Memory is the power of the brain to recall past experiences or information. In this faculty of the mind, information is encoded, stored, and retrieved. The purpose of our memory is to retain information that will influence our future actions. Without memory, we wouldn't be able to learn to speak, develop relationships, or possess personal identities. In the broadest sense, there are three types of memory. They are: sensory memory, short-term memory, and long-term memory.
Typically, when we think of the word "memory", we're referring to long term-memory, such as recalling our telephone number, what we did last Friday night, or who's quarterbacking for the New York Giants. But, our minds also possess sensory and short-term memory. Sensory memories are quick, lasting no more than seconds. Short-term memories are slightly less passing, but they still get dismissed after minutes. Long-term memories are those that stick with us for extended periods of time and usually require a bit of recall to be brought to the forefront of our minds. Not all long term memories are the same, however; their many types function in different ways.
Sensory memory is our shortest form of memory. It's no more than a flash. Sensory memory acts as a buffer for stimuli received through the five senses. These images are accurately retained, but only for a very brief moment in time.
Have you ever waved a sparkler in the air and seen a trail of light behind it? That's sensory memory: an image, a scent, a sound. Just as it sounds, sensory memory works with our senses to recall some quick flash of information. Here's another example:
- For Example - Riley walked into her kitchen and noticed the dead roses in her vase on the counter. She quickly recalled what they looked like when Luke first gave them to her. Then, she pulled them out, threw them in the garbage, and wondered what she might cook him for dinner tonight.
- For Example - Ellen took a drive to visit her childhood home. When she arrived, the song "Let's Hang On" by the Four Seasons came on the radio. It reminded her of those Sunday morning drives she used to take with her father.
There are three subcategories of sensory memory. They are:
- Iconic Memory - This refers to visual memories. This is how the brain remembers an image you have seen before. In the example above, Riley had an iconic memory of the flowers Luke gave her.
- Echoic Memory - Sometimes referred to as auditory sensory memory, this pertains to audio memories. Certain sounds will trigger memories of the past. In the example above, Ellen's flashback of her father was due to her echoic memory.
- Haptic Memory - This refers to memories involving the sense of touch. Here, the brain will flash memories of things you've touched before. If you didn't intellectually know a cactus would prick you if you touched it, the next time you saw a cactus, your haptic memory would shout, "Don't touch it!"
What about the other two senses? Even though we often hear that our sense of smell is our strongest link to the past, ironically, the above three subcategories are more extensively studied.
Have you ever smelled someone wearing your ex-girlfriend's perfume and had a flashback? Well, the sense of smell is pretty reliable because the part of your brain that processes smell sensations is very close to the part of your brain that processes memories.
Short-term memory, often interchanged with the name working memory, is temporary. It has a low capacity, as the information being processed will either be quickly dismissed, or entered into our long-term memory bank. It's sort of the precursor to long-term memory, which has many distinct facets with numerous functionalities.
- For Example - Lilly parked in the garage on Main Street. In order to pay for parking, she had to remember her parking space as she walked over to put money in the meter. Once she got the ticket, she placed it on her windshield and walked across the street to meet her friends for dinner. If you'd asked her what her parking space number was halfway through dessert, she might not be able to tell you.
Long-term memory is the brain's system for storing, managing, and recalling information. It is very complex with numerous different functionalities. As sensory memories only flicker for mere seconds and short-term memories last only a minute or two, long-term memories include anything from an event that occurred five minutes ago, to something that occurred twenty years ago.
There are many different forms of long-term memories. Sometimes they're conscious, requiring us to actively think in order to recall a piece of information. Other times they're unconscious, simply appearing without an active attempt at recollection (i.e. remembering how to drive from one city to another, even though you haven't taken that journey in nearly a decade). Let's take a look at some of the most prevalent forms of long-term memory.
- Explicit Memory - Sometimes referred to as conscious memory, this is the intentional recall of information.
- For Example - Every time Katie fills out a college application, she must consciously recall her full address, telephone number, and social security number.
- Declarative Memory - A variant of explicit memory, this involves the retention and recall of important facts, such as dates, events, and information.
- For Example - Every summer, August rolls around and Katie knows it's time to drive downtown and buy her best friend, Sara, a birthday card. August 30th is her birthday and Sara loves a good celebration.
- Episodic Memory - A form of declarative memory, this includes an ability to remember firsthand experiences from your life.
- For Example - Every time Mom calls to check in on Katie, she asks her what she did over the weekend. Katie must think back and recall the frisbee tournament she competed in on Saturday and the church meeting she attended on Sunday in order to tell her mother about them.
- Semantic Memory - Also a form of declarative memory, this refers to the memory's storage of vocabulary, key facts, names, and general knowledge.
- For Example - Katie's Mom loves the NY Giants, but she can never remember the quarterback's name. Julie constantly has to remind her that his name is Eli Manning.
- Implicit Memory - Sometimes referred to as unconscious memory, this includes the retention of information from a moment in time that can't specifically be recalled. You know how some things just "ring a bell"?
- For Example - Sasha's parents took her on a family vacation to the Jersey Shore when she was eight years old. Much later, during Spring Break in college, Sasha returned to the Jersey Shore with her sorority sisters and remembered exactly how to get to the boardwalk.
- Procedural Memory - A form of implicit memory, this is the ability to recall how to manually do things, from riding a bike, to driving a car.
- For Example - Sasha used to get in her car and run through a series of safety checks before driving. Are her mirrors properly positioned? Is her seat belt fashioned? Now, she just gets in and goes, without even thinking about all those safety checks she routinely conducts.
It's All in the Mind
Isn't the mind a fabulous study? It serves so many functions. It works as a receptionist in the form of sensory memory, admitting flashes into the mind. It also acts as judge and jury, deciding which facts will enter and exit quickly through the short-term memory bank, or advance into the long-term memory bank. It stores information for us to reach in and grab, whether we intentionally put it there, or don't even realize it's sitting there. The next time something "rings a bell" for you, give your mind a little pat on the back. It's giving you a nudge, as if to say, "Here, I think you might need this."