NB: You are responsible for reading the new textbook chapters accessible from the course web page.
Challenges: brains, emotions, consciousness, bodies, physical world, dynamic systems, social world, dynamic systems.
How to react?
What is a mental state, e.g. thinking of spring?
1. Dualism: mental state = non-material state of spiritual mind. E.g. Descartes, Eccles, religious views.
2. Idealism: everything is mental. Pan-psychism: everything is conscious, at least to a degree.
3. Identity theory: mental state = brain state. E.g. Smart 1950s.
4. Functionalism: mental state = functional state of an information processing system. There is an underlying physical state (functionalism is a kind of materialism) but the physical state places no constraints on mental states.
Argument from multiple instantiation: thinking could proceed just as well in different kinds of computers and in extraterrestrial brains, as in our. So the actual physical instantiation (hardware) is much less important than the software program. Putnam, Fodor, Johnson-Laird.
5. Eliminative materialism: do not try to equate mental states with anything, since our theory of mental states is just part of folk psychology which is largely false. Instead, replace talk of mental states with theories drawn from human neuroscience. Reject functionalism because it is crucial that thinking is based in human brains. Paul and Pat Churchland.
6. Integrative (methodological) materialism: folk psychology is a rough but not worthless approximation. Our views of mental states can change as better computational and neuropsychological theories are developed. In principle, different kinds of hardware could run different kinds of software, but in practice the physical instantiation matters a lot. Need to study the brain, as well as different kinds of computers, and Martians too if they come along.
7. Mysterian materialism: mental states are physical states, but are far too weird and complicated to be explained scientifically.
1. Dissection: discover the structure of the brain.
3. Electroencephalography (EEG)
4. Psychological experiments on people with brain damage, e.g. HM
1. CAT: Computerized axial tomography
2. PET : Positron emission tomography
3. MRI: Magnetic resonance imaging
4. fMRI: Functional magnetic resonance imaging
5. MEG: Magnetoencephalography
Head is inserted into a giant circular magnet
The magnet realigns atoms and protons
Machine sends a radio pulse that causes atoms to release energy
A computer detects energy release and produces an image
Functional MRI measures brain function by measuring changes in blood volume
Possible to map functions down to a few millimeters
Makes strong assumptions about relation between brain activity and blood flow
Numerous calculations required
Low temporal resolution because of sluggish metabolic response
A spike train is a chain of pulses (action potentials) emitted by a single
neuron. A spike usually lasts 1-2 ms. A spike train can be characterized by
a set of times, t1 ... tn, at which the neuron spikes, or by a series of ones
and zeros, where 1 means that the neuron spikes at a particular time and 0 means
that it is not spiking.
Whether a neuron N spikes at time t is a function of:
• the magnitude of the input to N, i.e. the electrical signals that N
is receiving from other neurons
• the firing threshold, which is the minimal amount of input needed to
fire
• refractoriness: after a neuron has fired, it takes a while before it
can spike again.
A background signal (e.g. from the brain stem) may provide a phase pattern that
allows different neurons to become synchronized or correlated with each other.
The brain is organized into regions. E.g. the GAGE model of Wagar and Thagard organizes neurons into groups representing cortex, hippocampus, amygdala, and nucleus accumbens. Neurons are not connected to every other neuron.
1. Empiricism: the mind is a blank slate, and everything is learned from experience.
2. Nativism: many concepts and rules are innate, e.g. universal grammar.
Evolutionary psychology: the brain has many innate modules derived from natural selection.
3. Neural constructivism: the brain has evolved, not to have innate specialized circuits, but to be able to acquire flexible representations through interactions with complex physical and social environments.
Molecules matter to mental computation:
- happy, sad, anger, fear, disgust. Maybe surprise.
How do these feel different? Are they confusable?
E.g. anger increases heart rate. Fear and sad increase skin temp.
Note also blood pressure, neural activity.
Oatley: emotions are tied in with goals.
Marvin Minsky: The Emotion Machine.
Analogical understanding using emotions.
Put yourself in another's shoes and have similar experiences. E.g. Olympics: skaters fall.
Question: what are the limits of empathy? Can you know what it is like to be a bat? What it is like to be of the opposite sex? What it is like to be a Maori?
Better question: what makes it hard to understand what it is like to be a member of the opposite sex?
Key ingredients in mapping:
situation + goals --> emotions (cf. Oatley)
Empathy as analogical mapping:
| Source (me) | Target (you) |
| my situation | your situation |
| my goals | your goals |
| situation + goals -> emotion | situation + goals -> emotion? |
| my emotion | your emotion? |
As in all analogies, my empathic understanding of you is based on
How far can the computational/representational understanding of mind (CRUM) go in helping us to understand emotions? Can it be tied in with the phenomenological and the physiological? We need an integrated theory of emotions that ties all of these together. Then emotions extend and supplement CRUM, but do not require its abandonment.
1. Elements have positive or negative valences.
2. Elements can have positive or negative emotional connections to other elements.
3. The valence of an element is determined by the valences and acceptability of all the elements to which it is connected.
Connectionist implementation: Units have valences as well as activations. Parallel constraint satisfaction operates on emotion as well as belief.
Other emotion articles by Thagard.
Computational Epistemology Laboratory.
This page updated Nov. 8, 2004.