There are two types of memory systems: the short-term memory system and the long-term memory system.   However, memory begins with sensory memory.

Sensory memory is very short, most times a fraction of a second to a few quick seconds.  Its purpose is to hold that sensory input for a very short time to make sure that you don’t need it.  You are talking to a friend.  Suddenly, they ask you something and you say, “What?”  Before they can ask you again, you have suddenly remembered what they said and you can reply to it.  This is your sensory memory.  

Sensory memory is the gateway to short-term memory.  When you pay attention to and perceive the sensory input, it moves to short-term memory.

Short-term memory is the memory type that processes what is happening in the here and now.  It acts as a kind of mental “scratch-pad” for temporary recall of information that is being processed at any point in time.  It has been referred to as the brain's “Postit note.”  The short-term memory holds a small amount of information (typically around seven items or less) in mind in an active, readily available state for a short period of time (typically from 10 to 15 seconds, or sometimes up to a minute or two) (Merzenich, 2013).  An example of this is happening right now.  In order for you to understand this sentence, your short-term memory needs to hold the beginning of the sentence in mind while the rest of the sentence is read, so that you can make sense of it. The same thing happens when you are listening to someone speak.  Imagine if you couldn’t remember the beginning of their sentence by the time they got to the end!   

Although we cannot expand our short-term memory, with practice, we can improve our ability to hold the information it is able to remember, so we can better use it.  It can also be improved by chunking information (breaking up long strings of information into units or chunks), or using specific coding tricks.  To test your own short-term memory, try this fun activity.

Short-term memory can be thought of as the gateway to long-term memory.  It is facilitated by two other types of memory--Sensory Memory and Working Memory.

The term working memory is often used interchangeably with short-term memory, although technically, working memory refers more to the whole theoretical framework of structures and processes used for the temporary storage and manipulation of information, of which short-term memory is just one component (Mastin, n.d.).  Working memory refers to the mental processes that keep memories in mind for a short time.    The working memory processes allows us to hold a memory briefly, such as a phone number, until we can write it down.  

Long-term memory is the memory type intended for storage of information over a long period of time.  Long-term memory actually decays very little over time and can store a seemingly unlimited amount of information almost indefinitely (Merzenich, 2013).  There is some debate as to whether we actually ever “forget” anything at all, or whether it just becomes increasingly difficult to access or retrieve certain items from long-term memory. 

Implicit memory, also known as non-declarative memory, is the system that allows humans to learn structures of everyday life, such as grammar, music, etiquette, and more.  When we encode these structures, we make predictions about future events (allowing us to act and respond in certain ways); it also helps us to notice events that do not fit into the patterns.  Implicit memory is encoded by repeated experience with some context without attempting to learn anything.   An example is musical genre.  Even if you have never heard a song, you can identify if it is blues, rock, or country.  

Implicit memory is sometimes referred to as unconscious or automatic memory.  It uses past experiences to remember things, no matter how long ago those experiences occurred.  Implicit memory allows us to remember things without actually thinking about them.  An example would be buttoning a shirt.  Implicit memory does not provide a clear answer, only a look at the structure which guides behavior.  

There is no particular context associated with implicit knowledge.  It works with explicit memory to further understand a memory or concept.  An example are medical students who begin to see patients after completing the academic part of their studies.  The patients will help the interns to develop an understanding of symptoms and illnesses to add to the interns' semantic memory of these same things.  

There are a few subsets of implicit memory—procedural memory and priming (Zimmerman, 2014a):

Explicit memory, also called declarative memory, involves a conscious attempt to retrieve memories of past events. Using explicit memory requires an effort to bring those memories to the surface.  It provides a clear answer to a question.  For example, while you might be able to easily name the days of the week (implicit memory), it takes explicit memory to recall that you have an appointment next Tuesday (Zimmerman, 2014a).  There are two sub-categories of explicit memory: semantic memory and episodic memory.

• Episodic memory is having a unique memory of a specific event, or when you review an episode from your life, like what you had for dinner.  An example of episodic memory is remembering where you were when you found out about the September 11, 2001 attacks at the World Trade Center and the Pentagon (Zimmerman, 2014b).  This type of memory relies on the context in which it was formed. 

As mentioned earlier, the human memory is complex and not yet fully understood.  However, through years of research and experimentation, we have a basic idea of how the brain creates, stores, and retrieves memories.  

By focusing our attention on sensory input, we have begun the process of creating a memory, which the brain now tries to make sense of.  Is that smell pleasurable?  Did you feel frightened by that visual scene?   Were several senses engaged at once?   All of this information needs to be taken to the brain, where it is encoded and processed.  At this point, we want to work closely with these memories to get them into short- term memory.  We want to find some way to link several different segments of the memory, in a process called consolidation.  Then we need to begin to retrieve the memory.  Think about it actively, try to recount the various ways that the memory was significant.  You find that the memory becomes stronger if it is combined in a variety of modes, such as visual and speech, or touch and smell. 

Sensory information will quickly disappear from the short-term memory unless we make a conscious effort to retain it.  Short-term memory is a necessary step toward the next stage of retention--long-term memory.  As you may suspect, it requires some work to take that initial sensory input and embed it into your long-term memory.  When we actively think of and interact with short-term memory, it is moved to long-term memory.  The transfer of information to long-term memory for more permanent storage can be facilitated or improved by mental repetition of the information or, even more effectively, by giving it a meaning and associating it with other previously acquired knowledge.   Long-term memory is improved when multiple systems in the brain are used to remember something. The key to keeping something in long-term memory is to practice frequent retrieval of information. Motivation is also a consideration, in that information relating to a subject of strong interest to a person is more likely to be retained in long-term memory.  We can say that short-term memory is the gateway to long-term memory. 

There are three phases in the process of helping your working memory create a long-term memory:

1. Getting the information into the short-term memory (pay attention to sensory inputs that you wish to remember--FOCUS!)

2. Handling the information appropriately while it is in the short-term memory.  You can do this by: 

     a.  Working with only small amounts of new information at a time.

     b.  Clearing out unneeded, old information from the working memory.

     c.  Chunking several pieces of information together.

     d.  Practicing "retrieval" by calling up the information repeatedly. 

     e.  Remembering dual coding (trying to encode each memory using multiple senses, like vision, speech, touch, etc.)

3. Moving information from short-term to long-term memory, through the processes of the working memory, and then using this information in a constructive manner (discuss it with a friend, take a test, write a paper, etc.).  

The process of memory consolidation, done by the working memory, takes place in the hippocampus, where memories are stored, and then transferred into long-term memory.  Encoding enables this transfer of information.  People tend to remember the beginning of things (also known as the primary effect) and the end of things (also known as the recency effect).  The beginning things spend the most time in working memory; the endings are remembered because they may still be in working memory. 

The reason was found to be that the taxi cab drivers used three types of long-term memory in their daily work tasks: a) Episodic = memories of street closures, traffic accidents, etc.; b) Semantic = memories of the thousands of streets of London; and c) Procedural = the memory of the act of driving; whereas, the bus drivers simply followed a pre-planned daily route, and didn’t need to use as many memory systems.  These findings should motivate us to use as many of our own memory systems as possible when analyzing a problem or performing a task, so we can improve our memories even more.

Through a process involving the creation of new proteins within the body of neurons, and the electrochemical transfer of neurotransmitters across synaptic gaps to receptors, the communicative strength of certain circuits of neurons in the brain is reinforced.  With repeated use, the efficiency of these synaptic connections increases, facilitating the passage of nerve impulses along particular neural circuits.  Forgetting occurs in long-term memory when the formerly strengthened synaptic connections in a neural network become weakened (Mastin, n.d.).

Let’s look at an example of how this might work.  When you look at a picture of a mug, for example, the neurons that store your memory of what a mug is begin firing.  A host of neurons that code for related ideas and items (bowl, coffee, spoon, plate, breakfast, etc.) are also activated.  Neuroscientists have found that the brain organizes ideas and words into semantically related clusters, which it activates when trying to recall a specific word. It is how the brain narrows this down to “mug” that Ries is studying (San Diego State University, 2017).  

Since the 1950s, it has been thought that all memories start as a short-term memory in the hippocampus and are then slowly converted into long-term memory in other parts of the brain.  In other words, the hippocampus collects short-term memories while the cortex retains long-term memories.  The discovery of multiple areas of memory storage was made when Henry Molaison, a man whose hippocampus was damaged as a result of surgery for his epilepsy.  He could no longer make new memories, yet, his memories from before the operation remained intact, supporting the theory that two parts of the brain are involved in collecting and storing memories (Donnelly, 2017).  

Research has found that memory may not be as fleeting as originally thought.  Specifically, procedural and semantic memory show little decline with aging, and may be more related to physical things (arthritis, hearing, vision).  Although episodic memory does show some decline, it may not be as much as originally suggested, as memory depends on the time of day.  For older adults, the best time of day is the morning, and not late afternoon (when these studies were originally performed).  As for the retelling of stories, it was suggested that this may actually be an evolutional process to retain our information from generation to generation.  The best ways to improve episodic memory are to use complex activities such as dancing, painting, writing, and lifelong learning. 

Learning a procedural task requires explicit instruction when there is a single right way to do something (such as performing a scale on the piano).  Constructivist learning is when we try to figure it out independently and in the context of what we already know to be true.  Constructivist learning encourages creativity and shows the multiple ways to interpret behavior.  

Scientists aren’t certain exactly how many people have mild cognitive impairment.  Estimates range from 1% to 26% of Americans 65+.  For some people, mild cognitive impairment represents a transitional period between the mild and manageable memory problems associated with normal aging, and the debilitating symptoms of Alzheimer's disease.  Estimates vary, but a number of studies suggest that about 10% of those with a specific type of memory-related mild cognitive impairment go on to develop Alzheimer's disease each year (Posit Science, n.d.; Posit Science, n.d.a).

Memory loss may be temporary or short-term.  With proper evaluation, care, and treatment, memory can be restored in many cases to its former strength. However, if you are experiencing frequent memory lapses, or others are mentioning that they notice a difference  in your memory, it is recommended that you visit your doctor.  Your doctor can provide a thorough physical exam to rule out any other medical reason for your memory loss.  A doctor can also refer you for a neurologic exam where your mental abilities will be tested and evaluated. Further evaluations could include blood and urine tests, nerve tests, or imaging tests (CAT scan, MRI, etc.).  

Treatment for memory loss depends on the diagnosed cause(s).  If the cause is deemed to be temporary and thus reversible, a single therapy or a combination of therapies can be effective (e.g. medication, supplements, counseling, exercise, diet).  If the issue may be more serious those and other treatments may be helpful.

Mnemonics are techniques to help remember information.  Try these and see which of them work for you.

Keyword:  For example, if you're trying to learn the Spanish word for cat, which is gato, first think of a gate and then imagine the cat sitting on top of the gate. Even though the "a" sound in gato is short and the "a" sound in gate is long, the beginnings are similar. Thus, the visualization and association should trigger the recall of the correct word.

Chunking: For example, 7603176688, could be 760.317.6688.  We remember phone numbers this way.

Music: For example, singing the A-B-C song.

Letter & Word: For example, My Very Educated Mother Just Served Us Nachos.  This is the order of the planets from the sun.  

Please Excuse My Dear Aunt Sally, is the order of operations in algebra.  Parenthesis, exponents, multiplication, division, addition, and subtraction. 

Rhymes:  For example, i before e except after c.

Making Connections: For example, imagine that you are just introduced to someone named Jeffery.

Rather than mentally zipping past his name, pay attention and think about how you can remember it. Perhaps you notice that Jeffery is very energetic, so you can imagine him jumping around his work and connect Jeffrey with jumping.

The next time you see him. you'll think, "There's 'Jumping Jeffery' and you can say hello by name."

Method of Loci:  For example, the learner visualizes a room or a familiar path through a building and mentally associates facts or information with specific locations or objects along the way.  In order to recall what is learned, a person re-visualizes moving through that room or along that path and each stop along the way triggers another piece of information.

This method is also called the journey method, creating a "memory palace" or the mental walk strategy.

Research ranging from medical students learning about diabetes to college students remembering grocery lists show significant improvements when the method of loci is used.

Peg Method: The peg method is an especially useful mnemonic for remembering sequenced information. If first requires that you memorize the following list in help you order the facts:

•        one = bun

•        two = shoe

•        three= tree

•        four = door

•        five = hive

•        six = sticks

•        seven = heaven

•        eight = gate

•        nine = vine

•        ten = hen

After you have memorized this list, look over the new information that you are trying to learn. Then, connect the first word to "bun," the second word to "shoe," the third word to "tree," etc. The goal is to make a memorable connection with each new piece of information you need to memorize.

For example, let's imagine you need to learn the scientific classification system - Kingdom; Phylum or Division; Class; Order; Family; Genus; Species. Using the peg system, you'll first think of a kingdom placed on a hamburger bun. Then, you'll imagine the mathematical division sign inside a shoe.

Next, you'll picture a classroom perched on a tree branch. And so on.

This method allows you to be able to recall both the specific piece of information as well as the correct order in which it needs to be placed.

Linking System:  For example, imagine that you need to remember to bring the following things with you to school in the morning: homework papers, glasses, gym shoes, wallet, lunch money, and keys.

Using the linking system, you can think of the following short story to help you: Jack's homework papers put on their glasses and gym shoes and ran over to his wallet where his hungry keys were eating his lunch money.

If you add interesting details or humor, it often makes the information easier to remember.

Linking System:  For example, imagine that you need to remember to bring the following things with you to school in the morning: homework papers, glasses, gym shoes, wallet, lunch money, and keys.

Using the linking system, you can think of the following short story to help you: Jack's homework papers put on their glasses and gym shoes and ran over to his wallet where his hungry keys were eating his lunch money.

If you add interesting details or humor, it often makes the information easier to remember.

State Dependent Memory:  We are more likely to recall information if we are in the same state we were in when we learned it.   For example, if we are hungry when we learn a list of scientific notations, we are more likely to remember them if we are hungry again.   The same is likely if we learned something when we were tired.  We would remember it better if we are tired.

On the BrainHQ Site – “Memories are made up of what you sense. Typically, when memory fails, it’s not because you forgot how to remember—it’s because your brain isn’t processing information very clearly or you weren't focused on the information.  BHQ exercises for memory can sharpen the brain’s ability to record this information so that you can create a clearer memory that’s easier to recall” (BHQ).   As with every category of exercises, the BHQ website gives you background about the subject (memory), an explanation about how each exercise works to improve that cognitive skill, and how scientific principles are applied to produce the benefit that we want.  Take a look at this Introduction to the Exercises that explains how many of the exercises overlap in the cognitive skills they strengthen and why it is important to recognize this fact. 

You can read more about the memory exercises and how they can help improve your memory, by clicking here: Exercises and scrolling down to the Memory Category of exercises (the pink icons).  Click on any exercise to read more about it and the benefits it provides, or click on the exercise of your choice below, for a version that includes a video demonstration of each exercise, or click on any of the underlines headings below. 

Hear, Hear            Memory Grid            Mind’s Eye           Rhythm Recall          Scene Crasher            Syllable Stacks            To-Do List Training

Optional Memory Activity: The BrainHQ program provides quite a memory workout. Memory improves when it is challenged and we accept that challenge by trying to focus, concentrate and remember. Here is another online activity that challenges your memory. Try it out and let us know how you do!   Remember the details 

Donnelly, L. (April 7, 2017). Scientists discover the ‘beautiful’ secret of how memories are made. The Telegraph. Retrieved from: http://www.telegraph.co.uk/science/2017/04/07/scientists-discover-beautiful-secretmemories-made/

Kitamura, T., Ogawa, S. K., Roy. D. S., Okuyama, T., Morrissey, M. D., . . . Tonegawa, S. (2017). Engrams and circuits crucial for systems consolidation of a memory.  Science, Vol. 356, Issue 6333, pp. 73-78.  doi: 10.1126/science.aam6808 

Maguire E. A., Gadian, D. G., Johnsrude, I. S., Good, C. D., Ashburner, J., . . . Frith, C. D. (2000). Navigation-related structural change in the hippocampi of taxi drivers.

Proceedings of the National Academy of Sciences of the United States of America, 97(8). 4398-4403.  doi: 10.1073/pnas.070039597.  Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC18253/

Mastin, L. (n.d.). Short-term (working) memory. The Human

Memory.  [Website].  Retrieved from: http://www.human-memory.net/types_short.html

Merzenich, M. (2013).  Soft-wired: How the new science of brain plasticity can change your life (2nd ed.).  San Francisco, CA: Parnassus Publishing, LLC.

Posit Science. (n.d.).  All about memory.  [Website]. Retrieved from: https://www.brainhq.com/brain-resources/all-about-memory

Posit Science. (n.d.a).  Session 15: Memory lapses handout. [Curriculum].  Not available on public website. 

San Diego State University (June 19 2017).  Mapping how words leap from brain to tongue: Neuroscientist explores the complex brain connections employed during word retrieval.”  ScienceDaily.  Retrieved from: www.sciencedaily.com/releases/2017/06/170619144827.htm

Trafton, A. (April 6, 2017). Neuroscientists identify brain circuit necessary for memory formation: New findings challenge standard model of memory consolidation.  MIT News.  Cambridge, MA: Massachusetts Institute of Technology.  Retrieved from: http://news.mit.edu/2017/neuroscientists-identify-brain-circuit-necessary-memoryformation-0406

Zimmerman, K. A. (2014a). Implicit memory: Definition and examples. Live Science. [Website]. Retrieved from: https://www.livescience.com/43353-implicit-memory.html

Zimmerman, K. A. (2014b). Semantic memory: Definition and examples. Live Science.

[Website]. Retrieved from: https://www.livescience.com/42920-semantic memory.html