Biology 202

2006 Book Commentaries

On Serendip

Antti Revonsuo's Inner Presence: Consciousness as a Biological Phenomenon is a through investigation into the brain behavior dynamic explored in class, but also tackles issues posed by thus statement in greater depth. With far ranging topics from the similarities of dreams and pain to the issues of synsethysia, her model gains validation through her discussion of different states of consciousness, as well as her readiness to discuss other theories. While her discussion of alternative theories often leaves her own point less clear and understandable, it elevates the status of her book from simply a new theory to a resource on consciousness. Inner Presence is a valuable, if not elaborate, discussion of how consciousness is essential to human existence, and its implications philosophy, psychology and neurobiology.

Instead of posing an I function to be consciousness, Revonsuo subdivides consciousness. There is the primary, phenomenal consciousness which is "the immediate presence of qualitative experience for a subject." This structure places perception of the self in an environment as primary, creating an egocentric view. Revonsuo sums up the "subjective phenomenal consciousness [as] a real, natural biological phenomenon that literally resides within the confines of the brain" where "to be real is to have causal powers" (pg 10)
The "center-periphery organization" places a specific phenomenal content at the center of consciousness, while everything else exits in the background, or periphery of consciousness.
The absence of consciousness, the unconscious and nonconscious, are different in their connection to consciousness. The former "can in principle modulate consciousness and thus exist in phenomenal form, whereas nonconscious in the brain cannot directly modulate phenomenal consciousness nor exist in a phenomenal form at all." For example, a significant event in the past can influence a person's conscious

A critical component of perception is a sense of presence, "the sense that [a person shares] a common spatial and temporal framework with objects in [their] presence." This opens up a framework in which hallucinations and dream experiences are congruent with those of waking consciousness. In this world-simulation model, the brain creates a representation of the world which it can interpret. The simulation is based on what the nervous system is able to perceive. This theory, called representative realism, holds that there must be a real world outside of our perceptions that "exists independently of our experiences and representations of it." (121) We perceive the world indirectly, through how it affects our bodies and then how our brain interprets these interacts.
One of the implications of perception in the representative realism model is that the reliability of perception is put into jeopardy. It is easy to fall into a cycle of skepticism, since our perceptions can be fooled, as demonstrated in class on many occasions. It also causes a logical regression which is problematic. We perceive something, but how do we perceive ourselves or perceive to perceive perception? This semantic discussion is useless, as the author points out.
The further discussion of perception stems from a concept called biological realism, which is used almost interchangeably with the term world simulation metaphor. Biological realism emphasizes as biological, rather than metaphysical or psychological approach to brain and consciousness. It condones the view that brain is the same as behavior. But it does not shy away from theoretical discussions of the implications of biological realism.
If brain and behavior is equal, then what would happen if brains were simply located in vat. The brain would be fully functional, yet in complete isolation from normal sensory and motor connections and instead given some form of artificial or internal stimulation. For instance, the internal stimulation could be similar to that which is perceived during dreaming. In this scenario, there are no causal connections between the brain and outside reality. This is not unfeasible, since during dreaming we "turn out to be brains in a natural biological vat." (139) Yet if a brain is in an artificial vat, can the person be said to be dead or alive? Biological realism states that a person is still alive with normal conscious experiences.
But, Revonsuo continues, then one could not argue that a person artificially created was not as alive as a naturally produced person. A person could be replicated in exactness, and be just as alive and human as one that has been alive for many years. In addition, this means that experiences do not actually have to be experienced personally. Instead, if a brain was replicated, it could be said to have the same experiences as the original. Finally, then brains could be replicated without bodies and still experience consciousness. This thought process leads to validation of AIs as having a human consciousness if the organization is similar to a human nervous system.

The Sensorimotor Theory of Consciousness refutes biological realism. (141) It denies that experiences are occurrences that have qualitative properties. Experiences are "ways of acting" or "something we do", "and the qualitative features of experience are aspects of this activity." (141) Vision is the ultimate in "sensorimotor contingencies." Consciousness is based on actions, or behaviors, unlike biological realism where action is not necessary. The Sensorimotor Theory rejects the possibility of brains to exist without interacting with its environment. Consciousness is not located within the brain, thus brain activity does not give rise to experience. Therefore there is also no subjective experience at a basic level in the brain and instead located at a higher behavioral level.
Another theory of consciousness is that consciousness cuts across the brain-body-world division, instead of being concentrated in within the neural circuitry of the nervous system. Called the Radical Embodiment of Consciousness, leaves a location for consciousness vague or where the science of consciousness should focus. Revonsuo rejects this theory for its obscurity and its impartibility. She states that radical embodiment "confuses the internal spatial relations and locations within the phenomenal level with those of the external physical counterparts of the phenomenal entities."(143)

Touching upon the topic of color, Revonsuo explores the implications of David Foulkes' direct realism not only on perception, but also on consciousness. Direct realism implies that people experience objects in the world directly. Color is a direct observation of a physical property of a physical object. Color is not, in the direct realist view, a psychological product generated within the brain. Modern studies of color have generally rejected direct realism, yet it still has some support. Revonsuo is unclear in her handling of this material, not coming to a significant conclusion or connecting it to the greater idea of phenomenal consciousness. She raises some interesting questions, however, which were also raised in class. Her discussion of color comes back to the problematic issue of reality. Regardless of the location of consciousness, it has been repeatedly shown that people's perception of color is relative and susceptible to illusions. Revonsuo does nothing to tackle these issues and gets clouded in dealing with specific theories.

Inner Presence is admirable for tackling a wide range of topics, providing extensive defense for the theory of biological realism and the importance of phenomenal consciousness. As a book, it is more useful as a reference guide rather than a complete theory. However, the theories which Revonsuo proposes are penetrative and insightful, if not already covered through Paul Grobstein's Neurobiology and Biology.


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