Chapter 9 - Semantic Organization
• to retrieve related information from LTM, we must be able to organize our memory
• much of this organization is semantic - relies heavily on the meaning of the
• an effective way to organize information is to form hierarchies.
• two major classes of models are used:
• one model assumes that people compare the features of two categories to
determine their relationship
• one model assumes that the relation between two categories is stored directly in
memory in a semantic network - consists of concepts joined to other concepts by
links that specify the relation between them.
• spreading activation: the activation of a concept can lead to the activation of related
concepts as the activation spreads along the paths of the network.
Organization and Recall
• hierarchical organization can also inﬂuence performance by facilitating the recall of
• recall of hierarchical information
• one advantage of a well-organized memory is that it helps us retrieve information
in a systematic way.
• effects of organization are not limited to hierarchical organization
•Bower and colleagues presented people with associated words linked together
- people recalled many more words than when the same words were randomly
•semantic organization of the material improved recall, even though the
organization did not consist of a hierarchy.
• hierarchical organization can also help people recall numerical information from
STM as demonstrated by testing a single subject over a 1-year period
•subjects ability to recall groups of digits didnʼt generalize to letters.
• Building Semantic Networks
• one way to organize information is to construct a semantic network - show how
concepts are related to each other
• nodes: the format for presenting concepts in a semantic network
• links: the format to representing relations in a semantic network
• students who constructed semantic networks of a material did better than the
control group on short-answer and essay questions but did not do signiﬁcantly
better on the multiple-choice questions.
• constructing semantic networks is a good method for organizing knowledge, as
indicated by the resulting higher test scores on the open questions Veriﬁcation of Semantic Statements
• how effective organization, particularly hierarchical organization, increased the amount
of information that we can retrieve from the LTM
• hierarchical organization can also inﬂuence the time required to retrieve information
• feature-comparison model: a model proposing that items are categorized by
matching the itemʼs features to category features
• hierarchical network model: a model proposing that items are categorized by using
the hierarchical relations speciﬁed in a semantic network.
• The Hierarchical Network Model
• one advantage of this kind of network is that it provides an economical way to store
information because the information does not have to be repeated at each of the
• it is necessary to go to the appropriate level in the hierarchy before retrieving the
features stored at that level.
• made two primary assumptions:
•it takes time to move from one level in the hierarchy to another and
•that additional time is required if it is necessary to retrieve the features stored at
one of the levels
• the ﬁnding is consistent with the assumption that response time should increase if
it is necessary to retrieve the features stored at one of the levels in the hierarchy.
• Facilitation occurs when the retrieval of information is made easier because the
previous question required retrieval of similar information.
• does not account for the typicality effect - the fact that more typical members of
categories are easier to classify than less typical ones.
• model does not predict differences in response time
• The Feature Comparison Model
• model assumes that the meaning of words can be represented in memory by a list
of features and that classiﬁcations are made by comparing features rather than by
examining links in a network.
• deﬁning features: features that an entity must have to be a member of a category,
• characteristic features: are usually possessed by category members but are not
• has two stages:
•ﬁrst stage compares all the features of two concepts to determine how similar
one concept is to the other
•second stage is necessary when the degree of similarity is between the two
• model predicts that the more typical members of a category should be classiﬁed
more rapidly than the less typical members because evaluating the deﬁning
features during the second stage slows the classiﬁcation
• unlike the network model, this model provides an explanation of why some false
statements are evaluated more quickly than others (i.e. “A bat is a bird”)
• another advantage of this model is that it can account for the reversal of the
category-size effect •category-size effect: refers to the fact that people are usually able to classify a
member into a smaller category faster than int