Meaning in Mind and Brain Flashcards
Four types of semantics in Pulvermuller’s paper (essential reading)
Referential
Combinatorial
Emotional-affective
Abstract
Referential semantics
Establishes links between symbols and the objects/actions they refer to
Combinatorial semantics
Enables the learning of symbolic meaning from context
Emotional-affective semantics
Establishes links between signs and internal states of the body
Abstract semantics
Generalises over a range of instances of semantic meaning
The ‘standard view’ of the mechanism of meaning
- Amodal, symbolic semantic system
- Separate from action/perception systems
Grounding problem
A person just knowing the (syntactic) relationship between symbols cannot be said to know the (semantic) meaning of these symbols
Needs a link between sign, concept and referential information
Brought to light by Searle’s Chinese Room argument
Harnad’s hybrid model
Attempt to solve grounding problem:
1) Perceptions lead to iconic representations of objects
2) Shared features of many iconic representations of the same thing brings a grounded categorical representation
3) Further symbolic representations are built by combining grounded ones (zebra: horse with stripes)
Two problems with Harnad’s hybrid model
- Not biologically realistic
- Ignores other types of meaning apart from object reference
Types of neurocognitive models for meaning
Symbolic model
Distributed model
Hybrid model e.g. integrated cell assembly (CA) model
Integrated cell assembly (CA) model
CA = distributed circuit that ‘carries’ symbols in a network
Strengths:
- Biologically plausible(?)
- Solves grounding problem(?)
Sensorimotor grounding of meaning?
Concepts and meanings need to be grounded in motor action and/or sensory perception. At least for some symbol types, an ‘amodal semantic system’ is insufficient.
Neural reuse of APCs in accordance with Hebbian learning
Could explain how cortical circuits for concepts develop and why they have specific:
- localisation
- temporal dynamics
- function
Evidence for sensorimotor role in meaning
1) Explains otherwise puzzling (behavioural, neuroimaging, lesion) evidence for:
- Information sharing between e.g. motor, visual, auditory cortices
- Semantic (conceptual) processing reflected by actions and perceptions e.g. ACE
- SPP plus N400 paradigm
2) Biologically plausible theory given brain structure:
- APCs are distributed, long-range and multimodal, but not randomly so
- Sensorimotor and mirror neurons
3) Consistent with biologically-constrained simulation data and their ‘emergent topographies’:
- Specialised ‘semantic hubs’
- Category-specific semantic areas
4) Allows for many ways of learning
Action compatibility effect (ACE)
People respond faster to sentences if the meaning matches the direction of the response
e.g. towards/away from something
Grounding transfer
aka ‘Symbolic theft’
Word-word correlation learning (as opposed to word-world):
Previously learnt word + novel word form → new semantic circuit