of us experiences frustration when he can't retrieve things that he is sure he knows, or when he can't remember a significant experience from his past about which he hears from someone else.

But there are many advantages to forgetting.  We tend to forget things that arise negative emotions like fear, shame and guilt.  We forget in order to be able to forgive – forgive ourselves for things we've done and are not proud of, and forgive others.  We forget things that threaten our self esteem.  Sometimes we forget our failings (or at least remember them vaguely, not in detail and not with the same emotional intensity).  This gives us strength to face similar situations and try again.

How do we forget?

The forgetting mechanism that Prof. Anderson suggests in this lecture is related to inhibitory control.  We know the term as part of executive functions.  Inhibition is the suppression of a strong and wrong response for a weak and correct one.  The more automatic a task is, the stronger the inhibition we will need to apply in order to stop it.  Prof.  Anderson gives an example of a cactus plant that falls off a table.  Our automatic reaction is to catch it, but there could be uncomfortable consequences…  The preferred and weak response would be to refrain from catching it and to clean the floor later (cautiously).

This is an example of an inhibition of a motor response.  Anderson argues that inhibitory control also helps us to control memory - to control what we retrieve from memory.

  

Sometimes we see or hear a stimulus that automatically invokes a specific memory.  But we don't always allow that memory to reach consciousness.  Sometimes the memory is irrelevant for our purpose at that moment, and sometimes it is emotionally difficult.  We can stop such memories and not experience them.  How?

In order to study this Anderson and his friends used a simple model of learning word pairs.  Participants in the study learned random word pairs like "picture – scissors"; "handle – flower"; "chimney – dog".  Then they were presented with the first word of each pair, and had to respond with the second word. 

In the second phase of the experiment the researchers divided the word pairs into three groups.

The first word of each pair in the first group was presented in green.  The participants responded with the second word– just like in the first phase of the study.  For example, they saw the word "picture" and responded with "scissors".

The first word of each pair in the second group was presented in red.  The participants were instructed that when they see a red word, they should stop their thoughts about that word's pair and not let it reach consciousness.  For example, they saw the word "handle" and were asked not to think about its pair.

The word pairs of the third group were not presented in this stage at all.

The third phase was a repetition of the first phase.  They presented the first word of each pair of all three groups, and asked the participants to say the second word. 

The green word pairs (like "picture – scissors") were recalled best.  These were trained in both phase one and two.  The word pairs that were not presented in the second phase at all (like "chimney – dog") were less well recalled.  The red word pairs that participants were asked to suppress (not to allow the second word to reach consciousness,  like the pair "handle – flower") were the least well recalled.

This means that we can intentionally forget when we try not to let certain information enter consciousness.  Anderson calls this Suppression Induced Forgetting.

Not all the stimuli we encounter, that can provoke a specific memory, would actually provoke that memory or strengthen it.  It depends on our inner stance or attitude towards that memory.  If we don't want to remember, these stimuli may actually help us to suppress that memory. 

Anderson and his friends found out, that when people suppress memories actively (like when they look at a red word and are asked not to think about its pair), there is a significant inhibition in the activity of the hippocampus in both sides of the brain!  The hippocampus is one of the brain structures that are the most important for memory.  The degree to which the hippocampus is suppressed when people look at a "red" word predicts the degree of forgetting of that word's pair in the third phase of the experiment.

Are we able to inhibit only specific unwanted memories, or is the inhibition more global, also affecting wanted memories?

Apparently, inhibition tends to be global.  Anderson argues that when we suppress an unwanted memory, it is accompanied by an "amnestic shadow".  When we encounter a stimulus that raises an unwanted memory, we suppress not only this specific memory, but also other completely neutral events, that are unrelated to that memory, that happened before and after we encountered that arousing stimulus. 

And thus stimuli that arise unwanted memories can interrupt learning of completely different, neutral things.

And so, following trauma there sometimes is a period of memory loss, even for things that are unrelated to the trauma.  In the past people thought it is related to stress, distractedness and sleep loss.  Anderson adds a fourth cause – suppression of the memory of the traumatic event that also affects other memories.

Not all of us can control memories or inhibit unwanted memories.  Children younger than 10-12, old people, people with anxiety and depression, ADHD, PTSD and brain injury have more difficulty doing it. 

Is episodic memory a (narrow) cognitive ability? Part three: Individual differences in episodic memory – the case of especially poor episodic memory

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Can episodic memory be a (narrow) cognitive ability?  It has to fulfill a number of conditions for that.  In the first post of this series we've seen that episodic memory develops through the lifetime.  In the second post we've began to look into individual differences in episodic memory.  We've discussed people with especially high episodic memory.

In this post we'll discuss a group of people with an especially poor episodic memory. 

First, a quick reminder of concepts (you can skip to the green color below):

Episodic memory is memory for life events that we'd experienced in a specific place at a specific time.  The hallmark of episodic memory is the experience of mentally "being there".

 Autobiographical memory is composed of episodic memory and semantic knowledge about ourselves and about things that took place in the world during our lifetimes. Semantic knowledge about the self is, for example, knowledge about our character and hobbies and about places we've been to, in a way that is not necessarily tied with specific episodic memories (I know I'd visited a specific place and know what it looks like, but don't remember the experience itself).

Semantic memory is the fund of knowledge we've accumulated over the years (facts, ideas, word and concept meanings, knowledge about our culture).

In 2004 a woman named Susan McKinnon read a paper about psychologist Endel Tulving, that drew the distinction between semantic and episodic memory.  The paper presented a case of a man whose episodic memory was negatively affected as a result of brain damage following a car accident. McKinnon realized that that man's symptoms resemble her experiences (minus the brain damage).

Tulving expressed his belief that there are intelligent and completely healthy people with no ability to remember personal experiences.  These people have poor episodic memory.  Tulving thought that soon these people will be discovered.  McKinnon realized Tulving is referring to people like her. 

McKinnon is healthy, she is married and has a family.  She is now retired and in the past has worked as a professional.  She doesn't remember any events of her life.  She doesn't remember good and exciting events, arguments or traumatic events.  She knows about the existence of these events but has no experience of them.  She doesn't remember books she'd read or movies or TV series she'd watched.  Her ability to form mental images is not very good.

In 2006 McKinnon decided to approached Dr. Brian Levine who worked with Tulving.  Levine tested her and she became the first person to be diagnosed with SDAM – severely deficient autobiographical memory.  Later Levine found two more people with a similar autobiographical memory, and in 2015 published with his colleagues Palombo, Alain, Söderlund & Khuu a paper about SDAM.  Since the paper's publication, hundreds of people approached Dr Levine thinking they too have SDAM.  Levin's group now tests these people.  Levine assumes he'll find less than 15 people with SDAM in this group.

The three people with SDAM are intelligent people (their IQs are above 110), they are all well educated (one of them has a Phd.) and they all work. Their poor autobiographical memory does not affect their everyday functioning.  These people are healthy, they do not suffer head injuries, neurological diseases or psychological trauma.  Two of them have had a single episode of depression many years ago, when they were adolescents.  Two out of three are in long term relationships and one is single.

All of them realized they have poor autobiographical memory during late adolescence or early adulthood. 

The researchers compared them with 15 people similar in age (47 on average) and education (16.5 years of education on average). 

Of the cognitive tests, the only measure all three were poor at was recall of the RCFT figure.      

The authors think that visual recall is inherent to autobiographical remembering.  That is, when we recall a past event we create a visual image of it.  They cite another study in which two healthy people with a total inability to form visual imagery throughout their lives had poor ability to relive episodic events.  One of them, who by chance had neuropsychological testing in the past, had poor visual memory, and poor RCFT performance. 

How was autobiographical memory assessed in this study?

Each person of the SDAM and the control group chose two events from each of six life periods:  a week ago, a month ago, a year ago, ten years ago, during adolescence and in childhood. Each of these events had to have happened at a specific time and place.  The people could look at almanacs or ask people close to them to name such events (for instance, "on July 2016 you've visited Seorak Park in South Korea").  The consulted people were asked not to add any details about the event.

Each person of the SDAM and the control group elaborated about these events to the best of his ability.  The researchers analyzed the stories and classified the details to be episodic (directly related to the main event, specific to time and space, creates a feeling of re-experience) or semantic/"external" (for example, facts about Korea of about other places in Korea which are not necessarily related to the same visit). 

The researchers found that the people with SDAM produced much less episodic details relative to the control group – but only for events that happened during youth and adolescence. 

The number of episodic details that the three people with SDAM could tell about events in later lifetimes was not significantly different than that of the control group.  This was so despite the fact that SDAM people said they don't have an experience of these events.  How could this be?

The researchers assume that SDAM people could provide episodic-like details as a result of activating non episodic processes (semantic processes).  SDAM people are used to make up for the lack of personal experience by becoming familiar with the story of the event.  The story of the event is retold each time the event is mentioned, and people who were present when the event took place have a chance to add details to the retelling.  Pictures from the event also enrich the story.  I'll also hypothesize that events from the remote past are less often spontaneously mentioned, and are mentioned less in the company of people who took part in them and can enrich the story.

Apparently it's hard to distinguish between episodic details and episodic-like details.  Often "rememberer" himself has difficulty distinguishing between them.  Each time we tell an episodic event we combine episodic details and episodic-like details.  I'm not sure that we can distinguish between small details that we remember directly from an event that occurred many years ago, and small details that someone else who was present in the event added to the event's story.  During remembering we are also assisted, without being aware of it, by a "script" or a "schema" according to which such an event is supposed to happen.

This emphasizes the extent to which autobiographical memory is a phenomenon that is in between the personal and the interpersonal/social.  Autobiographical memory is to some extent a story with a number of authors, a story that is influenced by values and norms of the culture we live in.

In order to overcome such issues the authors let judges who were blind to the person's group affiliation have a qualitative impression of the memory.  The judges did get the impression that the memory quality of the three SDAM people for events that occurred not only during childhood and adolescence, but also ten years or one year or one week before was poorer (in terms of the richness of the memory and the extent of reference to events that happened before and after the main event) than the memory quality of the control group.

Neurologically, the three SDAM people had smaller right hippocampuses than the control group.  During recall of episodic events under fMRI, SDAM people had less activity in brain areas related to autobiographical memory and visual memory.

To sum up, we've seen evidence for the possible existence of a group of people who can't remember events from their lives, who have no episodic memory.  These are healthy, educated working people that are highly functioning cognitively and interpersonally.  Due to the small size of the group it's hard to tell whether their poor visual memory characterizes other people with SDAM.  Generally, it's hard to come to any conclusions on the basis of a group of three people.  A larger study is being currently conducted.

These findings are thought provoking.  We are used to think about our life story as an essential part of our selves, and of autobiographical memory as an essential part of our selves.  But these people definitely have a self concept, personality, hobbies, values, beliefs, opinions and friends.  They know who they are.

Furthermore: the ability of these people to function so well in everyday life in all respects – professionally, personally – raise the question: to what extent is episodic memory essential? And if it's not essential – why did it develop?

       

Palombo, D. J., Alain, C., Söderlund, H., Khuu, W., & Levine, B. (2015). Severely deficient autobiographical memory (SDAM) in healthy adults: A new mnemonic syndrome. Neuropsychologia, 72, 105-118.‏ http://www.sciencedirect.com/science/article/pii/S002839321500158X

The strange case of the woman who couldn't remember her past – and can't imagine her future.  Erika Hayasaki.  WIRED.

https://www.wired.com/?p=1994722

Can episodic memory be a (narrow) cognitive ability?

Shing, Y. L . et al. Episodic memory across the lifespan: the contributions of associative and strategic components.Neuroscience and Behavioral Reviews, 34 (2010) 1080-1091http://www.sciencedirect.com/science/article/pii/S0149763409001687

Episodic memory is memory for life events that we experienced in a specific place at a specific time.  Autobiographical memory is composed of episodic memory and semantic knowledge about ourselves and about things that took place in the world during our lifetimes.

Can episodic memory be a (narrow) cognitive ability?  Maybe so!  To do that, episodic memory has to fulfill a few conditions suggested by Schneider .  In this post we will discuss one of these conditions:  developmental across the lifespan.

All cognitive abilities identified hitherto (Fluid ability, Comprehension Knowledge, Processing Speed etc.) develop across the lifespan.   What about episodic memory?

Shing and his colleagues argue that the ability to remember lifetime events as personal experiences begins at about the age of six.  Episodic memory continues to improve from age six to adolescence, and deteriorates in elderly people.

There are different ways to recall life events (like the ways we retrieve semantic knowledge):  recognition ("Have you been to the Eifel tower?"), free recall ("Which sites in Paris did you visit?"), or cued recall ("Did you visit places in Paris from which there is a panoramic view?")

Recognition is the easiest form of remembering.  It requires less cognitive effort of searching in memory.  Free recall and cued recall require more cognitive effort and strategies for retrieval of information from memory.  Recognition develops in children at an earlier age than retrieval and cued recall.   Older adults show poorer performance than younger adults on memory tasks, with the difference in performance being largest in free recall, followed by cued recall and recognition.

 When we attempt to retrieve information from episodic memory we have to be able to discriminate between events we know had happened (but we did not experience them, since they did not happen to us personally), imagined events, and events that we'd actually experienced.  In other words, we have to be able to determine the source of the memory (something someone told us, something we imagined or something that happened to us).   We determine the memory source by retrieving contextual information from memory (what we did before and after the event, who else was there, what the physical environment in which it took place looked like etc.)

Children under six are poor at judging whether they imagined a specific activity or really performed it.  Old people are also poor at judging the source of memory.

Another distinction is between  recollection and familiarity.  There are events that we know happened to us, but we don’t experience them as episodic memory.  We don't have an experience of ourselves in these events.  We are familiar with these events but don't recollect them.

 The development of recollection extends into adolescence, whereas familiarity matures earlier during childhood.  When old people retrieve episodic memories, they rely more on familiarity and less on recollection.  They remember less specific details of the event, experience themselves less in the event itself, but can tell about the event since they are familiar with it and know they experienced it.

Strategies for organizing and retrieving episodic memories develop throughout the lifespan.  Coginitive control processes, such as elaborating and organizing the memory content, validating it with contextual knowledge, controlling the memory content (what content belongs to which event), creating a search strategy for a specific event in autobiographical memory– all these are active both during encoding and during retrieval.  Children younger than 6 are poor at organizing the memory content, even when they are instructed to do so.  Only by the end of elementary school, children begin to organize information they learn without being prompted to do so, and to activate strategies for memory search and retrieval.  Older people are poor at activating efficient strategies both during learning and during encoding and retrieval.

To summarize, we see that episodic memory is present by the age of six and deteriorates in old age.  Young children and old people have difficulty identifying the memory source more than adolescents or adults.  Small children and old people rely more on familiarity than on recollection when they recall episodic memories.  Efficient strategies for storage and retrieval develop during elementary school and deteriorate in old age. 

This is how episodic memory fulfills one of the conditions for being a cognitive ability – a pattern of development across the lifespan. 

Does it satisfy other conditions?  I hope to write about that in the future.

The strange case of the woman who couldn't remember her past – and can't imagine her future.

The strange case of the woman who couldn't remember her past – and can't imagine her future.

כתבה מעניינת מאד על חיים ללא זיכרון אפיזודי.   

הכתבה מתוך האתר המעניין כשלעצמו:   

SDAM– SEVERELY DEFICIENT AUTOBIOGRAPHICAL MEMORY

The Development of Autobiographical Memory

The Development of Autobiographical Memory. Robyn Fivush.   Annual Review of Psychology  2011.62:559-582.

http://www.psychology.emory.edu/cognition/fivush/lab/FivushLabWebsite/papers/Fivush2008AnnualRev.pdf

Autobiographical memory is defined as a sense of a self as continuous in time, linked across specific experiences, placed on a personal timeline that stretches back into a personal past, linked to the present and projected into the future.

This interesting paper assumes that autobiographical memory is a cultural activity.  In TULVING'S familiar conceptualization, episodic memory (memory of life events that are stored with reference to the place and time of their occurrence) and autobiographical memory are one and the same.  Fivush argues (not in a very convincing way I must say) that it's possible to distinguish between episodic and autobiographical memory.  I won't elaborate on this point, and focus on other interesting things in this paper:

The culture in which we live defines a "culturally canonical biography" or a "life script" –   how a life typically unfolds in terms of specified events at specified developmental points  (for example, school, college, marriage, children etc.).  Our culture's typical narratives and schemes shape the way we remember our personal past.  Autobiographical memory defines the self, and the present self defines which life memories will be more, or less, accessible.

Autobiographical memory is formed by reminiscing about an event with people that witnessed the same event and also by telling about events to people that did not witness them.  The act of telling about the event, and the active participation of others in the act of telling, shapes the way the event is remembered.  Reminiscing allows us to compare the way we remember an event to the way others remember the same event.  Through shared reminiscing, children learn to form a coherent narrative that creates a personal timeline linking past events and thus defining the self.

Apparently, there are significant differences in the way mothers talk with their preschool children about events they both shared.  Some mothers tend to elaborate, asking open ended questions and encouraging their child to recall more details about the event.  They lead the child through the event and help him remember details while weaving the details they remember and the details the child remembers into a coherent story.  Mothers with a less elaborate style focus on specific details and ask their child yes/no questions.  They don't help the child unfold the whole story.

By age 5-6, children of  elaborative mothers tend to tell narratives that are more detailed and coherent about their experiences.  By age 12, these children have first memories from a younger age than children of non elaborative mothers.  This is important, since people who can create coherent life stories are mentally healthier.

When non elaborative mothers were trained to elaborate, they succeeded in doing so even months after training.  As a result their children began to tell narratives that were more elaborate and more coherent.

Apparently, mothers and fathers are more elaborative when reminiscing with their preschool daughters than with their preschool sons.  By age 5-6, girls tell longer, more detailed and more coherent narratives than boys.

Autobiographic memory begins to emerge by the end of the preschool years, but fully consolidates in adolescence and early adulthood.  This is related to the development of understanding of time concepts.  Two - three year olds use the word "tomorrow" to refer to any event in the future and the word "yesterday" to refer to any event in the past.  Preschool children can accurately judge which of two events happened in the near or far past only if both events happened relatively recently.  If the events happened more than a few months ago, even 8 year olds have difficulties judging which event preceded the other.

The development of autobiographical memory is also related to the ability to link the present self with the past self.  This ability begins to develop around age 5.  In order to study this, researchers engaged children in play and surreptitiously placed a sticker on their head during the interaction (I hope the sticker didn’t stick too hard…).  They then showed the children a videotape of themselves in the playroom with a sticker on their head, either immediately after the play session or a few days later.  Three-year-old children did not make the connection between their depiction on the videotape and the sticker at all. They simply did not reach for the sticker. Four-year old children did reach for the sticker, but they did so regardless of when they were in the playroom. Even a few days later, they immediately reached for the sticker, assuming it is still on their head. Only at age 5 did children begin to understand the temporal connection between past and present self: If shown the videotape immediately after the play session, they reached to remove the sticker; if shown a few days later, they pointed and laughed but indicated that they were aware that it was in the past and the sticker is no longer on their head. Thus, it seems that it is only by the end of the preschool years that children are able to make temporal connections between the past and present self.

In another study, researchers asked preschoolers to predict how a child might behave in a certain situation (e.g., reactions to a new dog encountered in the park). They then told children about previous experiences of particular children (e.g., this child met a dog that frightened him). They then asked the children to link together these stories with predictions about behavior in the present. Children under the age of 5 had great difficulty with these tasks. Regardless of the stories told about specific previous experiences of specific children, they continued to predict that the child will eagerly approach the dog. At about age 5, children began to link up the past and the present; they predicted that this specific child will be afraid of the dog  and they were able to explain their predictions by linking previous experiences to the present through mental states that persist through time.