Semantic Representations, Lecture 8 Flashcards
Do non-humans animals have language, and what types?
Yes, researched by Washoe, Koko and Kanzi.
Washoe learned around 200 manual signs (sign language)
Koko learned around 1,000 signs, and was able to combine in complex ways (sign language)
Kanzi learned around 200 symbol “lexigrams”
What did Searle take away from the Chinese Room Problem?
That syntax doesn’t suffice for semantics - you have to understand meanings of thought contents.
What is semantic memory?
Conceptual (general) knowledge of the world - meanings of words and objects, as well as factual knowledge
What are the neural bases of semantic memory?
Temporal lobes
What role does semantic memory have in human cognition?
Lies at the interface of language, memory and perception
What is the N400?
Component of time-locked EEG signals known as ERPs. It is a negative-going deflection that peaks around 400 milliseconds post stimulus onset.
How did Kutas & Hillyard use the N400 to measure semantics?
Ppts read sentences word-by-word. Two conditions: Semantically appropriate ending; Semantically inappropriate ending. ERPs were time-locked to the appearance of the last word.
What were the results/conclusions from the Kutas & Hillyard, 1980?
Ppts anticipated the last word of the sentence. Incorrect endings - mismatch between expectation and the actually presented word. Mismatch elicited a larger N400 component.
How did Parise and Csibra demonstrate that we can use the N400 to investigate the development of semantic representations?
Investigated 9 month old infants - detect the mismatch between an object appearing from behind an occlude and a preceding label. The label primes the object that should appear. Infants understood the meaning of some words.
What kind of N400 do semantically related words elicit?
A small N400 in comparison to semantically unrelated words
How was N400 modulated?
By the semantic connection between the expected and presented word.
What is a concept and what does it represent?
It unites things on the basis of similarity of characteristics. It represents classes of things, events or ideas.
When you activate a concept, what happens?
It will activate associated concepts
How are concepts organised?
In a network.
What are features?
Properties of or facts about a concept. Features are also linked together via a network
What do all models propose in terms of concepts and features?
That concepts are comprised of a constellation of constituent features
What are amodal representations?
Features are represented as abstract knowledge. They are not tied to sensory or motor information, and are independent of input or output modality.
Why was semantic memory traditionally assumed to be amodal?
It can be accessed from multiple kinds of sensory input
What is the Hierarchical Model?
Concepts are organised in a hierarchy. Features are associated with the concept at the appropriate levels.
What type of model is the hierarchical model and why?
Amodal, as concepts are represented as abstract knowledge.
Who proposed the Hierarchical Model?
Collins & Quinlan (1969)
What is the evidence from neuroscience for Hierarchical Model?
fMRI study of naming and categorisation (Rogers et al., 2006). Superordinate and subordinate information have different neural substrates.
What part of the brain does subordinate-level processing activate?
Anterior temporal pole
What part of the brain does superordinate-level processing activate?
Posterior temporal lobes
