Models of Memory
Different models are used to explain memory. No model accounts for all memory phenomena.
The general information processing modelcompares our mind to a computer. According
to this model, input is information. First input is encodedwhen our sensory receptors send
impulses that are registered by neurons in our brain, similar to getting electronic information
into our computer’s CPU (central processing unit) by typing. We must storeand retain the
information in our brain for some period of time, ranging from a moment to a lifetime,
similar to saving information into our computer’s hard drive. Finally, information must be
retrievedupon demand when it is needed, similar to opening up a document or applica-
tion from the hard drive. Donald Broadbent modeled human memory and thought
processes using a flow chart that shows competing information filtered out as it is received
by the senses and is analyzed in the stages of memory. According to his filter theory,
unimportant information is dropped and relevant information is encoded into the next
stage, as in a basic computer.Levels of Processing
According to Fergus Craik and Robert Lockhart’s levels of processing model,how long
and how well we remember information depends on how deeply we process the informa-
tion when it is encoded. With shallow processing,we use structural encoding of superfi-
cial sensory information that emphasizes the physical characteristics, such as lines and
curves, of the stimulus as it first comes in. We assign no relevance to shallow processed infor-
mation. For example, once traffic passes and no more traffic is coming, we cross the street.
We notice that vehicles pass, but don’t pay attention to whether cars, bikes, or trucks make
up the traffic and don’t remember any of them. Semantic encoding,associated with deep
processing, emphasizes the meaning of verbal input. Deep processingoccurs when we
attach meaning to information, and create associations between the new memory and exist-
ing memories (elaboration). Most of the information we remember over long periods is
semantically encoded. For example, if you noticed a new red sports car, just like the one
you dream about owning, zoom past you with the license plate, “FASTEST1,” and with
your English teacher in the driver’s seat, you would probably remember it. One of the best
ways to facilitate later recall is to relate the new information to ourselves (self-referent
encoding).Three-Stage Model
A more specific information processing model, the Atkinson–Shiffrin three-stage model of
memory,describes three different memory systems characterized by time frames: sensory
memory, short-term memory (STM), and long-term memory (LTM) (see Figure 11.1).
External events from our senses are held in our sensory memoryjust long enough to be
perceived. In sensory memory, visual or iconic memorythat completely represents a visual
stimulus lasts for less than a second, just long enough to ensure that we don’t see gaps between
frames in a motion picture. Auditory or echoic memorylasts for about 4 seconds, just long
enough for us to hear a flow of information. Most information in sensory memory is lost.
Our selective attention,focusing of awareness on a specific stimulus in sensory memory,
determines which very small fraction of information perceived in sensory memory is encoded
into short-term memory. Encoding can be processed automatically or require our effort.
Automatic processingis unconscious encoding of information about space, time, and
frequency that occurs without interfering with our thinking about other things. This is
an example of parallel processing,a natural mode of information processing that involves128 ❯ STEP 4. Review the Knowledge You Need to Score High