Situation Models and Embodied Language Processes Franz Schmalhofer University of Osnabrück / Germany 1) Memory and Situation Models 2) Computational Modeling of Inferences 3) What Memory and Language are for 4) Neural Correlates 5) Integration of Behavioral Experiments and Neural Correlates (ERP; fMRI) by Formal Models
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Situation Models and Embodied Language Processes
Franz Schmalhofer
University of Osnabrück / Germany
1) Memory and Situation Models
2) Computational Modeling of Inferences
3) What Memory and Language are for
4) Neural Correlates
5) Integration of Behavioral Experiments and Neural Correlates (ERP; fMRI) by Formal Models
Cognition and Knowledge
• Traditional:
– Cognition = Computation
– Representation by propositions
– Propositions are abstract relations
• Embodiment of Meaning
– Cognition is serving perception and actions
– Representation = Patterns of possible bodily interactions with the world (lawfully related to the world)
– What an object, event, sentence means for you, is what you can do with the object, event, sentence.
Embodiment of Memory (Glenberg, 1997)
• Projectable properties: information available through the senses
• Non-projectable properties: information available through other sources (e.g. memory)
• Conceptualization: Combination (mesh) of projectable and non-projectable properties
Primary function of memory is to mesh the embodied conceptualizations of projectable properties of the environment with embodied experiences that provide non-projectable properties
Embodiment of Memory
• Evidence for embodiment...• ...and affect:
– Forced frowning or smiling influences affective judgments (Berkowitz & Trocolli 1990, Berkowitz et. al 1993)
• ...and imagery:– Actually rotating facilitates orientation opposed to imagining
– fMRI: blood oxygenation level dependent effect or BOLD effect
Brain functions (1810-1819)
• Do parts of the brain working independently enable the mind? (componential hypothesis)
• Franz Joseph Gall and J. G. Spurzheim– 35 specific brain functions– Language, color perception,
hope, self-esteem– With practice, areas grow,
causing a bump in the overlying skull
– Anatomical personology– phrenology
• Does the whole brain work in concert?(wholistic hypothesis)
• Pierre Flourens (1794-1867)– All sensations, all perceptions
and all volitions occupy the same seat in these cerebral organs.
– The faculty of sensation, percept and volition is then esssentially one faculty.
– Empirical evidence: no matter where he leasoned a bird brain, the bird recovered
Language Areas
• Broca • Wernicke
Neuroanatomist Korbinian Brodman (1909)
• Analyzed cellular organization of the cortex
• Tissue stains to visualize different brain regions
• To a large extent cytoarchitecturally described brain areas do indeed represent functionally distinct brain regions
Componential or wholistic? Again the question
• Camillo Golgi – Developed stain that
impregnated individual neurons
– Believed the whole brain to be a continuous mass of tissue that shares a common cytoplasm
• Cajal– Used Golgi stains
– Identified the unitary nature of neurons
– Transmittion of information by electricity
How does the nervous system work (20-th century)
• Understand how single neurons behave and interact
• Knowing all the elements, can we figure out the system?
• Billions of neurons
• Brain-damaged humans show lack of typical symptoms
• Impossible to localize „higher cognitive functions“
Jackson: Lesion might well affect other structures in the brain because the lesion might have damaged neurons connected to other regions; diaschisis: damage of one part can create problems for another.
Gestaltist view: The whole is different from the sum of its parts
Summary
• Localists– Wrong, in that they tried to map behaviors and perceptions into single
locations in the cortex
– Any behavior is produced by many areas
– Complex functions
• Globalists– A function can be achieved in numerous different ways (in this sense
the globalists were right)
• But – simple processes that are recruited to exercise an ability are localized
Event-Related Brain Potentials
What are event-related brain potentials (ERPs)
• Like EEG, but related to an event (a task, e.g. making a decision, reading a word, etc.)
• The ERP (a few µV is small in relation to the EEG (about 50µV)
• The international 10-20 system (Jasper 1958) allows for between-laboratory and between-experiment comparisons
EEG profiles obtained during various states of consciousness
After Penfield and Jasper (1954)
How ERPs are obtained from EEG-data
Schematic representation of ERP-Procedure
ERP-components
ERP-Components
• Usually labeled by polarity and latency, P300, P3 (ordinal latency of the component)
• Scalp locations, e.g. frontal P300• Psychological or experimental conditions
• Distant manifestations of activations of populations of neurons (recorded on surface of skull)
• Requirements– Neurons must act synchronously– Electric fields must be oriented so that they cumulate– Therefore only a subset of neural activity is visible– Open field organizations (dentritic trees are ordered), neurons
are organized in layers, most of cortex, parts of thalamus, cerebellum and others
• Sensory components– The early negatives (ERPs and locus of selective attention)
– The middle latency cognitive components (mismatch negativity of MMN)
– N200s (or N2)
• The late cognitive ERPs: – P300, elicited by deviant stimuli
– The “frontal” P3, elicited by novel stimuli, novelty P3 (no memory template is available
Some ERP-findings (continued)
• ERP effects associated with subsequent memory– Distinctive word (van Restoff, character change, large P300s; recalled
ones show larger P300s as compared to not recalled ones.– Same-different task (Sanquist et al., 1980) larger amplitude P300s were
better recognized in subsequent recognition test.– Two-process model of recognition (large P300 when explicit recollection
as opposed to “just know”
• N 400 (language-related)– More prolonged over the right rather than the left hemisphere– N400 may be generated by the parahippocampal anterior fusiform gyrus– A distinctively semantic process– Inversely related to the subject’s expectancy (cloze probability)– Semantically related to sentence completion produce smaller N 400. “The