Download Chapter 7 Class Notes / Memory

GENERAL PSYCHOLOGY
Chapter 7
Human Memory
The Three Stage Memory Theory (Atkinson - Shiffron Theory)
The Three Stage Memory Theory divides memory processing into the levels of sensory memory, short-term
memory and long-term memory. Each of these levels is defined by its (1) function, (2) capacity and
(3) duration.
Sensory Memory
Function: The primary function of sensory memory is to hold information just long enough for it to be
selected for processing. Sensory memory also serves the adaptive function of helping us filter out large
amounts of unimportant information taken in by our sense organs. Therefore, SM performs its function
in a fraction of a second allowing us to selectively attend to important stimuli and disregard unimportant
stimuli.
Duration: Information can be held in SM only for a brief time (a fraction of a second). Iconic SM (visual
register) will hold an image of a stimulus for up to about 1/4 of a second. Echoic SM will hold a auditory
image for up to about 3-4 seconds. If the image flashed into our SM is not tagged as relevant, attended
to and moved into short-term memory, it will quickly be discarded.
Capacity: The capacity of SM is very limited. Depending on the amount of time exposure to the stimulus,
SM can only hold a few bits of information at a time. Even though it is limited in its capacity, SM is said
to hold an exact image of a stimulus. That is, the more cognitively active parts of our brains have not yet
had the chance to alter the information as a part of the process of perceiving it.
Short-term Memory
Function: STM has two primary functions: (1) to hold information just long enough for it to be used and
then discarded and (2) to hold information long enough to process it into long-term memory. Information
held in STM that is not used or processed into LTM will be discarded. Example: (function #1) holding a
telephone number long enough to dial it. Example: (function #2) holding a persons name while relating
it to the persons face and storing the name in LTM.
Duration: STM will only hold information for up to about 30 seconds if the information is not rehearsed.
That is, if the name of a person you've just met is heard, stored in STM briefly, but not processed into
LTM or rehearsed, it will likely be forgotten after about 30 seconds. Therefore it is important to note that
STM is rehearsal dependent. In order to hold information in STM for longer than 30 seconds, it must be
rehearsed. If something interrupts the rehearsal process, the information will likely be forgotten (if it has
not already made its way into LTM). As Benjamin Lahey notes, keeping several bits of information in
STM is like juggling several eggs. As long as you pay attention and are not distracted from your
juggling, you can continue the task. If you are distracted from the task, the results will not be good.
Capacity: STM can only hold about 7 bits (+/-2 bits) of information at a time. That is, the average is 7 (+/-2)
with a common range of 5 - 9 bits. A bit of information might be a number, letter, name or object. One
way we can organize and arrange information in order to store more in STM is through the process of
chunking. For example the number 9728815715 can become (972) 881-5715, which is much more
manageable for our STM.
Long-term Memory
Function: The obvious function of LTM is to hold information for an extended period of time that we need to
be able to function adaptively in our daily lives. With out LTM, we would not be able to remember
aspects of our identity, how to live safely or how to do any simple task of living. Three of the primary
function types of LTM include:
Semantic Memory -- the ability to recall meanings of concepts.
Procedural Memory -- the ability to recall the correct order of steps needed to successfully complete a
task.
Episodic Memory -- the ability to recall the sequence of happenings in a witnessed event.
Duration: According to most memory theorists, the memories we process into our LTMs are relatively
permanent. That is, most theorists believe once information is processed into LTM that it is, in some
form, always there. Some question this asking, "then why do I forget things?" Memory theorists reply
that the trouble is most often in the retrieval process. One of the two primary retrieval processes is
much easier to use as noted below. Retrieval processes include:
Recall -- retrieving information on the basis of a simple cue ("What is your home address?).
Recognition -- retrieving information by selecting from several choices provided ("I can't remember the
name of the breakfast cereal my kids asked me to buy so I'll go to the cereal aisle and look at all of
the boxes. Then I'll recognize the right one when I see it.").
Capacity: The capacity of LTM is believed to be unlimited. We can store an entire life-time of memories,
knowledge and experiences in a brain that, if anything, gets slightly smaller (not larger) as we move into
later adulthood. Getting information into LTM may be difficult if one of the following processes is not
used:
Experience & Meaning -- first and foremost, LTM stores information on the basis of meaning. Personally
relevant life experiences, especially emotionally powerful ones, are processed deeply into LTM.
Categorization -- LTM also stores information on the basis of categories, classes, and relationships
Novelty -- information that is distinctive, unusual or unique is also easily processed into LTM.
Repetition and Rehearsal -- repetition can be used to process information into LTM, especially if the
information is mundane, meaningless, not easily categorized (not the most effective method)
Levels of Processing Theory (Craik & Lockhart)
The Levels of Processing Theory, a competitor of the traditional 3-stage approach, is critical of that theory
on several points. The LOP Theory asserts that there is only one level of memory, not three. Remembering
and forgetting information is based on low deeply information is processed into memory. An example of
deep processing would be information like your name, address and phone number (info you need to function
in life). An example of shallow processing would be glancing at the name tag of a sales clerk and then later
being asked to recall it. Since it was not processed deeply, you probably can't recall the name, but might be
able to recognize it from a list later. LOP theorists reject the idea of three separately functioning areas of
memory in the traditional theory.