Memory, an Introduction.
Human
memory, like memory in a computer, allows us to store information for later
use. In order to do this, however, both the computer and we need to master
three processes involved in memory. The first is called encoding;
the process we use to transform information so that it can be stored. For a
computer this means transferring data into 1’s and 0’s. For us, it means
transforming the data into a meaningful form such as an association with an
existing memory, an image, or a sound.
Next
is the actual storage,
which simply means holding onto the information (the process of saving
information in long term memory). For this to take place, the computer must
physically write the 1’ and 0’s onto the hard drive. It is very similar for us
because it means that a physiological change must occur for the memory to be
stored.
The
final process is called retrieval, which is bringing the memory out of storage and
reversing the process of encoding (the process of bringing material out of long
term memory and into consciousness). In other words; return the information to
a form similar to what we stored.
The
major difference between humans and computers in terms of memory has to do with
how the information is stored. For the most part, computers have only two
types; permanent storage and permanent deletion. Humans, on the other hand are
more complex in that we have three distinct memory storage capabilities (not
including permanent deletion). The first is Sensory memory,
referring to the information we receive through the senses. This memory is very
brief lasting only as much as a few seconds.
Short Term Memory (STM) takes over when the information in our sensory
memory is transferred to our consciousness or our awareness (Engle, Cantor,
& Carullo, 1993; Laming, 1992). This is the information that is
currently active such as reading this page, talking to a friend, or writing a
paper. Short term memory can definitely last longer than sensory memory (up to
30 seconds or so), but it still has a very limited capacity. According to
research, we can remember approximately 5 to 9 (7 +/- 2) bits of information in
our short term memory at any given time (Miller, 1956)
If
STM lasts only up to 30 seconds, how do we ever get any work done?
Wouldn't we start to lose focus or concentrate about twice every minute?
This argument prompted researchers to look at a second phase of STM that is now
referred to as Working Memory. Working Memory is the process that takes
place when we continually focus on material for longer than STM alone will
allow (Baddeley, 1992).
What
happens when our short term memory is full and another bit of information
enters? Displacement
means that the new information will push out part of the old information. We
can further sharpen our short term memory skills, however, by mastering
chunking and using rehearsal (which allows us to visualize, hear, say, or even
see the information repeatedly and through different senses).
Finally,
there is long
term memory (LTM), which is most similar to the permanent storage of a
computer. Unlike the other two types, LTM is relatively permanent and
practically unlimited in terms of its storage capacity. It’s been argued that
we have enough space in our LTM to memorize every phone number in the U.S. and
still function normally in terms of remembering what we do now. Obviously we
don’t use even a fraction of this storage space.
There
are several subcategories of LTM. First, memories for facts, life events, and
information about our environment are stored in declarative memory.
This includes semantic
memory, factual knowledge like the meaning of words, concepts, and our
ability to do math (Lesch & Pollatsek, 1993, Rohrer et al., 1995) and episodic memory,
memories for events and situations (Goldringer, 1996; Kliegel &
Lindberger, 1993).
The
second subcategory is often not thought of as memory because it refers to
internal, rather than external information. When you brush your teeth, write
your name, or scratch your eye, you do this with ease because you previously
stored these movements and can recall them with ease. This is referred to as nondeclarative
(or implicit) memory. These are memories we have stored due to extensive
practice, conditioning, or habits.
Why
We Remember What We Remember
Short
Term Memory.
There are typically six reasons why information is stored in our short term
memory.
1.
primacy effect - information that occurs first is
typically remembered better than information occurring later. When given
a list of words or numbers, the first word or number is usually remembered due
to rehearsing this more than other information.
2.
recency effect - often the last bit of information
is remembered better because not as much time has past; time which results in
forgetting.
3.
distinctiveness
- if something
stands out from information around it, it is often remembered better. Any
distinctive information is easier to remember than that which is similar,
usual, or mundane.
4.
frequency
effect -
rehearsal, as stated in the first example, results in better memory.
Remember trying to memorize a formula for your math class. The more you
went over it, the better you knew it.
5.
associations
- when we
associate or attach information to other information it becomes easier to
remember. Many of us use this strategy in our professions and everyday
life in the form of acronyms.
6.
reconstruction
- sometimes we
actually fill in the blanks in our memory. In other words, when trying to
get a complete picture in our minds, we will make up the missing parts, often
without any realization that this is occurring.
Long
Term Memory.
Information that passes from our short term to our long term memory is
typically that which has some significance attached to it. Imagine how
difficult it would be to forget the experience of the day you graduated, or the
experience of your first kiss. Now think about how easy it is to forget
information that has no significance; the colour of the car you parked next to
at the store or what shirt you wore last Thursday. When we process
information, we attach significance to it and information deemed important is
transferred to our long term memory.
There are other reasons information
is transferred. As we all know, sometimes our brains seem full of
insignificant facts. Repetition plays a role in this, as we tend to
remember things more the more they are rehearsed. Other times,
information is transferred because it is somehow attached to something significant.
You may remember that it was a warm day when you bought your first car.
The temperature really plays no important role, but is attached to the memory
of buying your first car.
Forgetting
You
can’t talk about remembering without mentioning its counterpart. It seems that
as much as we do remember, we forget even more. Forgetting isn’t really all
that bad, and is in actuality, a pretty natural phenomenon. Imagine if you
remembered every minute detail of every minute or every hour, of every day during
your entire life, no matter how good, bad, or insignificant. Now imagine trying
to sift through it all for the important stuff like where you left your keys.
There
are many reasons we forget things and often these reasons overlap. Like in the
example above, some information never makes it to LTM. Other times, the
information gets there, but is lost before it can attach itself to our LTM.
Other reasons include decay, which means that information that is not used for
an extended period of time decays or fades away over time. It is possible that
we are physiologically pre-programmed to eventually erase data that no longer
appears pertinent to us.
Failing to remember something
doesn’t mean the information is gone forever though. Sometimes the information
is there but for various reasons we can’t access it. This could be caused by
distractions going on around us or possibly due to an error of association
(e.g., believing something about the data which is not correct causing you to
attempt to retrieve information that is not there). There is also the
phenomenon of repression, which means that we purposefully (albeit
subconsciously) push a memory out of reach because we do not want to remember
the associated feelings. This is often sited in cases where adults ‘forget’
incidences of sexual abuse when they were children. And finally, amnesia, which
can be psychological or physiological in origin.
SOURCE: Memory http://allpsych.com/psychology101/memory.html