Psychology2016

Memory 237

LONG-TERM MEMORY ORGANIZATION As stated before, LTM has to be fairly well
organized for retrieval to be so quick. Can you remember the name of your first-grade
teacher? If you can, how long did it take you to pull that name out of LTM and pull it
into STM? It probably took hardly any time at all.
Research suggests that long-term memory is organized in terms of related mean-
ings and concepts (Collins & Loftus, 1975; Collins & Quillian, 1969). In their original
study, Allan Collins and M. Ross Quillian (1969) had subjects respond “true” or “false” as
quickly as possible to sentences such as “a canary is a bird” and “a canary is an animal.”
Looking at Figure 6. 5 , it is apparent that information exists in a kind of network, with
nodes (focal points) of related information linked to each other in a kind of hierarchy.* To
verify the statement “a canary is a bird” requires moving to only one node, but “a canary
is an animal” would require moving through two nodes and should take longer. This
was exactly the result of the 1969 study, leading the researchers to develop the semantic
network model, which assumes that information is stored in the brain in a connected
fashion with concepts that are related to each other stored physically closer to each other
than concepts that are not highly related (Collins & Quillian, 1969).
The PDP model (Rumelhart et al., 1986) discussed earlier in this chapter can
be used to explain how rapidly the different points on the networks can be accessed.
Although the access of nodes within a particular category (for example, birds) may take
place in a serial fashion, explaining the different response times in the Collins and Quil-
lian (1969) study, access across the entire network may take place in a parallel fashion,
allowing several different concepts to be targeted at the same time (for example, one
might be able to think about birds, cats, and trees simultaneously).
Perhaps the best way to think of how information is organized in LTM is to think
about the Internet. A person might go to one Web site and from that site link to many other

semantic network model
model of memory organization that
assumes information is stored in the
brain in a connected fashion, with
concepts that are related stored phys-
ically closer to each other than con-
*hierarchy: a ranked and ordered list or series. cepts that are not highly related.

Figure 6.5 An Example of a Semantic Network
In the semantic network model of memory, concepts that are related in meaning are thought to be stored physically near each other in the
brain. In this example, canary and ostrich are stored near the concept node for “bird,” whereas shark and salmon are stored near “fish.”
But the fact that a canary is yellow is stored directly with that concept.

Canary Ostrich Shark

Can sing

Is yellow

Has long

thin legs

Is tall

Can't fly

Can bite

Is dangerous Salmon

Is pink

Is edible

Swims upstream to lay eggs

Bird

Animal

Has skin

Can move around

Eats

Breathes

Has wings

Can fly

Has feathers

Has fins

Can swim

Fish Has gills

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