How Is Your Liver Today?

As we continue the shift from sight to visual perception, our attention must move to the brain.  Watch your step, please.  Most lay people, like myself, find the central role of the brain in visual perception to be almost counterintuitive.  

I exaggerate the role of my eyes in visual perception while forgetting the starring role of my brain.  That should not be surprising.  I am aware of my eyes throughout my waking hours.  I blink, I squint, and I seek better light or try to shade my eyes from too much light -- all in an effort to create the most meaningful personal visual experience.  My eyelids are even the “switch” by which I turn my vision "on" in the morning and "off" a night.

I usually think of my brain about as often as I think about my liver – almost never. They both operate faithfully without my awareness and they only signal me in the direst of circumstances.  Assuming that you have a healthy brain and liver, you probably know what I mean.   

How will we tackle the brain?   It might be interesting if we located key regions of the brain that are involved in visual perception along with the logic of key neurological connections.  Alternatively, we could skip all that and follow the brain's key tasks in visual perception.  I prefer the second approach.  We will examine some things more closely but the real payoff seems to be in "thinking like the brain" as it tries to construct a coherent 3-D awareness and understanding of the scene around us. 

Finally, here are three sources for valuable information. Two of them are entirely free. 

The first is a website  operated by the University of York. You must register for this site but it is free.  There are a number of simple illustrations or short animations regarding visual perception.  The content is divided into 15 separate broad topics such as Anatomy and Physiology, Color, Depth, Illusions, Motion, and Abnormalities.  Most topics have several related presentations.  Many of the presentations are interactive Flash movies. 

One of the contributors to Viperlib, Tutis Vilus, teaches at the University of Western Ontario.  He has his own website as well where he posts excellent and absolutely free teaching materials about visual perception (Flash movies, PDF versions, and other useful information).  He actually offers these materials from two different courses:

The Physiology of the Senses

The Neurophysiology for Medicine                                                  

Both sets make excellent use of Flash -- interactive and with sound.  The second set is a bit more advanced and oriented to clinical issues.  It still contains useful information for “the rest of us” and you can pick and choose as you wish.  My big point about all of these online teaching sources is that the interactive animations are great for learning dynamic topics like vision.   

The third source is a book: Vision Science – from Photons to Phenomenology, by Stephen E. Palmer.  This is my go-to favorite “textbook.”  The writing is semi-technical but very clear. Palmer does a terrific job presenting the material from multiple disciplines in layers.  There are even two tables of contents.  He also suggests a clear hierarchy of steps the brain uses to create a coherent visual perception of 3-D space.  This hierarchy is very useful in thinking about a field of such breathtaking complexity.  Palmer says it best: "Were it not for the fact that our brains manage to come up with the correct solution most of the time, it would be tempting to conclude that 3-D visual perception is simply impossible!" 


The Palmer book is large – over 2 kilos, 800 pages, and pricey -- $80.  If you want a definitive book on this field, start here.  If you get it from Amazon, of course, you have a 30-day return policy. 



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