Semantic Long-Term Memory

Chapter 7 of Psych 270

What is semantic memory

Our permanent memory store of general world knowledge

What is Loftus & Palmer (1974) study

Showed people car accidents and asked:

-How fast were the cars going when they ____ each other?

Follow up question:
-Was there broken glass?

Depending on the word used, the answer changes (smashed: 30% yes, contacted: 10% yes)

What is the collins & quillian model

A network model of semantic memory

What is network

An interrelated set of concepts/body of knowledge

What is node

A point of location in the network representing a single concept

What is pathways

Labeled directional associations between concepts

What is spreading activation

The mental activity of accessing and retrieving information from the network
Takes passive concepts and activates them
Activation then spreads to related nodes

What are propositions

Express a relationship between two concepts (a robin has wings; an apple is a fruit)

How do pathways and propositions work together

Pathways connect two nodes together to form propositions

What are ISA pathways

They express category membership (e.g., a robin is a bird)

What are property pathways

They express properties that concepts possess (e.g., a robin has the property of wings)

What is intersection search

Two concepts can be activated, each with spreading activation to related nodes

What is semantic relatedness

The distance between two nodes in a network is determined by semantic relatedness
Concepts close in meaning/highly related are stored close together in memory
Unrelated concepts are stored far away

What are feature lists

Contain semantic features (simple, one element characteristics) of each concept stored in memory
More parsimonious

What are defining features

Features absolutely essential to the concept
Appear at the top of each feature list

What are characteristic features

Features that are common but not essential to the meaning of a concept
They appear at the bottom of each feature list

What is feature comparison

The major process of information retrieval in the feature list model
To answer, first access each feature list from memory
Second, compare each list for common features (feature overlap)

What are the stages in feature comparison

1. Comparison is fast and involves a global comparison of how much the features in each list overlap

2. Comparison is slow, occurring only when the lists have an intermediate amount of overlap

What are the problems with feature comparison

No objective way to define a feature as a defining or characteristic feature
Does not account for fuzzy boundaries
Limited feature lists

What is the sentence verification task

True or false: an x is a y?
E.g., true or false: a robin is a bird?
Response time is measured

What is Collins & Quillian (1969) key prediction

Two concepts that are closer in the network should take less time to verify than two that are farther apart

What is this graph

Collins & Quillian 1996 model

What was Collins & Quillian (1969) results

Good initial results, but the results of other research indicated problems with the idea

What is semantic relatedness

Concepts that are more highly interrelated are retrieved faster
Example: Name the 12 months of the year; now name them in alphabetical order

What are typicality effects

Some members of a category are more typical - more representative - than others
More typical members of a category are judged faster than are less typical ones
E.g., “a robin is a bird” is verified faster than is “a chicken is a bird”

What are the models of a typicality effect

The feature comparison model was built to explain this
Adding semantic relatedness to the network model allows it to explain

What was the incorrect notion from the original network model

That redundant information is not stored in semantic memory

What is schema

A mental framework or body of knowledge about some topic

What is scripts

Semantic knowledge that guides our understanding of ordered events

What is categorization

Combining entities (information, objects, people, events, etc.) into meaningful units, or categories, is critical for semantic memory
Help us quickly make sense of the world

What are the drawbacks of categorization

Stereotypes

What is the classic view of categorization

People create and use categories based on a system of rules
If something satisfies a set of rules, then it is a member of the category
Arranged according to scientific taxonomies

What is necessary features

If not present, not a member of category

What is sufficient features

Nothing more is needed to satisfy category membership

What is graded membership

Categories are loose and fuzzy
Some members of categories are “better” members than others

What are the characteristics of human categories

Graded membership, central tendency, and typicality

What is central tendency

There is some mental core or center to the category where the best members are found

What is typicality

The degree to which items are viewed as typical, central members of a category

What is the protype theory of categorization

Mental average
Compare new entities to established prototypes

What is prototypes

The central or core instance of a category

What are limitations of protype theory of categorization

No information about variability of members
No information about category size

What is exemplar theory

People mentally take into account each experience, instance or example, of the encounters they have had with members of that category

What is explanation-based categorization

Semantic categories are theories of the world we create to explain why things are the way they are

What are the different explanation-based categories

Ad Hoc categories and psychological essentialism

What is ad hoc categories

Categories created as needed, often spontaneously

What is psychological essentialism

Members of a category are treated as if they have the same underlying property or essence

What are the basic principles of semantic priming

The priming process takes time
The activation of primed concepts is smaller the more removed concepts are from the origin
The priming effect is reduced across time

What is prime

Stimulus presented first in the hopes of influencing some later process (processing a sentence related to a concept, processing a concept related to a sentence)

What is target

The stimulus that follows the prime

What is facilitation

Prime decreases processing time needed for the target

What is inhibition

Prime increases processing time needed for the target

What is retrieval induced forgetting

Remembering something causes us to forget something else. We could remember a piece of information that is incorrect but it causes us not to be able to remember what is actually correct

What was the marcel (1980) study

Lexical decision task
Presented primes followed by a “mask” (participants were unaware of the prime)
Prime facilitated lexical decisions even though Ps were unaware of the prime
The conclusion is that priming is an implicit process

What are context effects

Priming effects

What is Simpson (1981)

Ambiguity and priming (target word: duke; “The vampire was disguised as a handsome count”)

What is lexical memory

The mental lexicon or dictionary where word knowledge is stored (distinct from conceptual knowledge)

What is anomia

A deficit in word finding (PDP models (connectionists models) can be “lesioned” to mimic the effects of anomia)