The Sensory Value of Ornament. /Nikos A. Salingaros/* *Department of Applied Mathematics, University of Texas at San Antonio, San Antonio, Texas 78249, USA. E-mail: salingar@sphere.math.utsa.edu */For: Communication & Cognition (2003)./* /Ornament is a valuable component in any architecture of buildings and cities that aims to connect to human beings. The suppression of ornament, on the other hand, results in alien forms that generate physiological and psychological distress. Early twentieth-century architects proposed major stylistic changes -- now universally adopted -- without having any idea of how the human eye/brain system works./ ------------------------------------------------------------------------ 1. Introduction 2. Visual meaning 3. How the eye scans a picture 4. Neurophysiology of the eye/brain system 5. Visual ordering and patterns 6. Hierarchical cooperation 7. Color and intelligence 8. The value of ornament 9. Ornament and writing 10. Conclusion ------------------------------------------------------------------------ 1. Introduction. This paper argues that ornament is valuable for us to experience architectural form in a positive way. An earlier article (Salingaros, 2000) presented mathematical reasons for why ornament is necessary. The visual coherence of a complex form, as defined by systems theory, requires ordered substructure on all scales: from the overall size of the building, down to the detailed grain in the materials at 1 mm. Natural structures have this (fractal) property. If a man-made form lacks ordered structure on one or more obvious scales, it is perceived by human beings as being visually incoherent, and consequently as alien to our conception of the world. A building's substructure on the range of scales from 1 mm to 1 m is usually achieved via traditional ornament. Our neurophysiology is set up so that we expect visual input from our surroundings to contain many of the characteristics of traditional ornament. Human visual and mental make-up is linked through evolutionary processes to the informational richness of our environment. This biological background will help to explain some aspects of why human beings create ornament. Going deeper than the usual "artistic" analysis of architectural ornament, I try to place it within the context of shared biological mechanisms. I present several rules derived from our cognitive apparatus -- these rules are intended to help understand how we conceive a form as visually coherent. I then discuss the relationship between cognitive rules and the creation of ornament. I propose two arguments against the minimalist and random design of built forms. The first is that they cause anxiety and physiological distress, because they inhibit human beings from connecting mentally with a given structure through meaningful information. This point will be discussed at length. The second concern is the resemblance between minimalist or disordered built environments, and the perception of a normal, visually complex environment by persons with a damaged perceptual apparatus. I shall indicate how different types of injury to the eye and brain result in precisely the same effects offered by either minimalist or intentionally disordered design. The broader implication is that human architecture requires ornament for emotional well-being. To prove this is outside the scope of the present paper. I acknowledge other factors that influence the appreciation of architecture, including past experience, cultural formation and environment, and upbringing. Other authors argue for innate preferences for certain types of landscape, giving convincing reasons. At the same time, however, it has been shown that innate preferences are displaced by factors such as familiarity and conditioning. Therefore, it is probably true that living one's life in a minimalist architectural environment will make one more familiar with it. Even so, I don't believe that such types of structure are in harmony with our neurophysiological make-up. 2. Visual meaning. A form's visual organization communicates information to people through the surfaces and geometry it presents. Environmental experience is based upon an intimate interaction of human beings with surfaces and spaces, which influences our emotions and physiological state, and consequently our actions. A building's exterior and interior surfaces either "connect" in an emotionally positive manner with the user; remain neutral by having no effect; or act in a negative fashion so as to repel. This connection resides in the information content of space and its transitions. Even though surface qualities are usually assumed to be separate from the spatial geometry in a building, the two are in fact interdependent, and both contribute to how people respond to their surroundings. Traditional architecture uses organized information to establish a positive connection. Throughout history, nonfunctional architectural components were deemed necessary for a building to offer a pleasant environment, and thus to enhance its attractiveness and use. Moldings, color, decoration, and richly-textured materials serve this purpose. Traditional architectural environments are inconceivable without such psychological design enhancements. In the twentieth century this connective mechanism was suppressed so as to focus on pure geometrical form. Nevertheless, the emotional link established between people and built structures led us, through feedback, to produce traditional ornamented structures. Human emotional response is based on neurophysiology and information input. It cannot be undone for the sake of a particular architectural design style that eschews ornament. An environment lacking in texture, color, and ornament can be punishing for a human being, as exemplified in the design of prisons throughout history. Going to the other extreme, an environment that is supercharged with /uncoordinated/ visual stimuli -- such as the Las Vegas strip lit up by neon lights -- exceeds the visual input that can be consistently tolerated. We seek meaning from our environment and are repelled by environments that convey no meaning, either because they lack visual information, or because the information present is unstructured (Klinger & Salingaros, 2000). Information has driven our evolutionary development: human vision and intelligence increased our capacity for processing information. The eye and the brain form a single mechanism (Hubel, 1988). Design is itself a product of human vision and intelligence, therefore the complexity of traditional designs parallels cognitive structures of the human brain. This observation makes the underlying reasons of why we build complex things less mysterious. People are motivated to build so as to extend their consciousness to a wider domain outside their own mind. 3. How the eye scans a picture. In classic experiments on human eye motion while scanning a picture (Hubel, 1988; Noton & Stark, 1971; Yarbus, 1967), the eye is observed to focus most of the time in the regions of a picture that have the most detail, differentiations, contrast, and curvature (the experiments referred to did not include color). These are clearly the high-information regions in the picture. Eye fixations establish a fairly narrow "scan path" where the eye spends about one-third of its time, with random excursions to low-information (i.e. plain) regions of a visual. The brain thus selects informative details such as convoluted, detailed contours and contrasting edges for recognizing and remembering an object. Our visual system is built to select those items of concentrated information that can provide the most complete response in the shortest possible time. The information content of visuals lies precisely where the eye spends its energy scanning; the rest of the picture is easily reconstructed by extrapolation (Nicolis, 1991). This is how the brain stores information via a compression algorithm. Selective weighting of information to minimize coding also provides the basis for information storage in artificial systems such as computer graphics (Klinger & Salingaros, 2000). We comprehend an object by seeking to define its boundaries and any characteristic internal details. Note, however, that a discontinuity or sharp interface such as occurs when two edges come together has no width or dimension, and so does not provide any detail. A precise straight edge has no information. The more complex a curve is, the more information it contains. Detail is nothing more than contrast on the smallest scales. In principle, therefore, contrast (coupled with hierarchy) includes detail. Nevertheless, as the concept of hierarchical scales is not so widely known, I will continue to discuss contrast and detail as separate entities. There is another reason why our eye/brain system has evolved to perceive detail, and that is our capacity to predict future events (Llinás, 2002). An intelligent, mobile animal focuses on details that give crucial information about an adversary during combat; about changing physical conditions crucial to survival; the recognition of familiar animals and their facial expression; visual cues from a prey being hunted; etc. All of this information comes directly from telling details. Our cognitive system normally has no time to process all available visual information in those instances, and has to rely on first input in order to make almost instantaneous decisions. Recent work (VanRullen & Thorpe, 2002) suggests that a first, rough image is created using only the salient parts of a retinal image -- that is, regions of high contrast and detail. In this first wave of signals, it is contrast that encodes sufficient information to make a decision on our need to respond. The rapidity of this first image, which is entirely subconscious, is faster than our motor response time. This is an absolutely necessary feature, which makes possible a rapid response to any potential threat while the full image is still being processed. Our "instinctive" response to a form is therefore based on contrast and detail. Further information from the retina is processed more slowly, and any kind of rational analysis of the form can begin only after the retinal image itself is completed. First response depends on an incomplete image that somehow has enough detail for recognition. With more processing time, the image progresses to evolutionary higher levels of the midbrain, where single neurons can recognize complex wholes. Islands of such neurons capable of sophisticated pattern recognition exist at the same level as islands of neurons responsible for seeing fine detail. Detail is thus an evolutionary advanced skill that the brain has developed over time. The above considerations suggest two cognitive rules on how we perceive our world. I propose that artificial structures ought to in general follow such rules, precisely because our perceptual apparatus has evolved to use them. The understanding is that our cognitive mechanism implies analogous rules for constructing the man-made world. */Rule 1. Every structure ought to have some subregion with a high degree of contrast, detail, and curvature. Those correspond to high values of the first and second spatial derivatives./* */Rule 2. Plain surfaces require either their interior, or their borders, to be defined through contrast and detail./* Large, plain objects or surfaces disturb the observer by presenting no information -- the most disturbing being surfaces of glass or mirrors that prevent the eye from even focusing on them. We instantly look for reference points, either in a form's interior, or at its edge (Zigmond /et. al./, 1999). We need to comprehend a structure as quickly as possible, to make sure that it poses no threat to us. Large uniform regions with abrupt, ill-defined boundaries such as an infinitesimally thin line generate psychological distress (which then has physiological consequences) as the instrument -- namely, the eye/brain system -- seeks visual information that isn't there. This frustrates our cognitive process. Rule 2 reminds us of the principles involved in message transmission. In sending a message, it is necessary to indicate its limits. For example, a one-dimensional piece of information needs to be identified as such by noting where it begins and ends. This requires additional coding for the message's boundaries. Without those boundaries, the receiver has no idea of what it is receiving, and cannot distinguish a message from other portions of a signal. In ordinary writing, a sentence begins with a capital letter and ends with a period. In any computer language, encoded text -- even if it consists of no words at all -- is always bounded by BEGIN and END tags. 4. Neurophysiology of the eye/brain system. 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. Finer and finer tuning corresponds to an increase in information channels. 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 in the two brain hemispheres, and the left/right reversal of an optical image on the retina, as proof of this. Uniformity is decoupled from our neurophysiology, because a majority of cells in both the retina and visual cortex will not fire in response to a uniform field (Hubel, 1988; Zeki, 1993). 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 (computational) visual systems to achieve edge detection (Fischler & Firschein, 1987). 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. In addition, "end-stopped" cells in the visual cortex respond to lines of a distinct orientation up to some maximum length, beyond which the response drops to zero. End-stopped cells are biological receptors that are directly sensitive to corners, curvature, and to discontinuities in lines, and this supports Rules 1 and 2. More impressive is the finding of individual neurons (in cortical area V4) 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 /et. al./, 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 has ornament recognition built right into it. I therefore propose: */Rule 3. Our visual attention is immediately attracted to elementary ornamental elements, such as symmetric stars, concentric circles, crosses with an outline, etc./* Our eye/brain system evolved to perform a very specific function, and this suggests that human beings, as those among the animals that can create 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 several millennia (Washburn & Crowe, 1988). Neurophysiological findings link our ability to recognize ornament with our evolutionary development. Visual information is processed hierarchically in the brain, moving from the Primary Visual Cortex forward into the Inferior Temporal Cortex (through areas V1, V2, V3, V4, TEO, and TE, 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 internal detail needed to activate certain individual neurons (Zigmond /et. al./, 1999). Second, the relative numbers of neurons that are selectively driven by a complex pattern increases. Minimalist surfaces and edges violate the way human beings process information. It is known that when we go against our neurophysiological design 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. 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, however, extends to cope with unpleasant sensory input from the environment (Mehrabian, 1976). The opposite effect -- depression -- results from understimulation. Studies of sensory deprivation show that we require a minimum informational load from our environment in order to function normally (Mehrabian, 1976). I would like to see specific experiments to measure human physiological response to different architectural environments. Already, studies by environmental psychologists tend to confirm what is proposed in this paper (Klinger & Salingaros, 2000). 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. All of this suggests -- although it does not prove -- that we become uneasy in architectural settings that 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 be overridden, if at all, only via a conscious effort. The brain has novelty detectors, which have alerting functions as consciousness. One has to learn to look at novel constructs -- i.e., to undergo psychological conditioning before establishing aesthetic preferences that contradict their basic instincts. 5. Visual ordering and patterns. Rules 1, 2 and 3 explain the necessity of visual information. Now we turn to the opposite problem: the case when there exists too much information. The first three rules are by themselves not sufficient to explain the geometry of form, since they say nothing about how visual information may be ordered. We know very well, however, that our cognitive system craves structured information and is overloaded with disordered (i.e. random) information. Ordering via patterns is discussed in (Klinger & Salingaros, 2000), where a complexity index is used to measure visual coherence. This leads to additional rules that govern how visual information can be organized. The easiest way to group information is along some curve. */Rule 4. Visual information can be ordered efficiently via linear continuity./* This corresponds to the simplest possible expedient of lining up high-contrast objects on end; not necessarily in a straight line, but on some sort of curve. The units do not need to repeat to be connected as in Rule 4. What this lining-up does is to significantly narrow the scan path that the eye needs to follow in order to grasp the information encoded in the components, since now there are fewer excursions to farther regions. Lining-up corresponds to a condensation of two-dimensional information. It is probably no accident that we read text that is organized on a line. Also, artists know the advantages of a pencil line sketch in capturing information -- as in a quick portrait sketch -- as opposed to the more difficult task of representation by means of shaded areas without abstracted linear information. There exist other techniques of organizing information spatially without condensing it along a line. The alternative is to organize high-information units using symmetry, which leads to patterns in space. A further savings of effort is accomplished in visual compression, by repeating a similar unit. Repetition can give rise to the wide range of traditional symmetries, such as reflectional, rotational, translational, and glide symmetries (Washburn & Crowe, 1988). High-contrast objects on the small scale can be spatially arranged in a symmetrical pattern, and the smaller units made similar so as to cut down the total amount of information. */Rule 5. Symmetries and patterns organize visual information, significantly decreasing the computational overhead./* A well-defined unit that is repeated does not need to be processed by our cognitive machinery each time anew. We apparently have the means to recognize similarity very easily, so the eye/brain system can encode a pattern in terms of one or more basic units, plus their positional distribution. If the units are repeated in some symmetric fashion -- i.e., the units' positions are themselves symmetric -- then only a little additional information is needed to specify the pattern. For this reason, patterns tend to be preferred over a random distribution of repeated units (Klinger & Salingaros, 2000). In the absence of any symmetry or ordering, our eye/brain system has to compute the position of each unit separately, which increases effort and comprehension time. Organization endows structural information with meaning, which in turn connects that object with the human mind without the need for conscious reflection. Here is where hierarchy, the topic of (Salingaros, 2000), comes into play in an essential manner. A symmetric arrangement of units is perceived on a higher level of scale than the units themselves. Together, the smaller units define some pattern -- a cognitively coherent unit that has more information than its components alone. As soon as one starts to do this, then recursion can be applied to define increasingly higher levels of scale, with each coherent arrangement on a particular level being very easily comprehended. This nesting of patterns within patterns has occupied mankind for millennia (Washburn & Crowe, 1988). One could even claim that it forms a significant percentage of creative output over the history of the human species. It is seen in architectural ornament (especially Islamic), oriental carpets and traditional textiles, geometric designs on pottery, etc. Readers will undoubtedly note a relationship between the cognitive rules and the Gestalt laws (Fischler & Firschein, 1987), as follows. Rule 4 relates to "Proximity" and "Good Continuation", while Rule 5 relates to "Similarity", "Closure", and "Symmetry". Failure to perceive patterns indicates a pathology of the brain; in particular, the failure of different specialized regions and mechanisms that process visual information to integrate their functions (Zeki, 1993). Specific causes of such disintegration include Carbon Monoxide poisoning and cerebral lesions due to strokes. In what is known as "visual agnosia", a person perceives detail but cannot integrate this information to recognize an overall form. This could be manifested as an inability to recognize objects or faces. Such persons can see but cannot understand their environment, and the trauma makes them anywhere from mildly to severely dysfunctional. Agnosic patients can draw an artifact so that others can recognize it, but which they themselves don't. They are found to copy pictures strictly according to their local structure, without a grasp of the global structure, i.e., the overall shape (Zigmond /et. al./, 1999). Their drawings lack an overall coherence, and they will classify two pictures differing in only a minor detail as different objects. Some patients with brain damage complain that their environment appears fragmented; components are isolated and they cannot discern any meaningful spatial relationship among them. I conjecture that, presented with an environment that deliberately breaks patterns and large-scale visual coherence, human beings will instinctively react in a manner similar to an internal loss of integration. 6. Hierarchical cooperation. In order to identify exactly what it is that successful ornament achieves, I need to discuss the many ways it serves to connect and integrate. The first way is the most obvious one -- ornament connects spatially separated regions by giving them a mathematically similar surface. That is, using the same ornamental design on opposite walls connects them in the mind of the observer. This is an application of translational symmetry. Without an identifiable similar design somewhere on them, two surfaces are not likely to appear as connected. The second way in which ornament connects is through hierarchical cooperation. This is a term used in (Salingaros, 2000) to summarize part of what is a fundamental theory of "wholeness" developed by Christopher Alexander (2003). In the previous section, I mentioned how patterns within patterns define different scales of structure. The existence of a hierarchy of scales is not sufficient, however. The different scales must cooperate visually in order for the ensemble to appear coherent. One way to achieve this is to have scaling symmetry, in which a design is repeated at a higher magnification. The eye/brain system thus perceives a connection between the two different scales. Practical methods of hierarchical cooperation utilize scaling properties of fractals (Mikiten /et. al./, 2000). This plays a fundamental integrative role. Linking different scales in this manner serves to make a large-scale structure appear internally coherent. It also provides an easy point for /external/ connection at every scale. Since all scales are supposed to be connected to each other, then a person connecting to one scale will immediately connect to /all/ the scales. This is the purpose of the mechanism -- to make possible an effortless human connection to a structure defined on several different levels (Mikiten /et. al./, 2000). These points may be summarized by two rules: */Rule 6. Coherence occurs when each scale is related to many different scales -- it is often necessary to introduce new structures on the smaller scales to create a hierarchy of connected scales. /* */Rule 7. Human beings connect to their environment on a number of different scales, and the connection is strongest when the environment is visually coherent./* Human beings establish a special rapport with artifacts that have been formed by the human hand -- or with natural objects that exhibit substructure on that range of scales 1 mm - 1 m. The exact reasons are not known. One can guess, however, that it has to do with the more intimate matching of scales that the human body itself possesses, and is also influenced by a far more important role for the tactile sense than is usually assumed in discussions of aesthetics. Since tactile connections exist purely on the smallest scales, this favors the smaller scales in the total scheme. A study of the neurophysiological mechanisms whereby we connect to our environment reveals that concurrent processes operate at different scales (Mikiten /et. al./, 2000). The visual cortex is organized in a hierarchical fashion, and signals proceed up the hierarchy through a "processing stream" (that goes from cortical areas V1 to TE) (Zigmond /et. al./, 1999). At the same time, at all stages in the pathway, connections tend to be reciprocal, feeding back processed signals from later regions (which respond to complex visual stimuli) into earlier regions (which respond to basic stimuli such as edges and orientation). This creates an iterative loop among hierarchically-organized clusters of neurons that parallels the linking among the components of a hierarchically-organized complex pattern. I emphasize connectivity and integration because I believe it to be a central factor in experiencing our environment (Mikiten /et. al./, 2000). Coherence at all scales is perceived as "beauty". Descriptions of this effect are found more in philosophy and religion rather than in science -- a harmonious environment is considered connected on all scales, and we experience peace (i.e. psychological and physiological well-being) when we ourselves connect to it. Once we establish what is behind this effect, then we can analyze the various mathematical methods that are responsible for connectivity. Although there is insufficient experimental confirmation on this topic, it is believed that intelligence, thought, reasoning, and consciousness, are emergent properties -- products of an enormous number of ordered connections. Intelligence is measured by our ability to establish a connection between thoughts. Drawing a very broad analogy between neurons, individual thoughts, and physical structures, we mimic our own mind when we create internally-connected objects and buildings. While this conclusion is conjectural, it nevertheless offers a way of understanding the human urge to connect designs on artifacts and the built environment in many different ways. It helps to explain our instinctive need to integrate or "harmonize" our surroundings. Rodolfo Llinás (2002) posits that 40 Hz coherent oscillations observed in the brain are related to consciousness. He offers this mechanism as one possible explanation of the observed phenomenon of spatial coherence, in which different groups of perceptual functions interlock. Perceptual unity links together independent sensory components, in what is called "cognitive binding". This represents a synchronous neuronal activation during sensory input. It is indeed observed that neural mechanisms operating independently in the spatial domain, each responsible for separate processing of sensory stimuli, link physiologically. Whether it is driven by the observed 40 Hz oscillations or not, cognitive binding is incontrovertible. The breakdown of integration, when it occurs in our own brain due to a pathology, diminishes our ability to function at the level of a human being. It is not clear what happens when an analogous breakdown is intentionally imposed on the built environment, by suppressing both perceptual components, and the possibility of their integration. I cannot help but think that willfully disconnecting a sentient being from surfaces and structures has strongly negative implications. 7. Color and intelligence. Color vision represents a significant information increase over monochromatic vision found in otherwise intelligent animals such as dogs and cats. The sensation of color resides just as much in the computational part of the brain as it does in the optical mechanism of the eye (Hubel, 1988; Zeki, 1993). This is shown by "color constancy", which is the ability of the eye-brain system to adjust a biased color illumination and reconstruct a faithful color image. In the experiments of Edwin Land, a color painting or collage illuminated by red, green, and blue lights together appears the same to us regardless of the relative intensities of the three different lamps used for illumination. Color photographs of an object under different lights, however, look very different. Color perception evolved to support higher cognitive processes occurring in the human brain (Llinás, 2002). This is shown by the well-known evolutionary tradeoff between sensitivity to dim light, which is necessary to detect movement, and sensitivity to color, which is useful for identifying and classifying objects. For most animals, it is more important to be able to /detect/ objects (a lower-level function) than to /identify/ them (a higher-level function) (Fischler & Firschein, 1987). This tradeoff is present in our own eyes, where the color-sensitive central fovea is not very good at detecting contrast, whereas this situation is reversed in the peripheral regions of the retina. Color perception takes place in the most evolutionary developed region of the brain's cortex. Positron Emission Tomography (PET) can measure the varying blood flow to those cortical regions, which correlates with the level of neuronal activity corresponding to the eye's sensation of color. Blood flow to the region of the brain responsible for color vision increases by threefold when subjects first view a picture only in shades of gray, then again in full color (Zeki, 1993). This corresponds exactly to what one would expect from an increase in information due to adding the three color dimensions. Three different types of cone cells are needed in order to perceive color hue or wavelength, and to distinguish color intensity from white (colorless) (Hubel, 1988). Interestingly, the cone cells in the retina responsible for color vision are also responsible for our ability to see fine detail (Hubel, 1988), thus linking color with geometry in our perceptual apparatus. Contrary to what is frequently assumed, therefore, color and linear design are intimately related. This leads us to the final rule. */Rule 8. Color is an indispensable connective element of our environment./* Three arguments support this claim: first, the existence of our highly-developed color sensitivity; second, the neurophysiological coupling between our ability to see detail -- something that is necessary for our survival -- and our ability to see color; third, psychological experiments demonstrating how colors affect us profoundly. Not only does color have the ability to change our mood (with the greater pleasure offered by the more saturated hues); it can also directly affect our physiological state (Mehrabian, 1976). Finding the appropriate color, however, is a very difficult problem, which will not be treated here. A significant portion of the world's economy -- that driven by the advertising and fashion industries -- is based on the connection between human beings and color. Color vision is an essential tool for acquiring knowledge about objects and the physical world. As pointed out by Semir Zeki (1993), consciousness and the acquisition of knowledge are inextricably linked to those neural organizations concerned with color vision. Indeed, he defines a system that can see and experience color as being conscious. Common color-blindness (inherited retinal achromatopsia) is experienced by about 8% of the male population. This is a common though not debilitating condition. People who are color blind lead normal lives, but do have persistent problems in negotiating their world because their color perception is contracted from three color dimensions to two color dimensions. Total loss of color occurs in a pathology known as "cerebral achromatopsia" (Zeki, 1993). Cortical lesions in the specific region of the brain responsible for color vision destroy the ability to see in color, usually as a result of a stroke. Alternatively, transient achromatopsia can be caused by inadequate blood supply to this region. This is an experience well known to jet pilots who fly in high-G aircraft. As a consequence, the world is seen entirely in shades of gray, but the ability to distinguish detail is not affected. Patients who are permanently stricken with this condition describe their surroundings as "drab" and "depressing", and frequently live lives of despair after their injury (Zeki, 1993). Organic objects (such as foods and person's faces) are now repellent. A gray coloration is normally associated with decay and death. These findings are so powerful that I am surprised they are not known by architects. In flat contradiction, we see an infatuation with drab, gray surfaces of raw concrete. Everyone I ask (with the notable exception of some architects) finds such surfaces depressing; and yet architects keep building them. Even worse, they go to great lengths to prevent their users from painting them with color so as to stop the deadening effect. Where paint is allowed to be used, again it is often restricted to depressing shades of gray. This is in stark contrast to vernacular architectures around the world. Owner-built dwellings employ all the color they can find to intensify visual response from wall surfaces. Color appears to satisfy a fundamental human need, as shown by children's art (before they are conditioned to a gray industrial world) and folk art. 8. The value of ornament. Ornament helps to connect us to our environment. In order to satisfy the eight rules given above, buildings ought to either have a continuous swath of high-density visual structure that the eye can follow in traversing their overall form, or focal points of intense detail and contrast arranged in the middle or at the corners of regions. These contrasting elements could include a thick border or edge of the building; a thick boundary around openings and discontinuities; concentrated structure in the centers or corners of walls; etc. (Alexander, 2003). The visually-intense framework should organize information via patterns and symmetries. Color has three distinct functions. First, it can help to define visually-intense regions due to the sensation of color intensity. Second, complementary colors can be used to define contrasting regions. Third, a common color can appear throughout the structure, and help to define an overall coherence. Examples of the above rules comprise most of the architecture from around the world up to the beginning of the twentieth century, including Art Nouveau. Note, however, that key examples of the world's architectural heritage have lost their original bright coloration (it has never been restored because of the stylistic prejudices of today's architects). It is far easier to classify those examples that /violate/ the rules, being the majority of buildings from the twentieth century. Starting from the perspective of well-being, ornament seems a valuable factor in realizing a human architecture (Alexander, 2003; Bloomer, 2000). This paper argues that our neurophysiology requires us to resurrect the ornamental element of architecture that was arbitrarily condemned a century ago. Our conclusion also invalidates a basic assumption of twentieth-century architects: that a building could be conceived in an abstract design space unrelated to human beings. In fact, people actively seek perceptual connection with their physical environment to satisfy a fundamental physiological need (Mikiten /et. al./, 2000). This is consistent with the view of buildings and people forming a unified, interacting system (Alexander, 2003). Buildings do not exist in isolation from nature; the complexity of natural structures establishes a lower threshold value for information. This threshold is part of us. A building is successful or not after it is erected, for many different reasons. In addition to its strictly utilitarian aspects, liking a building depends on establishing visual and tactile connections with it. Ornament is an indispensable part of this connection, but people today, after a century of suppression, have almost forgotten how to generate ornament. Architects who abhor ornament for ideological reasons are quick to point to unsuccessful, visually detracting examples of applied decoration to justify their obsession of eliminating ornament altogether. Since we no longer think about ornament as an integral part of architecture, most ornament created today fails in its task. Ornamentation that does not aim at coherence produces its opposite -- incoherence. Garish or uncoordinated ornament is not satisfying, and could be visually disturbing. Ornament produced within the official design canon of minimalist architecture, however, is ineffective because it does not register. Its detail is too small or indistinct, and its differentiations are too faint or excessively subtle. On the other hand, wherever effective ornamental components are used in contemporary architecture, they are intentionally randomized so as to avoid coherence. This is the fundamental aim of postmodernist design styles (Salingaros, 2000). Successful ornamentation requires the recursive capacity (i.e., the ability to analyze images at different levels, then to synthesize that information) of only the most highly-developed brains, those of human beings. Different types of recursion include rhythm and repetition that generate translational and rotational symmetries; the iteration of structure on smaller and smaller scales that generates fractal patterns; and iteration on the same scale that generates denser and denser connections (Alexander, 2003; Bloomer, 2000). The human capacity for spoken and written language is in fact made possible by our capacity for recursive logical thought. 9. Ornament and writing. Ornament presents organized information that is entirely distinct from text as encoded in letters and signs. Ornament does not communicate a message in written language, but instead in a subconscious language. I will use the example of typography to discuss this difference. When early typeface fonts for printing were cut by hand, they were created with the aim of having maximal legibility, guided by aesthetic considerations. They were serif fonts (in which open lines end with a dot or T-stroke), like present-day Times and Garamond. */Figure 1. Demonstration of how ornament improves a typeface. On the left, the serif letter is the result of highly complex nonlinear operations on the basic design. In the middle, the overly simple sans-serif typeface is neither as attractive nor as legible as the serif typeface. On the right, adding substructure in the wrong places further reduces legibility./* The introduction of radically new typefaces at the beginning of the twentieth century confirms that removing the ornamental serifs also removes a level of meaning. Sans-serif fonts such as Helvetica were popularized along with the modernist Bauhaus design style. They were promoted for their mathematical simplicity. It has been experimentally established that sans-serif fonts degrade legibility. People's reaction to these stripped-down typefaces was strongly negative; so much so that the ancestral sans-serif font was called "grotesque" by the Berthold foundry, which introduced it commercially (the sans-serif typeface Berthold Akzidenz-Grotesk eventually gave rise to Helvetica). The transition from sans-serif to serif fonts shows clearly how ornament works to make form clearer, sharper, hence more distinguishable. Classic serif fonts go much further in establishing a positive emotional connection with the reader. In (Salingaros, 2000) I argue for the necessity of detail from hierarchical arguments. It is not just any added detail that improves the legibility of the font, however. Adding dots or small cross-strokes anywhere other than at the terminals of open lines (and even there, at some arbitrary angle) would degrade the font. Ornament organizes detail in a very precise and sophisticated fashion in order to make a larger form more comprehensible. Adjustments are necessary for a better comprehension of letters. The most effective serif fonts are vastly more complex mathematically than a similar sans-serif font. They show substructure on a hierarchy of decreasing scales. A serif typeface doesn't simply add end-strokes; the entire font is adjusted so that new, more detailed elements cooperate to define a coherent whole. Correcting an old misunderstanding, ornamentation does not superimpose unrelated structure; rather it is a subtle operation that generates highly-organized internal complexity. It therefore has to be extremely precise in order to be effective. 10. Conclusion. This paper reviewed results from neurobiology and experimental psychology, which together provide evidence of an informational connection between people and structures. Visual information input helps to create a physiological state in the user, triggered by the design of the environment. Eight rules were given that facilitate this. The quality of information and its organization affects the emotional connection that human beings establish with forms and surfaces. Traditional architecture uses the interaction between human beings and environmental information to connect people with a building. Detail, differentiations, curvature, and color appear necessary in at least some part of a building, implying that ornament is a valuable component of our environment. Without it, buildings tend to be perceived as having alien qualities. Architects in the twentieth century started to mimic the environments experienced by brain-damaged patients, most certainly without knowing the physiological conditions of eye and brain pathologies that reduce human visual and spatial perception. The architecture of the twentieth century successfully reproduces the spatial experience of persons with eye conditions such as cataract, retinal detachment, and macular degeneration. It also recreates the experience of patients with cortical lesions, who suffer from visual agnosia, cerebral achromatopsia, and other causes of neurophysiological disintegration that destroy the ability to integrate visual information. Architects did this -- and continue to do so -- in the pursuit of design "novelty". *Acknowledgment*. I thank D. Miet and T. M. Mikiten for several helpful suggestions. */References/.* ALEXANDER, C. (2003) /The Phenomenon of Life/, Oxford University Press, New York. [/The Nature of Order, Book One/] BLOOMER, K. (2000) /The Nature of Ornament/, W. W. Norton, New York. FISCHLER, M. A. & FIRSCHEIN, O. (1987) /Intelligence: The Eye, the Brain, and the Computer/, Addison-Wesley, Reading, Massachusetts. HUBEL, D. H. 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Contributions to Architecture