CONSCIOUSNESS
Phil/Psych 256
Chris Eliasmith
The ‘C’ Word
One main difficulty with consciousness is defining what we are talking
about:
Do we mean awareness (e.g., awake vs. asleep)?
Qualia (what-it-is-like)?
Noticeability (i.e. conscious as opposed to sub-conscious)?
Introspection (reporting on your internal states)?
Self-awareness (known who/what you are; self vs. other)?
These various meanings make sweeping claims about consciousness
difficult to verify or adjudicate.
A Definition
Main Entry: con·scious·ness (noun)
– Date: 1632
– 1 a : the quality or state of being aware especially of something
within oneself b : the state or fact of being conscious of an
external object, state, or fact c : AWARENESS ; especially : concern
for some social or political cause
– 2 : the state of being characterized by sensation, emotion, volition,
and thought : MIND
– 3 : the totality of conscious states of an individual
– 4 : the normal state of conscious life <regained consciousness>
– 5 : the upper level of mental life of which the person is aware as
contrasted with unconscious processes
That explains the confusion 
Consciousness and Science
An example (Sleep)
Experiments regarding the patterns of EEG changes during sleep
and waking have shown that specific kinds of wave activity can be
associated with certain kinds of unconscious (i.e., sleeping) states.
There are different patterns for deep sleep vs. REM sleep, so
different degrees (or types) of unconsciousness are apparent.
The neurobiology of sleep literature is huge, but there are many
unresolved issues, and the mechanisms of sleep have not been
pinned down.
One thing is clear in this case, is that understanding consciousness
in this sense is closely related to understanding how the brain
works.
There is little question that learning about the brain can teach us
something about consciousness.
But it's not clear whether or not the NCC is all there is to
consciousness
Consciousness Challenge
In philosophy, the challenge to cog sci is usually framed w.r.t qualia
'Qualia' is a name for the 'what it is like' of sensory experience, e.g.
what it's like to see red, or a square.
The first person, subjective experience of sensory states.
These sorts of phenomena are essentially ignored by past CRUM
approaches
The sleep example shows that the problem is more general
Consciousness Challenge
Thagard suggests we can't deny existence of qualia as we can deny
the existence of caloric because these are the experiences we all
know we have.
However, many have denied qualia (e.g. Dennett) – but not the
phenomena, just their classification as a kind of 'thing'
We don't have to deny experiences to deny that they should be
unified in a theoretical framework (see, e.g. heat, which is
identical to at least 4 very different processes).
Thagard is right, however, if we take him to simply mean that we
can't deny that there are first-person experiences.
Consciousness Challenge (cont.)
Just as for emotion Thagard seems to suggest that we might have
to supplement CRUM.
We need to expand CRUM because the contents of conscious
representations might be different and suggest new
computations.
We need to supplement CRUM because biological
considerations will introduce novel insights that are
incompatible with CRUM
Again, only expansion seems persuasive for the same reasons
as in the emotion case.
Crick and Koch
Crick and Koch break the problem of qualia into subproblems that
include:
1. What is consciousness for?
2. Why are some aspects of subjective experience impossible to
convey to others?
They answer these questions by claiming that:
1. (Visual) consciousness is for producing the best current
interpretation of the visual scene to guide voluntary action
2. Representations are constantly recoded, and recoding from visual
to motor representations (for speech) results in representations
that are related (but not identical)
They also think that there are two problems they can't yet answer:
3. How do we experience anything at all? and
4. What leads to a particular conscious experience?
consciousness
Social importance
Relative position
Sights
Sounds
consciousness
Broca’s area
recoding
Vision
monkey
Neural Correlate of Consciousness
NCC:
Make the problem of consciousness scientifically addressable (NCC).
Want to know which neurons are correlated to conscious experience,
why they are correlated and others are not, and what kinds of special
properties they have. Answering these scientific questions is sufficient.
They seem to assume only that some extensions of CRUM will have to
be made.
Problems with NCC:
Philosophers have often argued that finding correlations between brain
states and phenomena isn't enough for explaining consciousness.
Just because there is a correlation doesn't mean you have said what the
relation between brain states and consciousness is.
Furthermore, they have argued that because consciousness is subjective
and science is objective, science necessarily can't explain consciousness
(e.g. Nagel and Chalmers). This leads to a kind of dualism.
Neural Correlate of Consciousness
Responses to problems:
Like 'heat', 'consciousness' is supposed to be identical to some (perhaps
independent) physical states.
Just as we don't think of heat as being caused by the motion of particles, we
shouldn't think of consciousness as being caused by brain states
Ockham's razor says we should prefer the simpler theory, i.e. an identity
The subjective/objective distinction is simply two ways of accessing the same
phenomena. This is sometimes called a ‘dual-access’ theory (e.g., Schlick).
NCC Experiments
C&K describe the kinds of experiments they think are relevant to
understanding consciousness.
Blindsight (see what it's like on the web):
When large portions of V1, primary visual cortex, are destroyed,
patients report complete blindness; i.e. they are not visually
conscious.
However, on forced choice tasks (where they must answer yes or
no, left or right, etc.) they perform far better than chance for
locating objects.
When objects are moving, they do quite well.
If the objects move fast enough, they occasionally report vague
visual experiences.
C&K argue that another visual pathway (through the superior
colliculus and pulvinar) is sending small amounts of visual
information to the visual cortex, and that this can eventually (if
strong enough a stimulation) elicit partial conscious experiences.
Blindsight
NCC Experiments
Bistable percepts:
This takes advantage of binocular rivalry in which the items shown
to the two eyes are completely different (e.g. a face and a
starburst)
First one then the other percept is 'noticed' (seems to be an
entirely involuntary 'switching' of percepts between the two stable
states; hence bistable).
Monkeys can be trained to report which of the percepts they are
currently experiencing.
By looking for cells that fire only when a certain percept is
reported, neuroscientists can get an idea of which cells are involved
in generating the subjective experience (the stimuli themselves are
perfectly constant).
NCC Experiments (cont.)
Unconscious action:
Milner and Goodale have shown convincingly that much action
is guided without subjective experience.
By examining the precise kinds of damage and the reports of
patients, it may be possible to use this to discriminate between
unconscious and conscious visual information processing.
Patients with ventral damage can catch a ball, but don't have a
normal experience of a round object coming at them (and can
interact with but not report the angle of a slot).
Bistable Percepts
?
NCC Hypothesis
Given this data, C&K think that frontal areas are where the NCC is most
likely to be found
This is where visual information can be used to control voluntary action.
Prediction: a person with no frontal areas wouldn't have conscious visual
experience.
This hasn't been confirmed, but monkeys who have had large frontal
lesions act completely blind.
As well, fMRI of blindsight patients shows that frontal areas (46 & 47)
are active only when the patients report a 'slight' visual experience.
Other NCC suggestions:
Thalamus (Sejnowski)
Cortical Waves (Llinas)
40Hz oscillations (Crick and Koch, earlier)