Lecture 15 - Semantic Memory Flashcards
(21 cards)
What is semantic memory?
- Semantic memory is a sub-system of long-term declarative memory
- It refers to out general knowledge about the world, including facts, concepts, and meanings
How does semantic memory differ from episodic memory?
- Semantic memory: Knowledge of facts, concepts, and meanings without specific context
- Episodic memory: Memory of personal experience tied to time and place
- They are both forms of declarative (explicit) memory but serve different functions
What evidence supports the distinction between semantic and episodic memory?
- Amnesia: Typically impairs episodic memory more than semantic memory
- Semantic dementia: Impairs semantic memory while sometimes sparing episodic memory
Lesion evidence: - Episodic impairment: Medial temporal lobe damage (e.g., patient HM)
- Semantic impairment: Anterior frontal lobe damage
What did Kan, Alexander & Verfaellie (2009) find about semantic knowledge in memory?
- Participants learned grocery prices that were either congruent or incongruent with prior knowledge
- People with damage only to the medial temporal lobe (MTL) could benefit from semantic knowledge
- Those with MTL + other damage could not
- Conclusion: Damage outside the MTL may block access to semantic knowledge
What is the typicality effect in semantic memory?
It refers to the finding that people take less time to confirm that a category member belongs to a category when the item is typical (e.g., an apple is a typical fruit) compared to atypical (e.g., olive)
What did Loftus & Suppes (1972) show about category priming?
People respond faster when given the category first (e.g., think of a fruit that starts with r) rather than when asked for items starting with a certain letter (e.g., think of something starting with r)
What is the Collins and Quillian (1969) hierarchal network model of semantic memory?
- Concepts are arranged hierarchically
- Related concepts are stored close together
- Predicts faster response within the same level, slower across levels
- Problem: Empirical data did not always support this speed pattern
How does the Collins and Loftus (1975) spreading activation model improve on this?
- Concepts are represented as nodes connected by links
- Distance = semantic relatedness
- Activation spreads from one node to others
- More flexible than hierarchal models but questioned whether single-node representations are sufficient
How can semantic memory both help and hider memory recall?
- It provides schemas, scripts, and expectations, which help fill in gaps when episodic memory fails
- However, this can caue predictive memory distortions
What did Loftus and Palmer (1974) show about semantic memory’s influence on memory?
- Participants watched a car crash and were asked questions with different verbs (smashed vs hit)
- Those hearing smashed were more likely to recall seeing broken glass, showing suggestibility
Why don’t we make more memory errors if semnatic memory can mislead us?
The consistency of environments and our schemas often lead to accurate predictions
- Steyvers & Hemmer (2012): Using schemas (e.g., kitchen objects) usually leads to correct guesses
How do goals influence semantic memory activation?
- Barsalou (2009): Activation and spread of concepts are goal-dependent
- Which concepts activate depends on context and task demands
What did Linda-Domingo et al. (2019) find about smenatic retrieval?
When retrieving memories, semantic category information is accessed before perceptual details, showing top-down influence
What is the hub-and-spoke model of semantic memory (Lambon Ralph et al., 2017)?
- Combines a modality-invariant hub in the anterior temporal lobe (ATL) with modality-specific spokes (e.g., sound, vision, action)
- Semantic knowledge activates both amodal and modality-specifc systems
What neural evidence supports the hub-and-spoke model?
- Different lesion patterns = different semantic deficits
- Damage to the hub: Trouble with atypical category members or rejecting similar non-members
- Damage to spokes: Category-specific deficits
- Ishibashi et al. (2018): tDCS stimulations of hub improved general semantic access: stimulating motor spoke helped only with tool-use tasks
What is the role of semantic memory in decision-making and action?
- It provides rapid, structured knowledge used to guide actions and decisions
- Helps fill gaps in memory and improve recall accuracy in familiar contexts
Which brain region is typically damaged in episodic memory loss?
Medial temporal lobe
Which brain region is associated with semantic memory loss/
Anterior frontal lobe
What is the typicality effect?
Faster categorisaton of typical than atypical members
What activates first in memory retrieval, semantic, or perceptual info?
Semantic (Linde-Domingo et al., 2019)
What model includes a central hub and modality-specific spokes?
Hub-and-spoke model
