Memories come in many different forms. There is much that researchers do not understand about human memory and how it works.
This article explores the types of memory and what a person can do to improve their recall.
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There are many theories about the types of memory within the human brain. Most scientists believe there are at least four general types of memory:
- working memory
- sensory memory
- short-term memory
- long-term memory
Some researchers suggest these are not distinct types of memory, but rather stages of memory.
In this view, memory begins in sensory memory, transitions to short-term memory, and then may move to long-term memory.
A memory a person uses only for a brief time, such as a word they use at the beginning of a sentence, is a part of working memory and may never move to another part of memory.
Some brain scientists divide these types of memory into more specific categories.
Sensory memory holds sensory information for very brief periods of time, usually 1 second or less. The processing of memories and other information begins in this type of memory.
If a person pays attention to sensory input, then the information may move into short-term and then long-term memory.
Some examples of sensory memory include:
- registering the sounds a person encounters on a walk
- briefly acknowledging something in a person’s field of vision
Sensory memory helps a person piece together a sense of the world based on recent sights, sounds, and other sensory experiences.
When a specific sensory experience becomes relevant, such as the smell of something in the kitchen, it may move to other types of memory.
Otherwise, sensory memories are very short-term, and a person quickly forgets them.
For example, a person will not recall all the specific sounds they heard in the last 30 seconds, 30 minutes, or 30 days unless there is some reason to remember them.
Short-term memory allows a person to recall a limited string of information for a short period.
These memories disappear quickly, after about 30 seconds.
Short-term memory is not just memory that does not last long. Instead, it is a type of short-lived storage that can only hold a few pieces of information.
Some examples of short-term memory include:
- remembering a string of 5–7 words and repeating it back
- remembering a phone number while getting a pen to jot it down
Working memory is similar to short-term memory. However, unlike the latter, working memory is where a person manipulates information.
This helps them remember details of their current task. Some behaviors that use working memory include:
- solving a complex math problem where a person must remember several numbers
- baking something, which requires a person to recall the ingredients they already added
- participating in a debate, during which a person must remember the main arguments and the evidence each side uses
While researchers typically separate working and short-term memory into two different categories, research often finds a significant overlap between the two.
Long-term memory stores a wide range of memories and experiences.
Most memories that people recall, especially those older than about 30 seconds, are part of long-term memory.
Many researchers divide long-term memory into two subcategories: implicit and explicit.
Explicit long-term memory
Explicit memories are conscious memories of events, autobiographical facts, or things a person learns.
Some types of explicit long-term memory include the following.
Episodic memory
These are memories of events or autobiographical facts. Examples of episodic memory include remembering an election, events from childhood, and personal facts, such as if someone is married.
Semantic memory
Semantic memories are general knowledge about the world. A person may remember a fact or event that they did not experience because they learned or studied it.
For instance, knowing what the human heart looks like is an example of semantic memory. However, it would be an episodic memory if the person can remember dissecting a pig heart in school.
Implicit long-term memory
Implicit memories are memories that influence a person’s behavior. However, people do not consciously think about them.
Some types of this memory include the following.
Procedural memory
Procedural memory helps a person perform familiar tasks, such as walking or driving.
At first, they might have to learn to do these things and remember specific skills, but eventually, these tasks become an automatic part of procedural memory.
Priming
Priming occurs when experiences influence a person’s behavior.
For example, a smoker might crave a cigarette after a meal, or an experimenter might train a person to press a button in response to a photo.
Classical and operant conditioning both prime people or animals to perform specific behaviors in response to certain experiences.
Working, sensory, and short-term memory have smaller capacities. This is because these types of memories only last for a short period.
With short-term memory, there is usually a specific limit on how much information a person can retain — usually about seven items.
Some people could increase their short-term memory capacity with practice.
The brain is not a computer, and memories do not take up physical space. In theory, there is no specific limit on the capacity of long-term memory.
However, the quality of memories and their details may vary and change with time.
Memories may be unreliable
The brain does not record memories perfectly, so memories may change or disappear with time.
Numerous studies suggest that memories are not reliable, even when a person remembers something very clearly.
In one 2015 study, researchers were able in just a few hours to convince innocent people they had committed serious crimes, such as assault with a weapon, in their teenage years.
Can someone have a photographic memory?
Some people have unusually good memories. People with hyperthymesia, an extraordinarily rare condition, may remember all or most autobiographical memories.
Others may practice memory skills to become better at memorizing information or recalling strings of words or numbers.
There is no scientific evidence anyone has a so-called photographic memory. The brain is not a camera and cannot perfectly record information.
Some strategies for improving memory include:
- Developing mnemonic devices for remembering new information. For example, remembering all the names in a room could involve making up a rhyme or an association for each name.
- Doing brain teasers and challenging puzzles.
- Developing strong memory associations to help remember things. Talking about recent memories or journaling can help cultivate these associations.
- Doing cardiovascular exercise to promote brain health.
The memory is a complex system, not a single organ or process.
A person may improve their memory by adopting a healthful lifestyle and practicing strategies specifically designed to promote recall.
People concerned about their memory should see a doctor, as any unexplained changes could signal a range of medical conditions.
Also Called: Rapid cycle improvement, PDCA (plan-do-check-act)
What is PDSA?
Stage 1: Plan
Stage 2: Do
Stage 3: Study
Stage 4: Act
Examples
More information
PDSA, or Plan-Do-Study-Act, is an iterative, four-stage problem-solving model used for improving a process or carrying out change.
In applying PDSA, ask yourself three questions:
- What are we trying to accomplish?
- How will we know that a change is an improvement?
- What changes can we make that will result in an improvement?
A. Recruit team
Assemble a team that has knowledge of the problem or opportunity for improvement. Consider the strengths each team member brings—look for engaged, forward-thinking staff.
After recruiting team members, identify roles and responsibilities, set timelines, and establish a meeting schedule.
B. Draft an aim statement
Describe what you want to accomplish in an aim statement. Try to answer those three fundamental questions:
- What are we trying to accomplish?
- How will we know that a change is an improvement?
- What change can we make that will result in improvement?
C. Describe current context and process
brainstorm
Examine your current process. Start by asking the team these basic questions:
- What are we doing now?
- How do we do it?
- What are the major steps in the process?
- Who is involved?
- What do they do?
- What is done well?
- What could be done better?
You might have already answered the last two questions if you have performed a SWOT analysis.
Try a swim lane map
You may find it helpful to construct a swim lane map to visually describe your process.
Creating a process flow or at least depicting the current process can be very useful. If your team runs into road blocks, you might have found where the problem is occurring—or maybe the right person for identifying a missing step is not at the table.
Gather more detail
Once the general structure is completed, these can be some more helpful questions to ask:
- How long does the process currently take? Each step?
- Is there variation in the way the process is currently completed?
D. Describe the problem
Using the aim statement created in Step B, state your desired accomplishments, and use data and information to measure how your organization meets/does not meet those accomplishments.
For example: If your objective is to maximize your staff's quality of work life, you might find evidence by surveying employees on workplace stressors.
Write a problem statement
Write a problem statement to clearly summarize your team's consensus on the problem. You may find it helpful to prioritize problems, if your team has identified more than one, and/or include a justification of why you chose your problem(s).
E. Identify causes and alternatives
Analyze causes
For the problem in your problem statement, work to identify causes of the problem using tools such as control charts, fishbones, and work flow process maps (e.g., flowcharts, swim lane maps). The end of the cause analysis should summarize the cause analysis by describing and justifying the root causes.
Examine your process, and ask:
- Is this process efficient? What is the cost (including money, time, or other resources)?
- Are we doing the right steps in the right way?
- Does someone else do this same process in a different way?
Develop alternatives
Try to mitigate your root causes by completing the statement,
"If we do __________, then __________ will happen."
Choose an alternative (or a few alternatives) that you believe will best help you reach your objective and maximize your resources.
Develop an action plan, including necessary staff/resources and a timeline. Try to account for risks you might face as you implement your action plan.
Start to implement your action plan. Be sure to collect data as you go, to help you evaluate your plan in Stage 3: Study. Your team might find it helpful to use a check sheet, flowchart, swim lane map, or run chart to capture data/occurrences as they happen or over time.
Your team should also document problems, unexpected effects, and general observations.
Using the aim statement drafted in Stage 1: Plan, and data gathered during Stage 2: Do, determine:
- Did your plan result in an improvement? By how much/little?
- Was the action worth the investment?
- Do you see trends?
- Were there unintended side effects?
You can use a number of different tools to visually review and evaluate an improvement, like a Pareto chart, control chart, or run chart.
Reflect on plan and outcomes
- If your team determined the plan resulted in success, standardize the improvement and begin to use it regularly. After some time, return to Stage 1: Plan and re-examine the process to learn where it can be further improved.
- If your team believes a different approach would be more successful, return to Stage 1: Plan, and develop a new and different plan that might result in success.
The PDSA cycle is ongoing, and organizations become more efficient as they intuitively adopt PDSA into their planning.
Celebrate improvements and lessons learned
- Communicate accomplishments to internal and external customers
- Take steps to preserve your gains and sustain your accomplishments
- Make long-term plans for additional improvements
- Conduct iterative PDSA cycles when needed
The ABCs of PDCA and PDSA Flowchart (PDF)
Public Health Foundation
Embracing Quality in Local Public Health (PDF)
Michigan Local Public Health Accreditation Program
Baldrige Performance Excellence Program
National Institute of Standards and Technology, US Dept. of Commerce
Balanced Scorecard Institute
PDSA [Note: Video will autoplay]
Institute for Healthcare Improvement
Whiteboard: The PDSA Cycle (Part 1) [Note: Video will autoplay]
Whiteboard: The PDSA Cycle (Part 2) [Note: Video will autoplay]
Institute for Healthcare Improvement