Semantic Memory Flashcards
Semantic Memory
Organized knowledge about the meanings of words and the contents of the world
How is semantic memory different from episodic memory
You do not need to remember when and where you learned it (temporal and spatial context unnecessary)
Define the key features of Wittgenstein’s category membership
Family resemblance: members of a category can be related without sharing all properties
Centrality: some members are better examples of the category than others
Gradient: degrees of category membership
Compare the two theories for how semantic memory is organized
Prototype theory: extracted set of features that are highly probable for a category
Exemplar theory: all category members are stored in memory, categorizing a novel object by comparing its similarity to the memory representations of all previous exemplars from each relevant category
Limitations of prototype theory
Item may be closer to prototype A but belong in prototype B → a bat is not a bird but it is more closely associated with bird category
Prototype most closely represents central tendency
Prototypes differ with context: seagull at beach, lark in woods
Limitations of exemplar theory
Requires a lot more information stored, instead of one prototype representation, there’s a need for remembering all exemplars seen
Compare the options and ways that semantic memories can be stored in brain
Option #1: different brain areas represent different semantic categories
Foods vs vegetables vs animals all in different brain parts
Option #2: different brain areas represent different semantic features
Animate objects are represented by sensory features (stripes, spots), inanimate objects are represented by function (vase, jar, jug are used for storing)
Compare how semantic memories are related to each other
Taxonomically: two concepts can share many features (e.g., alive, has fur, lives in trees)
Thematically: two concepts can share similar event structures (e.g., both found at wine bars)
Compare the ways semantic memories can be stored and organized in brain
Semantic features are distributed across the brain
Anterior temporal lobes form a semantic hub that integrates taxonomic semantic features across the brain
Angular gyrus encodes thematic semantic relationships
What is semantic memory used for?
Similarity judgments - Your friend asks you to pick up peaches at the grocery store, but they are out of stock…
Semantic inference - You hear about a fruit called Yuzu, which your friend says is like a lemon and grapefruit combined…
Creative problem solving - You need to hold papers together, but you can’t find a paperclip…
Creative language - Describe the backyard scene in front of you: “The watering can is like a giraffe looking over the garden”
Standard Consolidation Theory
The theory that the hippocampus and related medial temporal lobe structures are required for storage and retrieval of recent episodic and semantic memories but not older ones.
Multiple Trace Theory
The theory that episodic (and possibly semantic) memories are encoded by an ensemble of hippocampal and cortical neurons and that both the hippocampus and cortex are normally involved in storing and retrieving even very old memories.
Each time that memory is retrieved, the retrieval itself becomes a new episodic memory. Thus, an old and often-recalled event can have multiple “memory traces” in the brain.
Individuals with hippocampal damage would effectively lose all their episodic memories
