Educators educating Educators

Jan 25

Short-term Memory


Think of your memory bank as a board, the information to be stored in your memory as nails to be driven into the board, and your attention as the hammer to be used to drive the nails into the board.  If your attention is inconsistent, nonexistent, or if you are overloaded or if you are multitasking, many of those nails will not be hammered in correctly, if at all.  The nails will fall out; likewise, the information will fall out and not be stored in your memory.

~ a metaphor used by Ed Hallowell explaining the direct correlation between memory and attention ~


***  Teaching Suggestions  ***



Update January 19, 2011

Do you know how long the average student’s attention span is? Any idea what is “The Primacy-Receny” Effect? How about the varying levels of attention depending on the method of instruction? Know the 5 strategies to help children remember? Does plasticity and neurogenesis play a role in education? Finally, how about the 10 Guides to Better Teaching based on the latest neuroscience research?

Not sure of the answers? Then check out the Ming, Brain, & Education science section of this site. Tracey-Tokuhama-Espinosa has produced remarkable research to support her neuroscience-based Scientifically Substantiated Art of Teaching. It is a must read for all teachers desiring to stay current with cutting edge teaching pedagogy.

After investigating the Mind, Brain, & Education science information, return to this section and delve into supplementary information and research that support pedagogy based on educational neuroscience.



1. Activate stored (encoded) knowledge prior starting a new topic – Anticipatory sets

Accessing and activating prior knowledge is important because it helps students make connections to the new information they will be learning.  By tapping into what students already know, teachers can assist students with the learning process

According to noted learning theorist Jean Piaget, accessing prior knowledge is how children make sense of the world.  They attempt to take new information and fit it into existing knowledge in order to create a schema, or mental map that fits into a specific category.  This makes the information more accessible because it is more memorable.  When they make connections, it allows them to find the information using this network.

Most of the problems you face are ones you’ve solved before, so you just do what you’ve done in the past.  For the vast majority decisions you make, you don’t stop to consider what you might do, reason about it, anticipate possible consequences, and so on.  You do take such steps when faced with a new problem, but not when faced with a problem you’ve already faced many times.

When faced with a unique problem or information, the brain analyzes the incoming information by comparing and contrasting (looking for similarities and differences) this knowledge with pre existing knowledge.  Activating prior knowledge allows the brain time to scan encoded information to construct meaning by using prior knowledge to interact with the unique, incoming information and better prepares the child for the upcoming topic.

The link below provides a short example why the use of schemas increases student’s understanding.

Other techniques to activate prior knowledge are concepts maps, KWLH technique, graphic organizer, teacher real life story or analogy, think-pair-share, a student’s link to a personal experience.

2. The brain is Associative and beware of False Memories

Read the following words.

thread, sewing, haystack, sharp, point, syringe, pin, pierce, injection, knitting


Now, without looking up, did you read the word syringe?

Did you read the word injection?

Did you read the word needle?

Most people would say the “needle” was on the list.  What you experienced was a real memory, but it is a false memory.

This is because memories are associative.  All of the words seemed to go together and “needle” seemed appropriate so you remembered it.

What is taken out of memory is not a Rolodex file card but a reconstruction of the past, but reconstruction is at the service of trying to make sense of the present.

What are the classroom implications of false memory?  The memory a child gives you back may be completely different than the expected one because they are associating to things you are not aware of.

3. Make the subject and information meaningful to students.

The following example will illustrate this concept.

Divide the class in half and ask group 1 to determine the number of letters that have diagonal lines in them and the number that do not.

Tell group 2 to think about the meaning of each word and rate the words on a scale of 1 to 10 based on how much they like the word.

Favorite words

The result.  The group that processes the meaning of the words always remembers 2 to 3 times as many words as the group that looked at the architecture of the individual letters.  The more meaning something has, the more memorable it becomes.  No kidding!

John Medina in his book Brain Rules uses the above example to explain that the more elaborately we encode information for learning, the stronger the memory.  When encoding is elaborate and deep, the memory that forms is much more robust than when encoding is partial and cursory.  We remember things much better the more elaborately we encode what we encounter, especially if we can personalize it.  The trick is to present information in a compelling fashion so that the audience does this on their own, spontaneously engaging in deep and elaborate encoding.

Odd!  Making something more elaborate means making it more complicated, which should be more taxing to a memory system.  But more complex means greater learning.

This is why the expression “drill and kill” is true.  If emotional meaning is not attached to incoming information, it is soon forgotten and the memory is not reinforced, becoming extinct.


4. Using two study sessions with time between the sessions can result in twice the learning as a single study session of the same total time length.

Employ this technique when presenting a new topic.  During the first 8 minutes of class, introduce the first half of a new topic.  Following the initial presentation, students complete a corresponding 5-minute activity.  Next, present the second half of the topic followed by a related review activity that encompasses the entire topic.

In Welcome to Your Brain, Sandra Aamodt and Sam Wang describe this phenomenon as spaced learning vs. cramming.  They explain that synapses (described below) can be maxed out or lose their ability to learn new information, which is called long-term depression or weakening of a synapse connection.  A way to avoid this is to utilize two study sessions vs. cramming hours for an exam.

5. Optimal use of time: It’s all in the design - lesson design that is!

The brain prefers a “pulse” learning pattern.

Focused [Diffused] Focused [Diffused] Focused

The best learning occurs when interrupted by breaks of 2 - 5 minutes for diffusion or processing.

How long is best for focused activity?  The age of the learner plus two minutes.

Young learners: 5 – 10 minutes

Adolescents: 15 -20 minutes

Adults: 20 -25 minutes

The above was presented by Sarah Armstrong at the Learning & Brain Conference May 2010.

6. Utilize chunking which is breaking up long strings of information into smaller bits.

In Welcome to Your Brain, Aamodt and Wang explain that "brains are pattern processors.  Words presented in a logical, organized, hierarchical structure are remembered at a 40% higher rate than words placed randomly.  Why is this true?  Researchers have shown that when we create associations between concepts, we enhance memory.  Our brains are pattern matchers, or pattern driven processors, constantly assessing our environment for similarities and differences, and we tend to remember things if we think we have seen them before."

No connections = no meaning.  The brain is continuously trying to make sense out of the world, attempting to determine what is meaningful in what it experiences.  Every encounter with something new requires the brain to fit the new information into an existing memory category, or network of neurons.  It is imperative for the brain to connect new content to prior knowledge.  If it can’t, the information will have no meaning and not be converted to long-term memory.  (Armstrong, May 2010)

A chunk is any coherent group of items of information that we can remember as if were a single item.  A word is a chunk of letters, remembered as easily as a single letter, but carrying much more information.  (Armstrong, May 2010)

Chunking is an example of presenting information in a logical structure.  Herbert Simon showed that the ideal size for chunking letters and numbers, meaningful or not, was three.  This may be reflected in some countries to remember phone numbers as several chunks of three numbers with the final four-number group broken down into two groups of two.

For example, if presented with the string: FACMHDTIWNEB people are able to remember only a few items.  However, if the information is presented in the following way: FAC  MHD  TIW  NEB, people can remember many more letters.

The same method can be used with numbers. 177620011941 can be chunked into 1776  2001  1941 that represents twelve separate digits-well beyond most people’s capacity-but only three easily-remembered chunks.  In both examples, people are able to chunk the information into meaningful groups of letters or numbers.

The number example above demonstrates our limitations in remembering the number of items we can remember in order.  George A. Miller, when working at Bell Laboratories, showed that the capacity of short-term memory was 7±2 items, which was the title of one of the most highly cited papers in psychology, “The Magical Number Seven, Plus or Minus Two: Some Limits on Our Capacity for Processing Information” published in 1956 in Psychological Review.  With the opening sentence, “My problem, ladies and gentleman, is that I have been persecuted by an integer,” Miller suggests there is a fixed capacity for humans to receive information.  Miller’s hypothesis was seven (plus or minus two) was the magic number that characterized people’s memory performance on random list of letters, words, numbers, or almost any kind of meaningful familiar item.  Modern estimates of the capacity of short-term memory are lower, typically 4-5 items.  Beyond this capacity, new information can “bump” out other items from short-term memory, which is one form of forgetting.

7. Use real-world examples when introducing a topic or explaining material.

The more a learner focuses on the meaning of the presented information, the more elaborately the encoding is processed, - an obvious but often overlooked concept.

How does one communicate meaning in a way that improves learning?  Use relevant real-world examples embedded in the information, peppering main learning points with meaningful experiences.  The more personal an example, the more richly it becomes encoded and it is remembered.

The following experiment demonstrates this principle.  A group of students reads a 32-paragraph paper about a fictitious country in three different formats.  One contained no examples, one contained one example, and the third contained two or three consecutive examples of the main theme that followed.  The results were clear: the greater the number of examples in the paragraph, the more likely the information was to be remembered.

Why do examples work?  They take advantage of the brain’s natural predilection for pattern matching.  Information is more readily processed if it can be associated with information already present in the learner’s brain.  We compare two inputs, looking for similarities and differences as we encode the new information.  Providing examples is the cognitive equivalent of adding more door handles to the door.  Providing examples make the information more elaborate, more complex, and therefore better learned.

Another way to look at this concept concerns trying to drive a piece of information into your brain’s memory system - make sure you understand exactly what this information means.  When you are trying to drive information into someone else’s brain, make sure they know what it means.

But beware of the negative corollary.  If you don’t know what the information means, don’t try to memorize the information by rote and pray the meaning will somehow reveal itself.  And don’t expect your students will do this either.

8. Use compelling introductions when presenting material for the first time.

Introductions are everything.  The events that happen the first time you are exposed to information play a disproportionately greater role in your ability to accurately retrieve it at a later date.  If you are trying to get information across to someone, your ability to create a compelling introduction may be the most important single factor in the later success of your mission.  For example in public speaking, it has been reported that you win or lose the battle to hold your audience’s attention in the first 30 seconds of a given presentation.

For an illustration of this concept, refer to the door-handle example below in Insights & Tidbits.

9. Review of information over an extended time rather than an intense short period of time.

The massed-spaced effect refers to the fact that humans and animals more easily remember or learn information when it is studied a few times over an extended period of time (“spaced presentation”), rather than studied repeatedly in a short period time (“massed presentation”).  For 911 and the birth of a child, you only need one trail to remember.  But that is not how the world works where you need events and information repeated to be remembered.  The phenomenon was first identified by Hermann Ebbinghaus in the 1885 and has been confirmed copious times since it’s discovery.

Practically, this effect suggests that "cramming" (intense, last-minute studying) the night before an exam is not likely to be as effective as studying at intervals over a much longer span of time.  For the classroom, the massed-spaced effect implies that review for tests should be gradual and extended over several days rather than crammed the day before a test.


***  Insights ***

Memory Overview


Emotions or repetition turns an experience into a long-term memory.  The memories of a salient or traumatic event, such as the September 11 terrorist attacks, and those of something we do repeatedly, such as ride a bike, are very difference.  The former, which are memories of facts, people, events, things, and unique experiences are known as explicit or declarative.  The latter, the memories of how to do things, are known as procedural or implicit: They are the things we do without having to think about them.

We remember the facts important to our lives and the tasks that we repeat frequently.  The rest of our daily experiences rarely become long-lasting memories.  In fact, we retain most information for only a few minutes or hours before it fades away.

Scientists have recently discovered that when a memory is recalled, it becomes sensitive to disruption and become fragile after recall for a limited time.

An event’s biological relevance makes it important.  We remember painful, aversive events so that we can avoid repeating them; we remember happy, advantageous experiences because they represent our best biological fit (such as the best sources of food and sex).  In other words, emotional events, whether god or bad, stay with us: the stronger the emotion, the longer lasting the memory.

“More than 100 years of work in both humans and animals have shown that a newly formed explicit memory remains in a fragile state for quite some time.  Indeed, if pharmacological or functional interferences of brain activity occur during or immediately after an event as a consequence of, for example, stroke, physical trauma, or behavioral interferences, a long-term memory of the event will not form.  A typical example is a car accident.  A person will not remember the details about what happened just before and around the time of the accident.  The fragility of memory is greater right after the event, or learning phase.  As time passes, the memory becomes more resistant to disruption.

The process that mediates this time-dependent stabilization of memory is known as consolidation.  The duration and anatomy of the consolidation process still is not fully understood.  Clinical studies of people have revealed that memory consolidation takes weeks to years and occurs while the information is proceeded by the part of the brain known as the medial temporal lobe.  However, once a memory has been consolidated, information storage seems to involve brain regions other than the temporal lobe, particularly cortical areas.

Research has shown that memory consolidation requires the activation of molecular and cellular pathways.  For decades, scientists believe that consolidation of explicit memories occurred through a single process of stabilization.  They hypothesized that the process of memory consolidation involves molecular changes during the first 24 hours, significantly engages the hippocampus and related brain areas for a few weeks to months, and later involves different brain regions in the cortex, at which point memory was considered consolidated and insensitive to disruption.  However, recent studies have challenged this hypothesis.

About 10 years ago, investigators revisited discoveries made in the 1960s.  They found that memories that were one day old or older, and thus resistant to biochemical interferences, became sensitive again to interferences if and only if they were recalled.  In short, recalling a memory makes it liable, or modifiable, for a few hours.  During this time the memory restabilizes in much the same way a new memory consolidates after learning.  Thus, a day after recall a memory is again stable and resistant to disruption.  This post-recall process of restabilization has been termed reconsolidation.”

Paraphrased and quoted from “Long-term Memories: The Good, the Bad, and the Ugly” by Cristina M. Alberini, Ph. D. Cerebrum: The Dana Forum on Brain Science, October 2010



Hermann Ebbinghaus

Hermann Ebbinghaus, a German psychologist born in 1850, is most famous for discovering the most depressing fact in education.

People usually forget 90% of what they learn in class within 30 days. Also, the majority of forgetting occurs within the first few hours after class.


Hermann Ebbinghaus

Ebbinghaus pioneered the experimental study of memory and performed the first real science-based inquiry into human learning. He is known for his discovery of the forgetting curve, the massed-spaced effect, and was the first person to describe the learning curve. All have been confirmed many times since.

Over the course of his adult life, Ebbinghaus developed a list of 200 nonsense words, consisting of three letters, each with a consonant, vowel, consonant; TAZ, LEF, RIN, ZUG, and then spent the rest of his life trying to remember lists of these words in varying combinations and lengths. He discovered that some memories are only for a few minutes and then vanish. Other memories persist for days/months, even over a lifetime. He also discovered that one could increase the life span of a memory simply by repeating the information in timed intervals. The more repetition of a given memory, the more likely it would persist. Spaced learning is greatly superior to cramming.

Ebbinghaus’ work did not separate memory from retrieval, the difference between learning something and recalling it later. But we now know the space between repetitions is the critical component for transforming temporary memories to persistent forms.

Ebbinghaus' GraphEbbinghaus Chart


Memory & the Hippocampus

Rita Carter explains in her new book The Human Brain that “memories are stored in fragments throughout the brain and are distributed throughout the brain. One way to envisage the pattern of memories in the brain is as a complex web, in which the threads symbolize the various elements of a memory that joins at the nodes, or intersection points, to form a whole, rounded memory of an object, person, or event.”

One benefit of such a distributed storage system is that it makes long-term memories more or less indestructible because if one part of an experience is lost, many others will remain.

If they were held in a single brain area, damage to that place would eradicate the memory completely. As it is, brain trauma and degeneration may nibble away at memories but rarely destroy them entirely. You may lose a person’s name, for example, but not the memory of their face.

Carter explains that “declarative memories are laid down and accessed by the hippocampus but are stored throughout the brain. Each element of a memory is encoded in the same part of the brain that originally created that fragment. When you recall the experience, you recreate it in essence by reactivating the neural pattern generated during the original experience that was encoded to memory. Once a memory is sparked off, the hippocampus triggers various aspects of it in unison and different brain areas recall a variety of memories.”

Take, for example, the memory of a dog or cat you once owned. Your recall of his color is created by the color area of the visual cortex; the motor area of your brain reconstructs the recollection of walking the dog; his name is stored in the language area, and so on.



Remembering information initially

The first few moments of learning give us the ability to remember something and the first few seconds of encoding determines whether something that is initially processed will also be remembered.

Elaborate rehearsal is the most effective means of robust retrieval. Thinking or talking about an event immediately after it has occurred enhances memory for that event. Law enforcement officers know this well and utilize this principle by having a witness recall information as soon as possible after a crime.

Why is elaborate rehearsal (repetition) important? Memories may not be fixed at the moment of learning, but repetition, doled out in specific time intervals, is the fixative. Research has shown that the typical human braincan hold about 7 pieces of information for less than 7 seconds. You need to re-expose yourself to the information, which is called maintenance rehearsal.

Ebbinghaus showed the power of repetition almost 100 years ago. He created forgetting curves, which showed that a great deal of memory loss occurs in the first hour or two after the initial exposure and demonstrated that this loss could be lessened by elaborate and deliberate repetition. Furthermore, the timing of re-exposure is critical.



Different types of memory systems

In their book Welcome to your Brain, Sandra Aamodt and Sam Wang write that we have 12 different types of memories or memory systems and all operate semi-autonomously. For instance, remembering your social security number is much easier than recalling how to ride a bike. The contrast proves a point: One does not recall how to ride a bike in the same way one recalls nine numbers in a certain order or one does not recall how to ride a bike in the same way one recalls numbers. The ability to ride a bike is independent from any conscious recollection of the skill. You were consciously aware when you were remembering your Social Security number, but not when riding a bike. Do you need to have a conscious awareness in order to experience a memory? According to Aamodt and Wang, no.



Types of memory

There are different types of memory: Short-term, Long-term (discussed briefly here but also under separate listing), Working, Explicit or Declarative, and Implicit or Procedural.

Short-term memory

Psychologists and researchers now believe that short-term memory is a collection of temporary memory capacities, each capacity specializes in processing a specific type of information, and each operates in parallel fashion with the others. As a result of this theory, short-term memory is now called working memory by some researchers/writers to reflect this multifaceted talent but I still consider them separate and distinct memories.

Short-term memory is placing menial demands on the brain for processing and is often described as storage-only tasks. For instance, one remembers a phone number and immediately forgets it after dialing the number.

There are two types of short-term memory: verbal short-term and visual–spatial. Verbal short-term is assessed using tasks that require the participant to recall a sequence of verbal information, such as a digit span and word span. Visual-spatial short-term memory tasks usually involved the retention of either spatial or visual information.

Long-term memory

Example of short & long-term memory.  Long-term memory is parking your car at the supermarket and short-term memory is remembering the quart of milk you intended to buy.  The difference between the two memories is how the brain stores the information.  Location of the car is stored in your long-term memory.  Note that no neurons in the frontal lobe are encoding the car’s location or are continually active therefore the memory becomes extinct.

The item you are looking for, the milk, is stored in your working memory.  This information is “online,” in that it is constantly in your consciousness in a way that corresponds to the uninterrupted activity of certain frontal lobe neurons.  How do the neurons remain active during this delay is a mystery.  One hypothesis, the presence of recurrent loops, neuronal networks that keep the activity going by stimulating each other.

Working memory

Working memory was a pioneering concept introduced by leading neuroscientists like Alan Baddeley and Patricia Goldman-Rakic, but it has since undergone many alterations.

Working memory is a busy, temporary workplace; a desktop the brain uses to process newly acquired information. It is the type of memory that enables you to spit back the last sentence of a conversation and is critical for performing some common operations in your head: adding numbers, composing a sentence, following directions, etc. The space devoted to that operation is recycled as soon as you turn to something else; therefore, the information does not become permanent memory.

Working memory is defined as the ability to keep information active for a short period of time based on continual neuronal activity. Working memory is used to control attention, to remember instructions, to keep in mind a plan of things to do, and to solve complex problems and is located in the frontal lobes.

Working memory is the ability to hold information in your head and manipulate it mentally. You use your workspace when adding up two numbers spoken to you by someone else without being able to use a pen and paper or a calculator or to remember a phone number and then mentally add the phone numbers.

Children at school need this memory on a daily basis for a variety of tasks such as following teacher’s instructions or remembering sentences they have been asked to write down.

Patricia Goldman-Rakic, a Yale neuroscientist, invented the Dot test and demonstrated information is retained in working memory when a certain pattern of neurons is continually active. Called delay-period activity, cells were active when a monkey looked at a dot it was to remember and continued to send an uninterrupted current of signals even when the dot disappeared. But when the monkey shifted its attention, the current stopped and the monkey would no longer be able to remember the information. She found this activity is located in the parietal and frontal lobes.


This process is much more dynamic than long-term memory in that it provides an immediate means of storage of information, since patterns of electrical activity can be established in a matter of milliseconds. However, it is a sensitive means, since the memory will be lost once the network is disrupted and the continual surge of activity is terminated.

In his book Brain Rules, John Medina describes working memory as a three-component model consisting of auditory, visual, and executive components. Auditory memory allows us to retain some auditory information, and is assigned to linguistic information, which is referred to as the phonological loop. Visual memory allows us to retain some visual information, and is assigned to any images and spatial input the brain encounters and referred to by Braddely as the visuo-spatial sketchpad. The prefrontal cortex, the central executive, is the controlling function, which keeps track of all activities throughout the working memory.

All have two important characteristics: limited capacity and limited duration. If the information is not transformed into a more durable form, it will soon disappear.

Tracy Alloway discussing Working Memory

At the April 2011 daylong symposium at Columbia University in New York City on the topic “Memory and Mind: Improving Memory and Achievement in the Classroom, Tracy Alloway, director of the Center for Memory and Learning in the Lifespan at the University of Stirling, United Kingdom, discussed the working memory and its relation to reading achievement. Alloway described working memory as the cognitive ability to handle multiple pieces of information simultaneous, such as to add numbers or pick out rhyming words. Alloway says “brain imaging research shows that during a working memory task, the prefrontal cortex is working hardest.”

Working memory skills develop through childhood, reaching adult levels around age 16. “But at any age there’s a huge range, Alloway said. “In a group of 10-year-old olds, some may look like average 5-year-olds, some like 15-year-olds.”

“The faculty is the foundation of learning,” she said: it determines the capacity to process information, follow instructions, and met classroom demands. Working memory predicts academic achievement far more robustly than IQ, and is less influenced by socioeconomic status.

For an example of the limitations of working memory, take the Stroop effect experience.

The famous "Stroop Effect" is named after J. Ridley Stroop who discovered this strange phenomenon in the 1930s. Here is your job: name the colors of the following words. Do NOT read the words...rather, say the color of the words. For example, if the word "BLUE" is printed in a red color, you should say "RED". Say the colors as fast as you can. It is not as easy as you might think!

Stroop Task Easy

Easy? Now try the next one. Warning, it will quickly become harder.

Stroop Task Hard1

The words themselves have a strong influence over your ability to say the color. The interference between the different information (what the words say and the color of the words) your brain receives causes a problem.

Stroop effect experience is called interference. When you look at the word, you see both their color and their meaning. When these are in conflict, you have to make a choice. Because experience has taught you that meaning is more important than ink color, interference occurs when you try to pay attention to only color. Your working memory has to tell you to avert your attention from the meaning of the word and concentrate instead on the color.

The point being is that you are not always in complete control of what you’re paying attention to.


Although I have never tried it, I think that this puzzle would be easier for a very young child than for older children or adults.  A child who has learned the names of colors but cannot read probably would have no problem with the Stroop effect experience since the words do not have any meaning, the child’s attention would be on the color of the word.

Explicit/Declarative memory

The second type is what we most commonly associate with “memory”. This is long-term or explicit/declarative memory, and is composed of all the facts, figures, and names you have ever learned. All of your experiences and conscious memory fall into this category. Scientists differentiate between two types of explicit/declarative memory. Semantic memory is about information not related directly to people, locations, or time: it’s generalized or factual information without (necessarily) specific content, such as the multiplication tables. Episodic memory is about experiences relating to the self and it is the very heart of autobiographical memory, which forms the foundation of the self and self-awareness. According to Judith Horstman in The Scientific American Day in the Life of Your Brain, the hippocampus is responsible for episodic memory, and the surrounding cortex controls semantic memory. Although no one knows exactly where this enormous database is stored, it is clear that the hippocampus is necessary to file away new memories as they occur.

Implicit/Procedural memory

The third type of memory is implicit/procedural memory, and is probably the most durable form of memory. These are actions, habits, or skills that are learned simply by repetition. Examples include playing tennis, playing an instrument, solving a puzzle, etc. The hippocampus is not involved in procedural memory, but it is likely that the cerebellum plays a role in some instances.


Too little memory: The patient named H.M. (Henry Gustav Molaison, February 26, 1926 – December 2, 2008) who lost his ability to remember new things



For a fascinating discussion of memory, it is helpful to look at the famous patient referred to as H. M. who has been studied for more than 40 years by Brenda Milner, a psychologist.

H.M., born in 1926, suffered a severe head injury that left him with epileptic seizures, which got worse with age, culminating in one major seizure and 10 blackouts every 7 days. In 1942, H.M. at age 16 had his first major seizure, and by his late 20s, H.M. was dysfunctional, of great harm to himself, and in need of dramatic intervention.

In 1953, the famed neurosurgeon William Scoville removed the inner surface of the temporal lobe (brain region located right behind eras) on both sides of the brain. This greatly helped the epilepsy, but left H.M. with catastrophic memory loss.

Following the surgery, H.M. lost the ability to convert a new short-term memory into a long-term memory. He could not encode new information. H.M. could meet you twice in two hours, with no recall of the first meeting. He lost the conversion ability Ebbinghaus described 50 years before.

Additionally, he could no longer recognize his own face in the mirror. Why? As he aged, the physical appearance of his face changed, but he could not process the new information and convert it into long-term memory. He was locked into a single idea about his appearance, and when he looked in the mirror, he could not identify to whom the aging image actually belonged.

At least two regions of the brain are involved in memory: the cortex and the hippocampus. The cortex is composed of 6 layers of discrete wafer-thin cells sitting atop the brain and about the size of a baby’s blanket. The cortex processes signals from all areas of the body including the sense organs and is involved in creating stable, long-term memories.

The hippocampus is near the center of the brain, in each hemisphere, and is involved in converting short-term memories into longer-term memories. This is the region H.M. lost during surgery, which is needed for declarative memory.




Listen to Jon Medina, author of Brain Rules, explain H.M. surgery.

Brain Rules




Another person with too little memory


Imagine life without memory. View the link below of Clive Wearing, who lost his memory due to an infection of herpes encephalitis that wiped out his memory. Here’s a person whose life is a series of fragments without memory for 20 years of life, one night 20 years long with no dreams. There is no difference between day & night, no thoughts at all. In that sense, it has been totally painless, which is not something desirable, is it? Wearing shows us how memory is central to our existence. Without it, life is empty and meaningless.



Too much memory: Kim Peek (November 11, 1951 – December 19, 2009), the original Rain Man

Kim Peek

Kim Peek, a mega savant, could read a page of a book in ten seconds (about a book per hour), remembered everything he had read, can recall 12,000 books, does formidable calculations in his head, and remembered music he had heard decades ago. He is the only savant know who could read two pages of a book simultaneously – one with each eye, regardless of whether it was upside down or sideways on. His ability to retain 98% of the information he absorbed led to his designation “mega-savant”.

By the time he was nine-moths old he was expected to be mentally impaired for life. At age 16 months old, he taught himself to read children’s books. At age 6, his family was offered a lobotomy. His parents declined, and Kim went on to memorize the entire bible before his seventh birthday. Expelled on his first day for being disruptive (no special education laws at the time), he was home schooled. By age 14, Kim had completed the high school curriculum, though local authorities would not recognize the achievement and refused to award him a certificate

By the age 18, he read and memorized the complete works of Shakespeare and every story in every volume of the condensed Reader’s Digest books. He used the telephone directory for exercise in mental arithmetic, adding each column of the seven-digit numbers together in his head until he reached figures in the trillions. Kim had faultless knowledge of the calendar stretching back 2,000 years.

The five universities that studied him decided that he was a genius in at least 15 subjects when most savants reach a similar level in one or two subjects.

Kim’s head was 30% larger than normal at birth, which required support physical support because of its weight. As an adult, he had the mental reasoning of a child of five and was unable to dress himself, cook, shave, or brush his teeth without help. He walked at age 4 and in a sidelong manner, had impaired motor ability, had difficulty with abstractions, and below average intelligence (IQ=87); however, he scored very high in some subtests.

He was a sluggish baby who cried frequently, and doctors discovered he had a blister inside his skull that had damage the left hemisphere of his brain, which controls language and motor skills. In addition, he had damage to the cerebellum and absences of a corpus callosum - the connections between the two hemispheres.



So what happens at the moment of learning, of encoding?

To explain this phenomenon, Medina uses an example of a blender left running with the lid off. The information is sliced into discrete pieces as it enters the brain and is splattered all over the insides of our mind. Stated formally, signals from different sensory sources are registered in separate brain areas. The information is fragmented and redistributed the instant the information is encountered.

An example of this procedure is to examine the situation of a woman who suffered a stroke and lost her ability to use written vowels. As she wrote, there would be a place for every letter, but the vowels’ spots were left blank! This demonstrates that vowels and consonants are not stored in the same place, resulting in damage to her connective writing ability.

But it goes deeper. When she wrote the sentence, she perfectly preserved the place where the vowels should go. Logically, the place where a vowel should go is stored in a separate place from the vowel itself. Content is stored separately from its context/container.

How then do we keep track of everything? How do features that are registered separately become united to produce perceptions of continuity? It is called the binding problem.

To encode information is to covert data into a code. Creating codes always involves translating information from one form into another, usually for transmission purposes. From a physiological point of view, encoding is the conversion of external sources of energy into electrical patterns that the brain can understand. It organizes information for storage purposes and prepares information for further processing. Encoding involves transforming any outside stimulus into the electrical language of the brain, a form of energy transfer.

Encoding involves all of our senses, and their process centers are scattered throughout the brain. This is the heart of the blender. The brain recruits hundreds of different brain regions and coordinates the electrical activity of millions of neurons. This binding phenomenon keeps tabs on far-flung pieces of information and some researchers believe the hippocampus, the grand central station of memory, is one of the brain regions primarily involved in this process.



The door-handle example

In the past, stores had door handles at different heights. The logic was simple: the more handles on the door, the more access points that were available for entrance to a building, regardless of the strength, age, or height of the customer. Today, most commercial establishments have doors with elongated handles that accomplish the same purpose.

John Medina connects this analogy to encoding by explaining that the “quality of encoding means the number of door handles on the door.” He continues, “the quality of encoding really means the number of door handles one can put on the entrance to a piece of information. The more handles one creates at the moment of learning, the more likely it can be accessed at a later date. The handles we can add revolve around content, timing, and environment.”






The brain is Velcro sticky; it is an association machine, and a reason why mnemonics work. This is why we get jingles stuck in our heads and the reason why we say the ABCs or “Twinkle, twinkle little star.”

Can’t get a certain song out of your head? Certain phrases or songs that stay on your mind are examples of sequences. Sequences are important because they are used to recall remembering. We use sequencing to make coffee, to remember the names of exits, etc. Sequencing improves the likelihood you will remember an action or word, which then will lead to more reinforcement. It is necessary for normal strengthening and cementing of memories.

Why are certain sequences hard to get out of your head? Because they have an emotional impact or component to them. Emotion highlights the effect of the experience and makes it more likely to be consolidated in memory. How to break the sequencing or reinforcement? Thinking of another sequence, song, or phrase will crowd out the first one.



At the movies

In the movie Memento, Leonard is unable to remember what happened to him a few minutes ago due to brain injury. He had trouble learning new facts and events, which is a function of the hippocampus, the temporal lobes, and parts of the thalamus. The amygdala intensifies a memory by adding an emotional component to it.


Movie Menento



Happy New Year! I trust your holidays were refreshing and you are energized to begin the New Year. Possibly one of your resolutions was not only getting your body in better shape, but also your mind in tip-top shape.

For educators, a good place to begin implementing this New Year’s resolution to improve our minds is to review the basics of brain development and how it learns. Explore January 2015 News Update for more information on this topic.