How To See The World: Part Two


(Part One ended with Professor Mirzoeff having introduced the famous Fellemen and Van Essen visual pathway circuit-like diagram.)

“The diagram suggests a visual parallel with one of the great modernist paintings: Piet Mondrian’s 1942 classic Broadway Boogie Woogie.   Here the Dutch artist adapted his neoplastic aesthetic to express his sense of jazz-era New York.

piet-mondrian-14-638

The painting conveys the dynamism of the grid city of Midtown, as well as its unexpected vibrations and drama that make the urban experience anything but regular.  Boogie-woogie was an up-tempo piano form of the blues, often accompanied by a spectacular form of jazz dane that centre on a back-and-forth between the dance partners.

In the painting, the combination of repeated bass rhythm and staccato dance movements evocatively conveyed the affect of the machine age.  If we take the liberty of making a formal comparison between this painting and the 1991 depiction of vision (recognizing that they come from very different contexts), we can see in both cases how vision has gone from being the single decision imagined by Descartes to the dynamic experience of the modern, machine-based city, conveyed by its flickering lights, back-and-forth journeys, and infectious music.

In his analysis of this depiction of visual processing, the celebrated neuroscientist V. S. Ramachandran highlights the importance of the feedback between stages:

Note especially that there are at least as many fibers (actually many more!) coming back from each stage of processing to an earlier stage as there are fibers going forward from each area into the next area higher up the hierarchy.  The classical notion of vision  as a stage-by-stage sequential analysis of the image, with increasing sophistication as you go along, is demoished by the existence of so much feedback.

It is not just up to the judge.  To extend my metaphor, it’s the interplay between city residents on the street, the way the dancer responds to the piano, the feeling of being part of something.  The information goes back and forth from one level to the next, filling in pieces as it goes.  So, it is (for now) settled: seeing is something we do .rather than something that just happens naturally.  More precisely, we need to set aside the persistent notion that an image gets relayed from the retina to the brain – the retina is itself part of the brain where, in Ramachandran’s words, ‘the rays of light are converted into neural impulses.’  From that point, the information is distributed and processed in a series of parallel steps that continually reinforce the other layers.  What we used to call an image is now known to be a computation, even in the brain.

descartes_diagram_of_ocular_refraction-_wellcome_l0012003

In the current model, we don’t even “look” to see.  In Descartes’s version, the judgment presided over seeing, making it seem a very deliberate process.  In fact, there are three kinds of unconscious eye movement involved in seeing.  Convergence movements direct both eyes to the same place.  Pursuit movements track moving objects.  Within these overall ways of seeing, research has shown that the building block of close seeing is the saccade, a spontaneous scanning by the eyes that move from one point to the next.  Saccades are very rapid.  Saccades can be set off voluntarily, as when we direct our eyes at a painting.  Or they can be involuntary, in response to a moving object, a noise, or any other unexpected event.  So, the old idea of a single gaze or look, fixing people or objects under its stare, has to be modified.  Our eyes are always busy, boogieing back and forth.  The resulting mental ‘image’ that we ‘see’ remains stable because the brain computes it that way.”

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