Wednesday, July 31, 2013

The Knowledge of Ignorance

My work as a research optical engineer involves the intersection of lasers and human vision. Recently, this prompted me to take a look at what is frequently referred to as the Stiles-Crawford effect. Although the effect was discovered back in the 1930s I read a much more recent review of the history of this discovery and its subsequent development.

W. Stanley Stiles first began his experiments investigating the glare effects of looking into oncoming headlights while driving at night. While the glare and its attendant problems were his primary concern he stumbled onto a totally unexpected feature of the human visual system along the way. Although I won't go into what may be for you totally boring details of the effect, suffice it to say that has to do with the highly directional light sensitivity of the retina's cone cells. Of course, these cells are the ones that are primarily responsible for the eye's ability to discriminate color and to detect small details. 



Visual Interface, © Bill Brockmeier
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While the effect itself is very interesting to me personally from a number of different aspects, what most caught my attention was that 80 years later those closest to this problem still have no conclusive understanding of its mechanism. It is simply amazing that with all of the modern biological microscopic imaging, high powered computer modeling and such that this simple effect still escapes a clear definition as to its cause.

The article went into some detail concerning modeling work that had been done over recent years to "prove" a waveguide theory as the basis of the effect's operation. This work has shown the theory to be inconclusive at best. Other theories were likewise recounted in the review, as were their shortcomings.

The review delved deeply into very minute details of the structure of the cone cells– how they are organized, and how they most likely function. An incredible level of understanding currently exists of what goes on in these tiny detectors of light, and yet, this understanding does not yet provide a full picture of how an effect discovered nearly a century ago fundamentally works. Perhaps a full and accurate explanation lies just around the corner...or perhaps not.

It seems that regardless of one's pursuit in life, the more one understands about it and the more expert we become, the more we understand our own ignorance and how little we really know. Deep and real knowledge always seems to bring with it a strong dose of humility. 

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