Why We Hug the Edge of Open Spaces

The tenth and final installment of the Biophilia and Healing Environments series examines how human biology dictates the design of the physical settings we inhabit.

The portico of San Luca, Bologna, Italy, built 1674-1793. This 4 kilometer-long structure consisting of 666 arches has but a single purpose: to define a sheltered path to the Church of San Luca on the hill.

Drawing by Nikos Salingaros

Human biology, an artifact of our evolution, dictates much of how we behave, and offers the key to how space is actually used. Interactions with the built environment determine our behavior, often in surprising and mysterious ways. For example, people tend to avoid exposed open space and prefer to walk along its protected edges or perimeter boundaries (Salingaros, 2005: pages 32-33). Ann Sussman and Justin Hollander (2015) discuss the mechanism of thigmotaxis, defined as how organisms move in response to edge conditions: research finds that not just humans today but primitive microscopic organisms going back in evolutionary times also tend to avoid open spaces and stick to protected edges. For the human brain, the edges not only help us feel safe, they help us efficiently orient and create a “mental map” of our surroundings.

Our sensory system evaluates every physical setting we inhabit, however briefly. Our neural computations do not present us with a quantitative answer, of course, but instead we get an unmistakable feeling in our body reacting to hormones and nerve signals. Our body’s intuitive response tells us whether the immediate environment is safe or not. The human perceptive system is exquisitely designed to detect variations in the quality of our surroundings. We adapt our behavior accordingly. A spatial configuration, translated subconsciously but very rapidly into an intuitive assessment of where we are, can be evaluated only in person, directly, using one’s senses — all of them. That is why, ultimately, our perceptual system is the only qualified and dependable judge of where we are and whether it is good for us. Such judgments cannot easily be made from pictures, architectural drawings, intellectual arguments, or others’ opinions.

Almost all architects have been taught to think of space as fixed and static, whereas human movement and life always generate a dynamic interaction with our environment as we move through it. Life couples us to the structures we inhabit, our perception engaging an information field that shifts continuously as we move. Dynamic interaction determines the effect that the environment exerts on us as we move about, and these complex signals are static only when we are stationary. Adaptive design takes into account our visceral responses as a result of movement — the dynamic versus the static nature of information, which are entirely different.

The architectural experience of paths, for example, can be explained by understanding “dynamic biophilia”. Wayfinding, whether inside or outside, depends on our assessment of environmental information changing as we move about. Markers and signals help us navigate a space by continuously reinforcing our perception of how we are expected to flow through it, or, conversely, such signals, if poorly designed, hinder our movement with psychologically confusing cues (Lyons Stewart, 2015). Much directional and navigational information resides in visual patterns on the ground. These engage us and draw us to move forward, and keep us on the path. Studies performed in hospitals of where people unconsciously walk demonstrate how floor color and pattern direct circulation. On the other hand, some current design practices ignore or contradict natural pedestrian flow.

We respond intuitively to the information patterns of floors (Salingaros, 2006: Chapter 7). Visual floor patterns strongly influence the direction in which we move and the ease with which we move. Unfortunately, many floor surfaces are too plain visually to help guide circulation and movement. Even worse, we encounter patterned flooring that gives cues contradictory to the intended movement through a passage, and those subconscious signals confuse us and cause psychological stress. Debilitating consequences to patients can attend cognitively jarring floor patterns in hospitals, daycare centers, schools, and housing for the elderly (Lyons Stewart, 2015). Poorly designed floors burden walkers everywhere, but confusing hospital floors surely are to blame for the most painful and unnecessary awkwardness.

In conventional architectural practice, paths in buildings and other built spaces tend to be designed as abstractions. Artistic intent expressed on a plan too often trumps utility and human nature. That approach ignores both biophilia and the dynamics of human interaction with structures. People get lost because the architect or interior designer did not apply adaptive design to direct movement efficiently (Lyons Stewart, 2015). We frequently get ambiguous or even contradictory signals from the built environment as we move. The paths by which we navigate spaces can be disturbing — often generating the sensation that we would rather walk elsewhere but are thwarted by obstacles, either signs denying passage or structures blocking passage. We are biological creatures, after all, and respond subconsciously far more than we realize to the world around us.


Table. Alexandrine patterns that determine paths (with my own summaries).

Pattern 98. Navigation must be intuitive and effortless. It helps to have an obvious sequence of flows, a correct positioning of paths, and appropriate supporting structures. 

Pattern 114. Satisfy the feeling of having one’s back protected by a solid structure (refuge), while being able to see out to the world (prospect). 

Pattern 120. A path is composed of a sequence of intermediate destinations. Flow is governed by the body’s instinctive movements and psychological reactions. 

Pattern 121. A successful path is also a welcoming space for people to linger in if they are not in a hurry. 

Pattern 132. Make indoor transition corridors short and visually interesting. Use natural light, and design corridors in the same way as the building’s living space. 


A Pattern Language (Alexander et al., 1977) presents design tools for indoor and outdoor paths that pay attention to human sensibilities. [For a background discussion on patterns, see Leitner (2015)]. The following five living patterns provide the elements for a design template: Pattern 98, “Circulation Realms”; Pattern 114, “Hierarchy of Open Space”; Pattern 120, “Paths and Goals”; Pattern 121, “Path Shape”; Pattern 132, “Short Passages”. In particular, Pattern 114, “Hierarchy of Open Space”, anticipates and contains two notions later used by writers on biophilia: “refuge” is a psychologically safe space where we feel free from threat, whereas “prospect” means the ease of seeing locations some distance away that might attract us if we perceive obvious biophilic properties there (Browning et al., 2014; Kellert et al., 2008).

The paved path winding around the Acropolis Hill in Athens, Greece. Designed and built by Dimitris Pikionis, 1957.

Drawing by Nikos Salingaros

Results from neurophysiology, living patterns, and biophilia reinforce and tie together concepts necessary for the design of paths. These fruits of our evolutionary development from human ancestral environments are arguably shared by primitive life forms that move about even to this day. Applying these design notions to paths, every portion of the spatial environment along a path must offer refuge so that a person feels safe and comfortable while negotiating that journey. At the same time, a prospect offers us a range of goals for our journey, if we choose to leave our refuge and move toward them. An intelligently designed path will, in theory, reduce our instinctive resistance to doing so.

If it is to contribute to a sustainable future for humanity, innovative architecture must foster the greatest possible number of psychologically nourishing interactions. Systemic harmony, organized complexity, and coherence in our surroundings are based on human neurophysiology, not abstract imagery (Alexander et al., 1977; Browning et al., 2014; Kellert et al., 2008; Salingaros, 2005; 2006). Because adaptive design works with rather than against nature and climate, its energy expenditures are more sustainable. But healing environments are intrinsically sustainable more because they are loved viscerally — as our favorite historical rooms, buildings, and urban spaces are loved — by everyone who experiences them. They need not make “statements” to assert their “relevance”. People want to preserve healing environments because they are nourished by them.


Christopher Alexander, S. Ishikawa, M. Silverstein, M. Jacobson, I. Fiksdahl-King & S. Angel (1977) A Pattern Language, Oxford University Press, New York.

William Browning, Catherine Ryan & Joseph Clancy (2014) “14 Patterns of Biophilic Design”, Terrapin Bright Green, New York.

Stephen R. Kellert, Judith Heerwagen & Martin Mador, Editors (2008) Biophilic Design: The Theory, Science and Practice of Bringing Buildings to Life, John Wiley, New York.

Helmut Leitner (2015) Pattern Theory, CreateSpace, Amazon.

Barbara Lyons Stewart (2015) Flooring Psych, Architectural Design Psychology Press, San Anselmo, California.

Nikos A. Salingaros (2005) Principles of Urban Structure, Techne Press, Amsterdam, Holland; reprinted 2014, Sustasis Press, Portland, Oregon and Vajra Books, Kathmandu, Nepal.

Nikos A. Salingaros (2006) A Theory of Architecture, Umbau-Verlag, Solingen, Germany; reprinted 2014, Sustasis Press, Portland, Oregon and Vajra Books, Kathmandu, Nepal. Chapter 7 “Pavements as Embodiments of Meaning for a Fractal Mind” (co-authored with Terry M. Mikiten and Hing-Sing Yu) first appeared in Nexus Network Journal, Volume 2 (2000), pages 61-72.

Ann Sussman & Justin B. Hollander (2015) Cognitive Architecture, Routledge, New York.

Recent Viewpoints