Memory and Your Brain
Click here for an overview of this topic mapped on Prezi
"Even the single most distinctive talent of human cognition, the ability to write and speak in a language, exists because of active remembering. Memory, it seems, makes us not only durable but also human."
John Medina, Brain Rules (2008)
What is memory?
Memory is usually described as the process by which the brain encodes, stores, and retrieves information.
Encoding is the process of transforming the information we receive from the outside world through our senses into the electrical and chemical signals that activate our brain cells.
Storing refers to the changes that happen in the brain to keep information over periods of time.
Retrieving is the process of locating information stored in the brain to make it available to us.
When we store information, we are creating a memory. What the information is, and how long we store it, determines what type of memory it is.
Different models or classification systems are used to help us understand different types of memory. Our model provides two major memory classifications - short-term memory and long-term memory.
Short Term Memory
Short-term memory is temporary. This information is not stored. It is kept in mind for a short time before it is transferred to long-term memory, or dismissed - i.e., lost to memory.
The term working memory is often used interchangeably with short-term memory. However, short-term memory refers more generally to temporarily holding information and determining if it will be transferred to long-term memory or dismissed. Working memory suggests a more specific and active idea of the brain keeping information - e.g., a name of phone number - "in mind" just long enough for immediate use, after which the information is lost to memory.
Long-term memory may be conscious/explicit, like remembering facts, concepts, events, etc.
Conscious memory may be autobiographical - i.e., about personal events and their contexts. Or they may be semantic - i.e., facts, information, concepts, meanings.
Other memories are unconscious/implicit, and do not require conscious thought, like riding a bike.
Unconscious memory may be procedural - i.e., automatic how-to knowledge. Or they may involve priming - i.e., association or recent experience may prime or prompt a memory.
Our level of knowledge or expertise and frequency of retrieving or using our memories and skills will affect the storage strength and retrieval strength of our memories.
The networks that are activated when we retrieve a memory or learn a skill include many of the same cells that are activated to form the memory or skill.
The harder we strive to retrieve a memory, the greater the impact on storage and retrieval strength.
Some memories are stronger and relatively easier to retrieve than weaker memories that may require prompting or reminding. Even stronger memories are not fixed or necessarily reliable.
Memories change as we merge them with other experiences and other memories. Also, networks change every time they are activated, and memories are altered everytime they are retrieved.
Types of memory
The degree of emotion connected to personal experiences and events affects whether or not they are stored, as well as how strongly we remember them. Usually, the stronger the emotion, the stronger the memory.
Conscious memory, also referred to as explicit or declarative memory, is a type of long-term memory.
It requires conscious thought - such as remembering the names of countries and capitals of South America, dates and events in world history, or personal and lived experiences.
Conscious memory may be autobiographical - i.e., about personal events and their contexts.
Autobiographical memory is also called episodic memory. It enables our recollection of personal experiences, events in our lives, and their contexts - e.g., celebrating a graduation, losing a job, etc.
Conscious memory may also be semantic memory - i.e., facts, information, concepts, meanings.
Unconscious memory, also referred to as implicit or nondeclarative memory, is a type of long-term memory. However, unlike explicit memory, it does not require conscious thought.
It allows us to perform learned skills and procedures by rote - i.e., without having to think about the steps or process involved.
Procedural memory is one type of implicit or nondeclarative memory, and a form of unconscious long-term memory.
Procedural memory enables us to perform learned everyday actions, without having to consciously think about the steps or processes involved.
Driving a car, using a computer, walking or jogging, using a fork or chopsticks, are actions that, once we have learned them, are enabled by our procedural memory.
The idea of "priming" relates to experience and the retrieval of implicit memory - i.e., experience as priming for implicit memory.
Repeating a procedure or experience often strengthens our neuronal pathways and results in speedier memory retrieval.
The more often we do a task, the more quickly and successfully we accomplish it. Fewer experiences result in slower memory retrieval. Age and cognitive conditions are also factors.