Download Philip Buss - the IDeA Lab!

Philip Buss Page 1
Philip Buss
12-9-06
Fletcher
Scientific Study of Consciousness
Term Paper
Consciousness: What Good is it?
In recent years, a strong emphasis has been put on discovering the origins of
humans through the study of evolution. People are intrigued by the idea that their
extremely complicated bodies evolved from lower life forms through a completely
natural process. Now, this idea is being applied to the human mind in the form of
evolutionary psychology. How was our consciousness created through natural selection?
A more fundamental question is “Why was it created?” The theory of natural selection
says that our bodies were designed for optimal functionality. Therefore it is only
reasonable to say the same of our minds. This subject, however, is much harder to study;
there are no fossil records directly indicating the evolution of the mind. This paper will
examine some possible explanations for how and why the mind was created, focusing on
neurobiological evidence as well as the role of social developments on the creation of the
modern mind.
The study of brain processes has given scientists some useful insights into how
and why the mind evolved. Multiple lesion studies of the human visual system have
revealed an extremely intriguing fact; as stated by Cristof Koch, “there are two – at least
two – visual systems in your head…One is for conscious seeing, and one is for doing
visual-motor actions” (Moffett, 2006, p. 81). An example of this is the phenomenon
Philip Buss Page 2
known as blind-sight. Blind-sight is the unofficial term for people who are technically
blind and yet show signs of some visual capacities. The neuroscientists Milner and
Goodale have done extensive research on patients with different types of brain damage
which have altered their visual systems. (Milner, Goodale, 2004). The first patient,
named Dee Fletcher, received brain damage from carbon monoxide asphyxiation. Dee is
unable to recognize objects, even though she is able to “see” color and texture. This form
of blindness is called visual agnosia. Despite her being incapable of identifying
(perceiving) objects, her motor responses to visual stimuli are perfectly normal. She is
able to navigate around objects when walking, accurately pick up objects, and post her
hand through a rotatable slot (Milner, Goodale, 2004, p. 18-20).
Another patient, studied by neurologist Rudolph Bálint in 1909, suffered brain
damage due to a massive stroke (Milner, Goodale, 2004, p. 32-33). This man’s disorder,
called optic ataxia, is fundamentally opposite Dee’s. He has perfect perception, in that he
can see objects and accurately describe them as well as their orientation in space. In
other words, his visuospatial skills are intact. However, when told to pick up an object in
front of him, he shows complete incompetence. He gropes “blindly” toward an object
which he can see perfectly. His visuomotor abilities are completely impaired. A very
interesting discovery was made in a recent experiment performed on a patient with optic
ataxia. When the patient was asked to point to spots of light flashed on a screen, she was
very inaccurate, as expected. However, when asked to wait for five seconds after the
flash had come and gone, she was much more accurate (Milner, Goodale, 2004, 80-81).
This remarkable result demonstrates that this patient’s motor abilities are only restricted
when asked for an immediate, reflexive response. When asked to wait and consciously
Philip Buss Page 3
plan it out, she didn’t seem to be impaired. The act of planning and internally visualizing
where the spot had been must have used separate brain processes than the ones normally
used in quickly responding to visual stimuli.
These two case studies reveal that there are indeed (at least) two visual systems in
the brain. The first is the one responsible for conscious perception (which was absent in
Dee Fletcher) and the second is responsible for motor responses to visual stimuli (absent
in Bálint’s patient). Using fMRI scans, scientists were able to determine that the
processes in the brain which lead to conscious perception are located in what is called the
ventral stream, while the processes leading to motor responses are in the dorsal stream.
The dorsal stream leads from the occipital cortex up over the top of the brain to the motor
strip, which controls body movements. The dorsal stream has been called a “zombie
system,” meaning it leads to motor responses without needing any conscious perception.
The ventral stream, however, is conscious, because it leads to more complex
representations (conscious perception and awareness). The ventral stream, which runs
from the occipital cortex along the bottom of the brain, goes through more complicated,
specialized brain structures such as the fusiform gyrus (responsible for facial recognition)
and the amygdala (responsible for raw emotions) and eventually connects to the temporal
lobe, where memories can be formed. The ventral stream appears to be more
sophisticated than the dorsal stream, and seems to contain many of the elements of
consciousness. Why then is it necessary (or useful) to have two separate systems?
Neuroscientist Umberto Castiello found in his experiments on reaction time that
the dorsal stream acts much faster than the ventral stream (Blackmore, 2004, p. 39-40).
Philip Buss Page 4
Reflexive actions occur well before any perception occurs. According to Cristof Koch
and Francis Crick,
“It is a good evolutionary strategy…to have some fast, stereotyped
reactions and processes in addition to a slower, integrative function like
consciousness. With such a schema, consciousness can react to new and
evolutionarily unanticipated circumstances while not having to dirty its
hands with the mundane work of survival, which it can leave to the
zombie modes” (Moffett, 2006, p. 81).
In this interpretation, the dorsal steam developed first and was responsible for simple
reflexes like running away from a predator or avoiding an object while walking. The
ventral stream evolved later, and is capable of overriding the hardwired dorsal reactions
in special circumstances. In most instances, the visuomotor reaction is good enough to
handle the situation. However, more complicated scenarios may necessitate the use of
conscious thought. Animals with such abilities would have been better able to survive,
thus selecting for the possession of these two visual systems. Still, why should we have a
conscious and an unconscious system? Why not just have a single, more capable
conscious one?
Neurobiologist John Allman relates this dilemma to a power plant he visited in
the 1970s. He was surprised to find that the plant was controlled not by a single, modern
computer system, but by multiple systems, including outdated technology run on vacuum
tubes. He asked if it wouldn’t be more efficient to have a single, more advanced system
(the answer is undoubtedly yes). However, he was answered “that the demand for power
had always been too great for the plant ever to be shut down” (Milner, Goodale, 2004, p.
Philip Buss Page 5
47). Due to the high demand for power, there was never any time to shut down and
redesign the whole system. This is very similar to the two systems in the brain.
Originally, there was only the dorsal stream. Then, due to the evolutionary benefits of
having conscious perception, the ventral stream was added on top of it. There was never
any time to “overhaul” the whole system; simply more hardware was added. This is why
we still have an unconscious aspect of vision. The next question we must ask is, “If
consciousness is such a useful invention, then why are its capabilities so limited?”
Even though consciousness has many valuable uses, it is limited to “one-thing-ata-time.” Bernard Baars, a proponent of the Global Workspace Theory of consciousness,
asks us why the brain, which is capable of such complex processes, can only consciously
handle one thing at a time. Baars answers that a human cannot have two conscious
representations at the same time because consciousness is a global message to the entire
nervous system, and only one such message can be present at a time (Baars, 1988, p. 348,
350). This is similar to what Antonio Damasio has termed the “movie-in-the-brain.”
“This ‘movie’ is a metaphor for the integrated and unified composite of diverse sensory
images…that constitutes the multimedia show we call mind” (Damasio, 2002, p. 7). Our
consciousness is undeniably “seamless” in its depiction of the world around us. We
cannot really be aware of two things at once. Crick and Koch believe that “it may be
more efficient for the brain to have ‘one single explicit representation,’ once and for all,
rather than sending information, in tacit form, to many different parts of the brain”
(Blackmore, 2004, p. 246-247). The reasons for having a single unified conscious
experience are strictly functional. It is important for a person to have one complete
representation of the world rather than multiple fragmented ones. Otherwise, it would be
Philip Buss Page 6
very difficult to make a coherent picture of one’s surroundings. So far, only the
neurobiological aspects of conscious development have been discussed. Now we will
move on to the social aspects of this.
It is easy to see the benefits of unconscious brain processes. As put by Steven
Pinker, “You don’t need an evolutionary biologist to tell you that depth perception keeps
an animal from falling off cliffs” (Pinker, 2002, p. 52). It is trickier, however, to see the
purpose of consciousness:
“But with other aspects of our mental life, particularly in the social realm,
the function of a faculty is not so easy to guess. Natural selection favors
organisms that are good at reproducing in some environment. When the
environment consists of rocks, grass, and snakes, it’s fairly obvious which
strategies work and which ones don’t. But when the relevant environment
consists of other members of the species evolving their own strategies, it is
not so obvious” (Pinker, 2002, p. 52).
Social developments complicate natural selection – the actions of one organism affect the
life of another. The basis of natural selection is the passing on of successful genes from
one generation to the next. If all organisms are devoted only to themselves and their
families (similar genes), how is it that complicated social interactions such as cooperation
evolve? The simplest answer is that cooperation must aid the individuals in passing on
their genes. There is no “greater good” - this is only an illusion. Any ecosystem consists
of a bunch of independent organisms trying to procreate. All social developments such
as cooperation, non-violence, and monogamous relationships must somehow benefit each
organism involved. Furthermore, these developments require the ability to perceive and
Philip Buss Page 7
understand other organisms (conscious perception) and then to use that ability for
personal gain. The advent of social interactions likely created a large demand for new,
more integrated and more flexible processes, which eventually materialized as
consciousness. In an ecosystem filled with competing organisms, the ability to
understand this environment is extremely beneficial.
According to Pinker, another reason why consciousness must be useful is that
conscious organisms have it from birth. Consciousness is not “learned” or “formed”.
There obviously has to be a survival benefit to possessing consciousness, for “[i]f our
minds were truly malleable they would be easily manipulated by our rivals, who could
mold or condition us into serving their needs rather than our own” (Pinker, 2002, p. 5455). Therefore consciousness must have some inherently useful properties which are
present from birth.
Despite the benefits of having consciousness, it is possible for simple organisms
to live perfectly well with nothing but zombie processes. Why is it then that humans are
so dependent on consciousness for survival? Daniel Dennett claims that simple
organisms have “no need for consciousness” (Moffett, 2006, p. 214). However,
“once creatures started to move around and interact with each other,
creating more complicated problems for themselves and one another,
Mother Nature (‘otherwise known as the process of evolution by natural
selection’)…began to come up with more complicated solutions to give
her offspring a leg up in the fight for survival” (Moffett, 2006, p. 214).
In other words, the advent of social interactions necessitated the ability to anticipate,
sense, and plan, all of which are constituents of consciousness. While zombie processes
Philip Buss Page 8
work well enough for the survival of a single organism by itself, the complications
arising from interactions with other organisms require something more. Now that we
have seen some reasons for consciousness, let’s look at when it may have evolved.
Surely there must be some point at which animals first attained conscious thought.
Unfortunately, this is sort of like the “chicken or egg” predicament. Daniel Dennett
“doesn’t think there’s a clear place where you can draw a line above which everything is
conscious and below which everything isn’t” (Moffett, 2006, 214-215). Since we can’t
come up with a clear distinction, let’s try a broader perspective. William Calvin is
confident that the human mind was shaped into what it is today during the short periods
between ice ages. According to Calvin “climate is fickle; ‘sudden-death playoffs’ can
happen within a matter of a decade or so. Abrupt climate change makes versatility, often
a virtue, a necessity” (Calvin, 1991, p. xiv). As we saw with the ventral stream in visual
processing, versatility is one of the main benefits of consciousness. Calvin points out that
somewhere in the period of shifting ice ages, hominids turned into humans. His theory is
that it was during the short “boom times” in between ice ages that humans developed
large brains (and subsequently consciousness.)
In this essay, we explored various reasons for having consciousness, as well as
how it might have come into being. Studies of the visual system have shown us the
usefulness of conscious perception as well as why we have two separate processing
streams for visual stimuli. We have also seen why the brain strives to create a single,
unified experience (movie in the brain) – it allows a coherent representation of the
environment to form. We then looked at how the advent of social interactions sparked
the beginnings of consciousness. Finally, we put it in perspective by giving a theory on
Philip Buss Page 9
when this emergence took place. Consciousness is perhaps the last great biological
mystery. Despite its deep involvement in our lives, its function is still largely mysterious.
One philosophy, known as mysterianism, says that complete understanding of the human
mind is unattainable. I, however, feel that with enough people dedicated to studying it,
the mysteries of consciousness may one day be revealed.
Philip Buss Page 10
Bibliography
Baars, Bernard. A Cognitive Theory of Consciousness.
New York: Cambridge University Press, 1988.
Blackmore, Susan. Consciousness an Introduction.
Oxford: Oxford University Press, 2004.
Calvin, William. The Ascent of Mind.
Bantom Books, 1991.
Damasio, Antonio. “How the Brain Creates the Mind”. Scientific American. 2002: 4-9.
Goodale, Melvyn; Milner, David. Sight Unseen.
Oxford: Oxford University Press, 2004.
Moffett, Shannon. The Three-Pound Enigma.
New York: Algonquin Books, 2006.
Pinker, Steven. The Blank Slate.
New York: Penguin Group, 2002.