In contrast to the mathematical concept of space as presented on maps, plans, etc. “hodological space” is based on the factual topological, physical, social, and psychological conditions a person is faced with on the way from point A to point B…
Space can be thought of in two fundamentally different ways: From one perspective, it consists of so many physical objects arrayed outside the humans experiencing it. From the contrasting perspective, the one we are about to consider, space is something that matters only insofar as a human reacts to it. We regularly use this subjective outlook when we say we are going forward or sideways or when we refer to objects being beyond one another.
The German psychologist Kurt Lewin (1890-1947), well known for his role in the development of Gestalt psychology, proposed such a person-centered theory. He also elaborated a psychological field theory of human behavior—that is, a framework for understanding the forces that prompt us to act as we do.
Interestingly, he was also the person who invented the term hodology for the study of paths. I am considering here his general spatial theory specifically as it relates to walkers and walking, for which it is well suited.
Lewin began with the notion of a person’s life space, consisting of the aggregate of “all that is personally meaningful or significant in the external environment (such as other people, possessions, the weather, and a garden) and in the mind (such as needs, goals, thoughts, and beliefs).”
For Lewin, life space involves three spheres of behavior—mental, social, and physical. Yet even in the physical sphere, the focus is not on external objects but on how the individual conceives of them. A tree becomes relevant in field theory only when a passerby thinks about it, looks at it, or is prompted to approach or avoid it. In this understanding of space, a tree that falls in the forest hasn’t fallen until someone reacts to its new position.
Objects are important precisely for the opportunities for interaction that they afford to humans. A brick walk, for instance, affords support for standing or walking, continuity for going somewhere, and colors and patterns for looking at. So a landscape and its components can be assessed in terms of their affordances, or the opportunities they offer for experience or action. Affordances are invariant, but people’s reactions to them are not. A path always affords the opportunity to move along it, but some people sometimes refuse to walk on it.
Lewin called a goal’s subjective attraction a valence, a word commonly used in chemistry and the biological sciences to mean the same thing: the power of attraction that exists between two objects. In Lewin’s scheme, valences apply between a human and something else.
Lewin assigned positive valences to attractive destinations, higher valences for greater attractions, and negative valences to unpleasant, dangerous, repulsive landscape features or places. For a thirsty person, a desert’s valence is negative; a distant oasis’s is positive; and a nearby waterhole’s, highly positive.
This dovetails neatly with Maslow’s hierarchy of needs, where more primal needs generate higher valences than lesser needs.
Valences and goals arise out of humans and our needs, not from landscape objects themselves. A steep path up to an overlook is attractive for those seeking challenging recreation, valueless to the hungry, and repulsive to acrophobics.
A valence generates a psychological impulse with magnitude and direction toward or away from a place. It can thus be depicted as a vector, an arrow with a direction and a length corresponding to its attractive or repulsive strength.
It is no coincidence that one form of wayfinding and one way to characterize a path is vectorial, that is, going a certain distance in a certain direction. So taking into account the attractive power of landscape features on humans is intimately connected with creating and using paths.
The power of need-generated valences does not act alone; it is tempered by mental barriers and the wishes of others, which Lewin called induced forces. We may refuse to cross a desert because of the distance, the risk of thirst, the fear of scorpions, or the doubts of others.
Still, real, physical obstacles can be considered induced forces with negative valences. In fact, there is evidence that humans react to obstacles as though they are imbued with repellent forces that vary according to field theory: experiments show we are more repelled the more directly we are heading toward obstacles and the wider they appear to us to be.
The psychological force resulting from the sum of valences, barriers, and induced forces prompts locomotion, movement in each of the three spheres—mental movement as a change in thought, social movement as an altered relationship to others, or physical movement as a perceived advance of the human body through space.
Applying even a small number of Lewin’s constructs to walking and paths highlights their potential usefulness to landscape design. When the strength of locomoting forces and psychological barriers toward a given goal among potential path users is even approximately understood, then a realistic appraisal can be made of the needed location, size, and nature of a path to get them there. Without a sense of these mental, social, and physical forces at play on a site, path design can be little more than a shot in the dark.