Eco-Optics: When Vision Goes Green


test_duochrome“Keep ’em in the green and they’ll keep you in the green” is an old expression that was commonplace in teaching clinics when I was cutting my teeth in Optometry.  This refers to the practice of making sure that patients, particularly those who are nearsighted, have a distance prescription that leaves them slightly favoring the ease of seeing black letters in a green background in contrast to black letters in a red background.  My purpose here is not to debate the merits of this practice, but to point out an entirely different aspect of vision – one that is rarely addressed by eye doctors in the course of examination.

That aspect involves movement.  Invariably every aspect of vision assessment during an “eye examination” involves stationary targets, with a sedentary patient.  Even if one could make the argument that increasingly our days are occupied by sitting in front of a computer screen scanning print (what are you doing now?), a considerable amount of time is still spent getting from place to place.  Think of walking or driving for adults, at the very least, yet alone the visual world of the developing child.  We need better tools with which to assess patients during an examination that reflects visual demands in the natural environment.

Ecological Perception - GibsonMy argument here is that we need a new construct for keeping patients in the green, and that green does not represent clarity of distance sight, but efficiency of visual ecology.  Ecology is the study of our interaction with the environment, and in that sense our traditional way of assessing visual function isn’t very eco-friendly.  Perhaps the closest we come to recognizing this is in the development of test procedures to assess the athlete in “Sports Vision” evaluations.  But why not broaden this thinking to every patient for, after all, we each have needs involving either dynamic visual scenes and/our own own movements as we use our eyes and visual systems.  The psychologist J.J. Gibson can be credited for championing this approach, and his most comprehensive treatment of the subject was in his book on The Ecological Approach to Visual Perception.  It is a book, as Gibson notes in his introduction, about how we see in our natural environment.  His notion of what he terms an ambient optic array displaces the more narrow idea of vision as based on a retinal image.  Gibson first used the term, Ecological Optics in an article in Vision Research way back in 1961 to convey this idea.

By the way, when Gibson mentions the ambient optic array that may ring a chord with the distinction made between ambient and focal vision.  Although this concept is often credited to Trevarthen, it was really Gibson’s work on ecological optics and perception that set the stage for Trevarthen’s work.  I can see that I’m going to need a few more parts to this blog to adequately elaborate, but let me leave you with this thought.  We’ve reviewed many times before than vision is a collaboration between the eyes and the brain.  Gibson goes further.  He writes:  “We are told that vision depends on the eye, which is connected to the brain.  I shall suggest that natural vision depends on the eyes in the head on a body supported by the ground, the brain being only the central organ of a complete visual system.  When no constraints are put on the visual system, we look around, walk up to something interesting and move around it so as to see it from all sides …”  To Gibson, ambient vision involves looking around, and ambulatory vision involves active exploration.  He finishes his introduction by noting that the examination procedures in ophthalmology and optometry require the patient to hold his eye fixed like a camera, obtaining good facts used in determining eye health and prescribing “corrective spectacles”.  He argues the case compellingly that there is so much more.  How is it that Gibson has been overlooked for so long?

This question was posed to me by Sue Barry, whose idea it was to re-visit Gibson’s work, apply it to her personal experiences, and use it as the framework for our upcoming presentation.  She is the catalyst for many of the ideas that we’ll be visiting through eco-optics.

jj gibson

10 thoughts on “Eco-Optics: When Vision Goes Green

  1. Thanks Len,
    James Gibson is incredibly influential to me and how I evaluate the visual system. I routinley assess visual acuity while the patient is in motion: “dynamic visual acuity.” I hope you write about his wife Elenor! As you know, she coined the term “Perceptual Learning.” We as Developmental Optometrists are of the few clinicians in the world who understand the optical, physical and neurological foundations for perceptual learning to occur, and how to ensure that this blend of abilities synchronize into higher level cognition.
    Carl

  2. You’re welcome, Carl. Certainly dynamic visual acuity begins to scratch the surface, and I will address that in Part 2. I will also write something about Eleanor. She is most famous to us from her experiments on The Visual Cliff. Actually she and JJ both used the term perceptual learning, and both should get credit for introducing it. Although she wrote the seminal book with the title in 1969, JJ may have actually published using the term first, witness this title of a book chapter he contributed in 1953: “Social perception and the psychology of perceptual learning.” He and Eleanor co-authored a paper in 1955: “Perceptual learning: Differentiation or enrichment? Pschol. Rev. 62:32-4. At some point I want to go through the OEP papers and see if there is any acknowledgement of Gibson’s work. Gibson from what I can tell made no mention of behavioral optometry, and Eleanor no mention of developmental optometry, even though both fields would have seemed to inform their work. This is a gap that may be plugged at least in retrospect. Thanks again for taking the time to read, reflect, and comment!

  3. Bravo for all of your insights and taking the time to share with the rest of us! I am a fan of trial frames, and walking the patient not only around the office but often outside to evaluate the efficacy of a potential prescription. I wish I had time to take them driving…

  4. Dear Lenny,

    Thank you for your insights regarding a dynamic versus static approach to vision. Some thoughts in response to your stated comments. The concept of red/green interpretation during the subjective has often been referred to as a Binocular Balance. Ironically, many doctors do not know whether or not their patients are actual binocular since they had not even done a test of stereopsis. They also totally ignore our visual functioning at near and/or at a computer distance. In regards to movement, our eyes are in constant motion. Although our world is perceived by us as a continuous picture, we are processed it in small chunks in a discontinuous manner. Despite our current limitations, it is truly amazing that we can actually determine an appropriate prescription for most patients, which solves their most glaring problem, a reduction in sight while the patient is sitting in a chair looking out at infinity. The newer technology is continuing this emphasis on acuity and refractive error. As we become a more near point oriented society, it is time to look beyond this age long misperception. In other words, we may be treating a symptom(s) without dealing with the underlying problem(s), which is common place in our health care system. Myopia is certainly a common refractive condition, which we have seen increase in occurrence and degree rather than preventing or controlling its progression. It is certainly time to reassess our testing and treatment protocols. A dynamic versus static and/or a movement component are certainly factors to consider in this paradigm shift. Unfortunately, I do not SEE this change occurring very rapidly. Thank you again for your another thought provoking blog.

    Richard

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s