01/23/02
S. David Stoney, Ph.D.

Sensation and Perception: A Process Approach

"The brain's business is representing other things." Antonio R. Damasio, How the brain creates the mind, Sci. Amer. 281: 112-117, 1999.

"There is no notion more crucial to the study of thought and cognition than representation." John Grush, The architecture of representation, Philos. Psychol. 10: 5-23, 1997.

"When we describe ourselves as 'sentient' beings (from Latin sentire, 'to feel,' from Indo-European sent-, 'to head for,' 'go'; hence to go mentally) we mean that we are conscious. The more literal and encompassing meaning is that we have sense perception. It is both our panic and our privilege to be mortal and sense-full... We live on the leash of our senses. Although they enlarge us, they also limit and restrain us, but how beautifully. Love is a beautiful bondage, too." Diane Ackerman, A Natural History of the Senses, NY: Vintage Books, pgs. xvii-xviii, 1990.

"The basic point, in contrast with the superficial empiricism of sensationism, is that sensory perception is not the basic form of perception...Perception is, in fact, one of the universal variables, exemplified to some degree in all events.  Hartshorne often uses Whitehead's term 'prehension' to refer to this primordial, root form of perception, in which the present experience feels the feelings of previous experiences, thereby taking the previous events as objectified into itself...this nonsensory prehension is the root of sensory perception." David Ray Griffin, Charles Hartshorne, In: Founders of Constructive Postmodern Philosophy: Peirce, James, Bergson, Whitehead, and Hartshorne, Albany, NY: SUNY Press, pg. 208, 1993.

"The entity of which we become aware in sense perception is the terminus of our act of perception...Perception is simply the cognition of prehensive unification; or more shortly, perception is cognition of prehension." Alfred North Whitehead, Science and the Modern World, New York: The Free Press, pgs. 70, 71, 1925.

"A Whiteheadian will gladly acknowledge that feeling occurs within the neural system, that is, prehensive grasping of prior organic states by new moments of nascent actuality. Information is recognized, reacted to, processed, and passed on. Presensory perception, unconscious but essential to any sensation as it travels from event to event toward awareness, is the underlying requisite for sensory cognition. Immediate experience, it turns out, floats on depths of presensory - thus extrasensory - perception. The dogma that cognition can be accounted for on the basis of the five senses alone is blind to the kind of experience that precedes, surrounds, and makes possible the five senses themselves. A postmodern epistemology will not be intimidated by such dogmas." Frederick Ferre, Knowing and Value: Toward a Constructive Postmodern Epistemology, Albany, NY: State University of New York Press, pg. 279, 1998.

"...the nervous system is in no sense an apparatus which may serve to fabricate, or even to prepare, representations." Henri Bergson, Matter and Memory, 5th Ed., New York: Zone Books, Translated by Nancy M. Paul and W. Scott Palmer, pg. 31, 1996/1905.

"The theory that brain function is naturally subdivided into such entities as sensation, perception, motivation, emotion and memory is not consistent with the findings of neuroscientific research." C.H. Vanderwolf, The behavioral neurobiology of learning and memory: a conceptual reorientation, Brain Res. Revs. 19:264-97, 1994.

"...if we are correct in our analysis, there is need for reassessment, on the part of neuroscientists, of the notion of neural correlate of consciousness. A way of thinking about the neural bases of perception and action is needed that does not rest on the false assumption that the brain is the seat of consciousness." J. Kevin O'Regan & Alva Noe, A sensorimotor account of vision and visual consciousness, Beh. Brain Sci. 24, 2001.

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As Diane Ackerman suggests in the quotation above, to be sentient implies that we are able to feel and be consciously aware of self and world.  As I have previously mentioned,classical neural theory (CNT) separates sensing from feeling, strongly emphasizing the former while considering the latter to be a secondary aspect of perception dependent on late-stage neural processing in the limbic lobe of the brain. The figure above schematically diagrams the steps in sensation and perception according to CNT.

 The figure at the right may be of some help for those of you who have not been doing much thinking about the mind-body problem<1>.  It depicts the most popular modern schemes.  The last scheme (C), which I refer to as "neuralism," is the nihilistic, solipsistic deconstructive postmodern one adopted by many contemporary scientists, where mind is considered to be identical with the activity of brain, period <2>.  I would argue that such "identism" is a form of dualism in denial <3>, where the "Cartesian cut" is now between the inside and outside of the human body.
 
 
 
 

I much prefer an alternative (Whiteheadian or Harshornean; process philosophical; reconstructive postmodern) perspective, one which is more compatible with actual human experience as well as with quantum theory <4>.  In this perspective, mind is seen as distributed between brain, body, and world, which are all fundamentally interconnected via a capacity for experience.
 

 Process philosophy, posits experential events as the final, "real stuff" of the universe, rejecting the idea that "mere" matter occupying otherwise empty space is fundamental.  See <5> for details as to the nature of experiential events.  Process philosophy suggests that two fundamental processes occur during perception: First, a unification of 'feelings' of the knower and the object of knowledge.  Whitehead called this process a "prehension" or "nonsensory perception" or "perception in the mode of causal efficacy." This process, which is a kind of taking into account of the interiority of subject and object, is mostly non-conscious and non-local and it reflects the quantal wholeness of the universe.  Hartshorne described prehensive unification as a "feeling of feeling."  The second step in perception, "perception in the mode of presentational immediacy," is the one we are most consciously aware of, the one that seems to be most neurally dependent and which we refer to when we use the term "sensory perception."  Such sensory perception is, in fact, as Whitehead said, "perception of prehension." Although it is somewhat natural to presume that sensory perception is neurally dependent while nonsensory perception is not, this is not the case.  Neurons prehend each other and (for some) sensory receptors.  Sensory receptors prehend supporting cells and, in some cases, energy from the environment.  There is, in addition, prehension of the objects of the environment by all the cells of the body, including nerve cells.  So neurons are part and parcel of prehensive networks and may take part in both the nonsensory and the sensory processes underlying perception.  The figure below shows my attempt to diagram this "Ecological Neuroscience" view of perception.
 
 

One of the problems of the materialistic approach of neuralism (CNT) is that there is no basis for deciding why only one type of neuron, e.g., cortical neurons, contribute to conscious awareness whereas others, e.g., spinal cord neurons, do not.  The process philosophical approach of ecological neuroscience avoids this problem by positing that the mind (psyche, or soul) is the dominant occasion of experience of the prehension beween brain, body & world.  That is, at the onset of any experiential event, mind is co-extensive with brain, body, and world, and shares the experiences of all the actual occasions that constitute these entities. As compound organisms, our conscious awareness is the compounded experience of the totality of these actual occasions.  This is often described as the mind, or psyche, prehending the brain, a description that has a decidedly dualistic cast and which obscures the fact that experience supervenes on matter.  It is more correct to say that mind is in prehensive relation with all the cells of the body, including its neurons, as well as the actual occasions of the world, and integrates their experiences as conscious perception.  Mind is, in fact, a dynamic singularity of body, brain, and world <5>.
 

I like this approach because it seems to avoid solipsism, it accepts that we each have a dominant occasion of experience that participates with the dominant occasion of experience of the universe, which is the ultimate source of the creativity that is expressed in the coming into being of each actual occasion, and it is more compatible with a responsible approach to self, world, and others than is the approach due to CNT. It also seem more compatible with modern aspects of biology (evolution) and physics (quantum theory). Copies of some papers about the process philosophy of A.N. Whitehead and Charles Hartshorne can be found on reserve at the library [Neuroscience (ITD5170) , Dr. Stoney].  Meanwhile we shall mostly focus on the CNT approach since it is so widely accepted.

References and Notes

1. The current status of the mind-body problem according to CNT was succinctly stated in a recent, authoritative neuroscience textbook:

 "We as yet do not know how the firing of specific neurons leads to conscious perception even in the most simple case.  In fact, according to [the philosopher, John] Searle, we completely lack an adequate theoretical model of how an objective phenomenon - electrical signals in a person's brain - can cause a subjective experience such as pain." Eric R. Kandel, From Nerve Cells to Cognition: The Internal Cellular Representation Required for Perception and Action, In: Principles of Neural Science, 4th Ed., Eric R. Kandel, James H. Schwartz, & Thomas M. Jessell (Editors), New York: McGraw-Hill, pg. 397, 2000.

2. With regard to contemporary neuroscientists, consider this quotation from a leading neuroscience textbook:

"Most neuroscientists and philosophers now take for granted that all biological phenomena, including consciousness, are properties of matter.  This physicalist stance breaks with the tradition of dualism stemming from ancient Greek philosophy.  The break...focuses the problem of consciousness for the twentieth century neuroscientist.  Philosophically disposed against dualism, we are obliged to find a solution to the problem in terms of nerve cells and neural circuits...We are optimistic that future cognitive neural scientists will identify the neurons involved and characterize the mechanisms by which consciousness is produced."  James H. Schwartz, Consciousness and the Neurobiology of the Twenty-first Century, In: Principles of Neural Science, 4th Ed., Eric R. Kandel, James H. Schwartz, & Thomas M. Jessell (Editors), New York: McGraw-Hill, pgs. 1318 & 1319, 2000.
     Concerning certain important distinctions between deconstructive postmodernism and the reconstructive postmodernism advocated by those who adopt the process philosophical perspective, consider the following comments by David Ray Griffin in his introductory remarks for the SUNY series of books on "Constructive Postmodern Thought," for which he serves as Editor:
"From the point of view of deconstructive postmodernists, this reconstructive postmodernism will seem hopelessly wedded to outdated concepts, because it wishes to salvage a positive meaning not only for notions of selfhood, historical meaning, reason, and truth as correspondence, which were central to modernity, but also for notions of divinity, cosmic meaning, and an enchanted nature, which were central to premodern modes of thought.  From the point of view of its advocates, however, this revisionary postmodernism is not only more adequate to our experience but also more genuinely postmodern.  It does not simply carry the premises of modernity through to their logical conclusions, but criticizes and revises those premises.  By virtue of its return to organicism and its acceptance of nonsensory perception, it opens itself to the recovery of truths and values from various forms of premodern thought and practice that has been dogmatically rejected, or at least restricted to 'practice,' by modern thought.  This reconstructive postmodernism involves a creative synthesis of modern and premodern truths and values." David Ray Griffin, Religion and Scientific Naturalism: Overcoming the Conflicts, Albany, NY: SUNY Press, pg. xii, 2000.
     Concerning the extraordinary scope and timely utility of the process philosophical approach, consider:
"Through Whitehead's category of prehension - the nonsensory sympathetic perception of antecedent experiences - we are able to reduce several apparently very different types of relations to one fundamental type of relation.  The category of prehension explains not only memory and perception, which seem different enough at first glance, but also temporality, space, causality, enduring individuality (or substance), the mind-body relation, the subject-object relation in general, and the God-world relation." David Ray Griffin, Charles Hartshorne, In: Founders of Constructive Postmodern Philosophy: Peirce, James, Bergson, Whitehead, and Hartshorne, Albany, NY: SUNY Press, pg. 209, 1993.
     For more information on prehensions see http://david8.home.mindspring.com/Website/Whitehead_Prehensions.htm

3.  See, for example, these two interesting papers.  C. H. Vanderwolf, The behavioral neurobiology of learning and memory: a conceptual reorientation, Brain Res. Revs. 19:264-97, 1994; and M.R. Bennett and P.M.S. Hacker, Perception and memory in neuroscience: a conceptual analysis, Prog. Neurobiol. 65: 499-543. Bennet and Hacker discuss how the "philosophical idiom associated with the Cartesian tradition... has been transferred from the mind to the brain:"

"Why... was this form of description, and the attendant forms of explanation that are dependent upon it, adopted without argument or reflection? We suspect that the answer is - as a result of unthinking adherence to a degenerate form of Cartesianism. It was a characteristic feature of Cartesian dualism to ascribe psychological predicates to the mind, and only derivately to the human being. Most contemporary neuroscientists, however, reject this dualism - quite rightly. But the predicates that Cartesianism ascribes to the mind, the present generation of neuroscientists apply unreflectively to the brain instead."

4.  See, for example, Henry P. Stapp, Mind, Matter, and Quantum Mechanics, NY: Springer-Verlag, 1993. In a recent personal communication, Professor Stapp stated:

"The nonlocal aspects of quantum theory also support a self-image of man as more than just a complex structure of mud-like matter: he is more deeply integrated into nature than that: his every thought has ramifications throughout the universe..."
     For a consideration of the applicability of process philosophy to modern physics see Jungerman's book:
"Thus, the vacuum - the space between atoms and within atoms - is not empty, but continually and spontaneously filled with the birth and death of virtual particle pairs.  This is happening in the air around us and within our own bodies.  The vacuum is really filled with events - the fundamental entities of process thought.
     The empirical fact is that the world is nonlocal: that is, events in a certain space-time region can indeed affect those in another space-time region and not be constrained by the demand of the theory of relativity that no signal may exceed the velocity of light...This interconnectedness is difficult for us to understand since there is no similar experience in our macroscopic world unless telepathic contact is an analogue.  Such interconnectedness is a fundamental concept of process philosophy, wherein each event is connected to all past events." John A. Jungerman, World in Process: Creativity and Interconnection in the New Physics, Albany, NY: SUNY Press, pgs. 86 & 87, 2000.

5. See, for example, S. L. Hurley, Consciousness in Action, Cambridge, MA: Harvard University Press, 1998.