Abstract
This paper demonstrates that the human visual system, the primary sensory conduit for primates, processes ambient energy in a way that obligatorily constructs the objects that we ineluctably perceive. And since our perceptual apparatus processes information only in terms of objects (along with the properties and movements of objects), we are limited in our ability to comprehend ‘what is’ when we move beyond our ordinary world of midsize objects—as, for example, when we address the micro microworld of quantum physics.
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Notes
As G. M. Edelman and G. Tononi (2000), pithily express the first aspect of such qualified realism: “Being precedes describing.” (p. 175) And in terms of the highly restricted samples of ambient energy that are processed by brains of always limited capacity, they note “that there is no judge in nature deciding categories except for natural selection…” (p. 207)
Here is how E. Sober and D.S. Wilson (1998) express this point: “Burden of proof is a legal and procedural concept, designed to protect the right of this or that party (e.g., the accused). It simply has no place in argumentation whose goal is to figure out what is true. In law courts, the burden of proof falls on the prosecution; in science and philosophy, it falls on everyone. When evidence is indecisive, we should admit that it is and not invoke a spurious tie-breaker.” (p. 288)
By vertical “end-stopped” object, I am referring to what appears to us as a discrete object that does not continue upward like, say, a tree trunk, and yet that is more solid than, say, the less distinct distribution pattern created by undergrowth.
Computational capacity is constrained not only by “housing space” availability within an organism but also by energy requirements. So, for instance, although the present human brain weighs only about 3 pounds (less than 2% of an average sized man), it uses more than 20% of the body’s total energy.
For a more detailed discussion of this point, including additional instances involving more complex animals, see P.R. Sullivan (2005), Part I.
Bipolar cells, horizontal cells, and amacrine cells intervene between detector cells and ganglion cells, modulating input, but we do not have to consider this complication in order to make the present point.
Nerve fibers from retinal ganglion cells actually end in a cluster of neurons in the thalamus called the lateral geniculate nucleus. It is these cells that send direct messages to the striate cortex of the occipital lobe. But since the topography of the external visual field is maintained all along the path to the striate cortex, the way I have stated the case makes the point in suitably simplified fashion.
Because the relatively early computational processes just described are sufficient to indicate the obligatory nature of visual object formation—our present goal—we will stop short of surveying the many computational refinements added to these early stages. For instance, as data continues to be processed in more anteriorly placed regions of the cerebrum, including the ventral and lateral occipito-temporal cortex, object constancy is achieved independently of precise physical cues (e.g., changing the angle or distance from which the visual array is being viewed). In the case of some categories like faces, class-specific modules come into play, whereas many other items are processed by more general-purpose mechanisms (See K. Grill-Spector, 2003, for a clear review of this more refined arena of brain activity.).
In order to interpret results of the ‘double-slit experiment’, it may be useful to review the nature of interacting waves (imagining water waves will be helpful). Whenever two waves merge at their peaks, the resulting wave will be much larger in size. By contrast, when the trough of one wave merges with the peak of another wave of equal size, the two will cancel each other out, a phenomenon aptly referred to as interference. The original ‘double-slit’ experiment goes back to 1804 at a time when the question of whether light consisted of particles or waves was being hotly disputed. A physician, Thomas Young, projected a stream of light through a single narrow slit. As one might expect, a bright and slightly broadened image of the slit appeared on the opposite wall (compatible with the notion that particles of light were landing on the wall, more in the center, but some angling through the slit to either side). But then he opened another narrow slit very close to the first. This time the result was more surprising, for the wall now showed an alternating pattern of bright and dark stripes. This was precisely the sort of pattern that would be expected if light waves passing through the two slits were in turn amplifying and interfering with each other.
Often, popularizers of quantum physics have attempted to explain this micro-microworld in ways that are fully congruent with our ordinary world of midsize objects. For instance, the atom continues often to be represented in solar-system format, its nucleus analogous to the sun, its electrons visualized as discrete planets circling their “sun” at a distance. This oversimplified model is then used to provide a logically understandable explanation for Heisenberg’s “Uncertainty Principle.” Heisenberg had noted that one can never simultaneously know both the precise location of an electron and its momentum. Imaginatively visualizing this situation as if we were dealing with objects from our ordinary world, the following explanation provided an illusion of comprehensibility in terms of that ordinary world: The electron circling its nucleus has a mass so small that any probe used to hit it (hence, locating its position precisely at the time of collision) will at the very least nudge it off course, changing its momentum. While this explanation validly addresses one of the technical problems involved, it nevertheless provides an intellectually comforting scenario at the cost of falsely visualizing the electron in terms of an ordinary particle from our ordinary world of midsize objects. Part of the weirdness (to us) of quantum reality is that the electron is not equivalent to some miniscule pool ball, a discrete entity whose size, together with its location on the pool table, could be accurately determined if only we had a sufficiently diminutive tape measure. The electron is not a particle in this sense (in fact, like the photon, it also may be viewed as a “wavicle”).
The phenomenon is not an actual contradiction. This would require the same thing to be so and not so at the same time under the same conditions, whereas the “whatever” that is involved differs under different conditions. It is the reason for this different manifestation of the same “thing” that remains inherently conundrumous for us.
This estimate comes from The MIT Encyclopedia of the Cognitive Sciences (2001); but since there is no sharp line of demarcation between visual processing and multimodal information-processing in the brain, 50% amounts to a conservative figure.
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Sullivan, P.R. Objects limit human comprehension. Biol Philos 24, 65–79 (2009). https://doi.org/10.1007/s10539-008-9117-y
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DOI: https://doi.org/10.1007/s10539-008-9117-y