Your Beautiful Eyes

Neurophysiology of the Eye/Brain System – Dr. Nikos Salingaros

Starting from a light-sensitive spot on protozoans and primitive worms capable of judging direction, the primitive eye developed a sense for various degrees of light intensity so as to perceive distance, or the shadow of an aggressor. Movement detectors, requiring first and second derivatives of the signal in time, were among the first to appear during evolutionary development. Finer and finer tuning corresponds to an increase in the brain’s information channels and capacity. Researchers believe that the brain developed concurrently with the eye in order to handle the increasingly complex optical information input from the evolving eye (Fischler & Firschein, 1987). Some accept the co-evolution of the left/right reversal of functions int he two brain hemispheres, and the left/right reversal of an optical image on the retina, as proof of the concurrent evolutions of the eye and brain.

Geometrical uniformity is decoupled from our neurophsyiology, because a majority of cells in both the retina and visual cortex will not fire in response to a uniform field (i.e., an empty region with no identifiable features) (Hubel, 1988). Visual receptors in the retina (either single cells, or groups of cells) compare the characteristics of adjacent regions–they spatially differentiate the signal. Color wavelength is determined by comparing the output from three different types of cone cells due to the response from a single point. Neurobiologists have identified specialized neurons and clusters of neurons that perceive angles, curvature, and contrast (Hubel, 1988). The latter work via lateral inhibition (i.e. signal comparison) and are successfully simulated in artificial (compuational) visual system to achieve edge detection (Fischler & Firschein, 1987). The eye/brain systems is thus idle in a visually homogeneous environment, the lack of stimuli reducing the need for activity.

Particular brain cells, and some groups of cells, have a preference for all possible oblique orientations in addition to vertical and horizontal. The directional preference of successive cells in a cortical region distinguishes between angles of 10 to 20 degrees (Hubel, 1988; Zeki, 1993). The existence of orientation-specific cells in the visual cortex proves the importance of angular information, since such a cell will fire only when confronted with diagonal lines at the particular angle the cell is created for. None of these neurons will fire in a strictly rectangular environment, thus diminishing the sensory connection to it.

In addition, “end-stopped” cells in the visual cortex respond to lines of a distinct orientation up to a small maximum length, beyond which their response drops to zero. These are neurons that exist only to recognize detail and differentiation. End-stopped cells are biological receptors that are directly sensitive to corners, curvature, and to discontinuities in lines. All these brain cells are again inactive in a visually homogeneous environment. Our brain works much like a scanner, which spend the bulk of it processing energy copying the highly detailed areas of an image.

More impressive is the finding of individual neurons in the cortex that are optimized for complex shapes. Experiments show that such cells preferentially fire when presented with complex symmetrical figures such as concentric circles, crosses with an outline, stars of various complexity, and other concentrically-organized areas of contrast (Zigmond, 1999). Furthermore, these neurons coexist with “silent surrounds”, which help the neuron to recognize a complex figure better when that figure stands out in a plain background. From all appearances, our brain as ornament recognition built right into it.

Our eye/brain system evolved to perform a very specific function, and this suggests that human beings, as the animals that can create the greatest variety of physical structures, reproduce in artifacts what stimulates our brain directly. It is no coincidence that the elementary ornamental elements mentioned above appear on pottery, bone designs, non-representational paintings, and textiles over a period of several millennia (Washburn & Crowe, 1988). Early people represented visual aspects of their environment in an effort to codify it, and thus gain better control over it. Symbolic representations aided in ordering elements of cultural and physical landscapes, and therefore helped to understand the unknown.

Neurophysiological findings link our ability to recognize ornament with our evolutionary development. Complete visual information is processed hierarchically int he brain, moving through different regions in succession. Two features point to increasing complexity. First, as one progresses forward into the brain’s major processing pathway, there is a progression of the complexity and the critical visual detail needed to activate certain individual neurons (Zigmond, 1999). That is, as one progresses into the more advanced regions of the brain, more complex patterns are required as visual input before certain neurons will respond. Second, the relative numbers of neurons that are selectively driven by a complex pattern increases.

Minimalist surfaces and edges negate the way human beings have evolved to process information. It is know that when we go against our neurophysiological make-up for whatever reason, then our body reacts with physical and psychological distress. Such effects are measurable, and include raised blood pressure, raised level of adrenaline, raised skin temperature, contraction of the pupils –all symptoms of triggering our defensive mechanisms against a threat. When it recognizes a threat, the eye/brain system initiates physiological actions in order to protect the organism. Stress is an adaptive reaction to disease, injury, or toxins. The same mechanism extends to cope with unpleasant sensory input from the environment (Mehrabian, 1976).

The opposite effect -depression- results from under-stimulation. Studies of sensory deprivation show that we require above a minimum threshold of informational load from our environment in order to function normally (Mehrabian, 1976). I would like to see more experiments to measure human physiological response to different architectural environments. Already, studies by environmental psychologists tend to confirm what is proposed (Klinger & Salingaros, 2000). Depressing work environments are a result of poor architecture. Conversely, people are more productive in environments rich in ordered fractal information such as is provided by trees and plants.

Degradation of our ability to see fine detail signals the onset of different pathologies of the eye itself rather than the brain. The first group of problems occur with the lens – either the lens can no longer focus, or it becomes opaque due to a cataract. The second group of problems have to do with the retina; in particular, with the macula, the central region of the retina where cone cells that are responsible for seeing fine detail and color are concentrated. The retina can be damaged by detachment, or the macula can degenerate because of inadequate blood flow. The loss of visual information cuts us off from our environment, and creates anxiety by lowering our ability to respond to it. These pathologies make us experience normal, informationally-rich environments as if they were minimalist environments.

All of this strongly suggests that we become uneasy in architectural settings where we experience a reduction of perceptual or cognitive input. This is unsettling because the circumstances of being unable to define our surroundings makes us feel helpless and lost. Those environments mimic signs of our own pathology. Are we subconsciously reminded of a failure of our visual system when we spend time in a minimalist environment? Such a response is probably so deeply-seated that it can only be overridden via a concerted conscious effort, if at all.

The brain has novelty detectors, which have alerting functions as consciousness. Unfamiliar patterns of constructs (not found in nature or traditional artifacts) trigger an immediate response that is physiologically based. This makes sense given our evolutionary development, which had to learn to protect us from potential dangers. People who are taught (i.e., have had to be trained) to look at novel constructs without alarm have undergone psychological conditioning, which establishes aesthetic preferences that contradict their basic instincts.