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. 

Episodic and Semantic Memory

Dr. Mark A. Gluck, Professor of Neuroscience at Rutgers University

 

https://www.youtube.com/watch?v=9-2s_7YvDq8

הרצאה מצוינת!  דר' גלוק מציג חומרים מעניינים, ומציג אותם בדרכים מעניינות ובצורה ברורה, בהרצאה זו על זיכרון סמנטי ואפיזודי.

A great lecture!  Dr. Gluck presents interesting findings in interesting and clear ways, in this lecture about episodic and semantic memory.

What makes learning, storage and retrieval more efficient?

Bjork, R. A., Dunlosky, J., & Kornell, N. (2013). Self-regulated learning: Beliefs, techniques, and illusions. Annual Review of Psychology, 64, 417-444.‏ http://cognitrn.psych.indiana.edu/rgoldsto/courses/cogscilearning/bjorkdunlosky.pdf

Here are insights from this interesting paper (with a few additions by me):

We do not store information in our long-term memories by making any kind of literal recording of that information, but, instead, we do so by relating new information to what we already know. We store new information in terms of its meaning to us, as defined by its relationships and semantic associations to information that already exists in our memories.  Storing information in human memory appears to create capacity—that is, opportunities for additional linkages and storage—rather than use it up.   I'll add, that when a piece of information is tied to a broader net of ideas and concepts, it is learned better.  This is why people with a broad knowledge base and good fluid abilities (that help them conceptualize links between new and old pieces of information), have an advantage in learning.

When we retrieve information from memory, we do not retrieve an exact "recording" of this information as it existed when it was learned.  We re-edit the memory.  When we recall an event, for example, we integrate features of the event with our assumptions, goals or experiences.  I'll add, that the manipulations we perform on the information we retrieve, like telling it or writing it down, also cause it to be re-edited and then later re-stored in memory as slightly different.  The context in which we retrieve the information also changes it and adds aspects that were not in the information at the time it was first stored.

The mere act of retrieval strengthens the information retrieved, so it becomes easier to retrieve it later.  Thus, when we study for a test, it's better to test ourselves and to retrieve the information from memory than to re-read it time and again.  The mere act of retrieval of specific information weakens our ability to retrieve similar competing information, which is tied to the same retrieval cues or semantic associations.  This phenomenon is called "retrieval induced forgetting".

We learn and retrieve information better when we introduce difficulties and challenges to the learning process.  Self testing (as opposed to passive rehearsals of the information) is an example of such a "desirable difficulty".  Self testing not only makes sure that we studied the information.  It is a part of the learning process itself.  When we answer a question on a self test, we reorganize the material and elaborate it.

Meta-cognitive monitoring and control are important parts of the leaning process.  During learning we evaluate the situation and make decisions, like what to learn next, how to learn it, whether we've learned enough for the information to be retrieved, whether we retrieved the information correctly, and so on.

It's recommended to space learning sessions across days, rather than to cram it in one session.  It's better to study two or three subjects simultaneously and to alternate between them ("interleaving"), than to study only one subject in depth.  When we study one subject in depth, processing is easier and more fluent than when we alternate between two subjects .  This is because when we massively study one subject, we hold the same concepts in working memory.  When we alternate between subjects, we need to re-retrieve the concepts of each subject that we alternate to from long term memory to short term memory.  The act of retrieval helps to learn them better.

In an experiment, participants were asked to answer trivia questions. The participants were told that they would be tested later, and the nature of the test was made very clear: They would be given a blank sheet of paper and, without being asked the questions again, they would be asked to free-recall the answers. During the question answering phase, after each correct answer, the participants were asked to predict the probability that they would be able to recall the answer again on the final test. The results were surprising: The more confident participants were that they would recall an answer, the less likely they were to recall it. This outcome occurred because participants predicted they would be able to recall the answer to questions that they answered quickly, but they were most likely to free-recall answers that they had thought about for a long time.  This means that efforts to process the questions and look for the answers in memory strengthened learning and increased the likelihood of retrieving the information later.  

In another study, researchers presented to participants paintings by 12 different artists. Some artists’ paintings were presented on consecutive trials while other artists’ paintings were presented interleaved with other paintings. As a test, participants were asked which artist painted each of a set of previously un-presented paintings. They were more accurate following interleaved (i.e., spaced) learning than following blocked (i.e., massed) learning. Blocking may have made it easier to notice similarities within a given artist’s paintings, whereas the value of interleaving appears to lie, at least in part, in highlighting differences between categories.  The comparison process causes the mental representation to be more abstract, with conceptualization of the categories of the differences and the relations between them. 

In the domain of motor skills there is substantial support for the idea that interleaving practice on separate skills to be learned, such as the several strokes in tennis, requires that motor programs corresponding to those skills be repeatedly reloaded, rather than executed over and over again, which has learning benefits.

The authors recommend designing textbooks that don’t mass one topic at a time but periodically return to prior topics in an effort to promote spaced learning.

What about mistakes and errors made during learning?  Anticipating, unsuccessfully, a to-be-learned response can enhance learning.  If participants are asked to predict what associate of a given cue word (e.g., Whale) is to be learned before they are shown the actual to-be-learned target (e.g., Mammal), their later cued recall (e.g., Whale: __?__) of the target word is enhanced, versus a pure study condition (e.g., Whale: Mammal), even when the predicted associate  differs from the target associate.

Making errors is often an essential component of efficient learning.  Manipulations that eliminate errors can often eliminate learning. Thus, for example, when retrieval of to-be-learned information is made so easy as to insure success, the benefits of such retrieval as a learning event tend to be mostly or entirely eliminated.  Introducing desirable difficulties into learning procedures, for example, such as variation or interleaving, tends to result in more errors being made during the acquisition process, but it also tends to enhance long-term retention and transfer.   Making  errors appears to create opportunities for learning and, surprisingly, that seems particularly true when errors are made with high confidence.  Feedback was especially effective when it followed errors made with high confidence versus errors made with low confidence.

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.

Does the state of our cognitive abilities affect the self?

A lot of our sense of self is embedded in our autobiographical memory – the memory of our life event, our "life story".  People usually don’t remember events that happened prior to the age of 4, and remember more events from the last 5 to 10 years of their lives.  People also tend to remember more events from the period when they were between the ages of 10 to 30 than from other periods of their lives. 

 Why?

 New and unique events happen in adolescence and early adulthood, among them events that are important for our self identity.   Due to their uniqueness, these events are kept in memory better.  They are also retrieved better, since they serve as examples to similar events encountered later in life.  This phenomenon of more memories between the ages of 10 to 30 has a cognitive explanation as well:  the cognitive systems and the memory systems (like working memory and long term memory) function optimally at this period of time.  That's why storage and retrieval of memories formed at this period is better.

The cognitive explanation for the phenomenon of more memories in the age range of 10-30 is related to the basic systems approach to autobiographical memory.  This approach argues that autobiographical memory depends on other cognitive systems since it involves the senses (the memory of an event involves sights, smells, tastes, sounds and touch) as well as language and emotions.  A deficiency in one of the cognitive systems will lead, according to this approach, to a deficiency in the content of autobiographical memory.

What do we know about success in verbal and visuospatial memory tests?  Women outperform men on verbal memory tests, while males outperform women on visuospatial memory tests.  Higher educated people succeed more on verbal and visuospatial memory tests than lower educated people.  Adolescents and young adults perform better on these tests than middle aged adults, and middle aged adults outperform older adults.  Performance on visuospatial memory tests reaches a higher peak in adolescence and early adulthood and deteriorates more steeply in middle age and older adulthood than performance on verbal memory tests.

One way to measure autobiographical memory is to compare between retrieval of a personal event right after its occurrence and retrieval of the same event after a while.  This procedure is usually done with the aid of diaries.  As the time gap between the event's occurrence and its retrieval lengthens, retrieval deteriorates.  Retrieval is affected by the valence of the event, its frequency (if it's very frequent it will be difficult to distinguish it from other similar events happening before or after this event, and so it will be harder to remember this specific event), and the amount of reminiscence (how much the person recalled this event in the time period between its occurrence and the point in time when memory for the event is tested).

This research

The relation between verbal and visuospatial memory and autobiographical memory. 

Kristo, Rouw, Murre and Janssen

http://www.sciencedirect.com/science/article/pii/S1053810014001792

was performed, like many other recent studies, through the internet.  The researchers created an internet site which has various memory tests, among them verbal and visuospatial tests, as well as questionnaires about autobiographical memories.  The site is open for every person who registers and takes as many tests as he wishes, when he wishes.

617 people wrote in the internet site about a personal event that occurred in the three days prior to writing.  They wrote, according to the researcher's requests, about the essence of the event, who was involved, where and when the event took place and described one important and one unimportant detail of the event.  They also rated the event's importance and emotional importance and its frequency.  The same people also took verbal and visuospatial memory tests.  After a period of 2,7,14,30 and 45 days the researchers contacted the participants (by email) and asked them about the events that they had previously described.

People who performed better on verbal and visuospatial memory tests performed better on the autobiographical memory tests (remembered the events better) than participants of the same age group that did less well on the verbal and visuospatial memory tests.  The ability to remember the personal event was more strongly related to the scores on the verbal memory tests than to the scores on the visuospatial memory tests.  The researchers suggest that a possible reason for this is that they did not ask visuospatial questions about the personal event (not at the time of writing nor at the later time).  Focusing attention on visuospatial aspects of the event might have contributed to a stronger relation between visuospatial memory and memory of the event.

What do sentence recall tests measure?

In sentence recall tests, the child listens to one sentence and tries to repeat it as precisely as he can.  Usually, the sentence's length and complexity grow as the test progresses.

This test is usually thought of as measuring memory span.  Memory span, in CHC theory, is a narrow ability within short term memory.  Memory span is "the ability to encode information, keep it in immediate awareness and produce it immediately in the order in which it was presented."  Or, put another way: "the ability to attend to and immediately recall temporally ordered elements in the correct order after a single presentation."  (Flanagan et al.,2007, Schneider and McGrew, 2012 ). 

Sentence recall is also an efficient marker of SLI – Specific Language Impairment and of dyslexia.  Performance in sentence recall tests is also related to reading comprehension.

A few researchers, including Baddeley, suggest that the sentence recall task involves short term memory as well as long term memory.  Sentence recall requires using general information, semantic knowledge (that help us understand what the sentence is about - the 'gist' of the sentence), and grammatical and syntactic knowledge.  Utilizing these knowledge types requires the involvement of long term memory.   The sentence recall task also requires keeping track of the structural aspects of the sentence ("keeping" the word order in the phonological loop, for example).  This involves short term memory.

Gathercole found in 2005, that people with high phonological memory are able to retain the word order in sentences much better than people with low phonological memory.  People with low phonological memory have more errors of omissions  and insertions  (they add and/or delete words from the sentence).  Sentence recall tests are correlated with nonword repetition tests, which are influenced by memory span.

Marshall and Nation found in 2003, that children with normal levels of reading accuracy and speed but low reading comprehension, also have low sentence recall.  These children have no difficulties in memory span tests.  The researchers suggest that the low performance in sentence recall tests is related to long term memory's involvement in sentence recall tasks.

In this study:

The role of sentence recall in reading and language skills of children with learning difficulties.  Alloway, T.P. and Gathercole, S.E.  learning and Individual differences, 15 (2005) 271-282

http://www.academia.edu/2651151/The_role_of_sentence_recall_in_reading_and_language_skills_of_children_with_learning_difficulties

participated children in elementary school with learning difficulties.  They were tested with reading, language, working memory, expressive vocabulary and sentence recall tests and the Wechsler test.  The hardest items in the sentence recall test were not longer sentences but were more complex sentences.  The goal was to see whether the sentence recall test is related to reading or to language skills.

A correlation of 0.6 was found between sentence recall and memory span.  But, when the unique contribution of each factor to the prediction of reading and language skills was examined, it was found that sentence recall explained a significant amount of the variance in reading and language skills above the contribution of age, IQ, expressive vocabulary, memory span and working memory.

So, sentence recall test measures much more than memory span.  Gathercole and Alloway suggest that sentence recall predicted performance in reading and   language tests because    sentence recall tests requires the use of both short term memory and linguistic and conceptual knowledge found in long term memory. 

Intelligence and cognitive abilities – Long term storage and retrieval

Intelligence and cognitive abilities – part six:

Long term storage and retrieval

is found here.

Memory is a very wide topic.

I've tried to focus here mainly on CHC conceptualizations of long term storage and retrieval, with minimal additions.