Understanding Context

Chapter 6. The Elements of the Environment

The earth is not a building but a body.

—WALLACE STEVENS

Invariants

WE’VE LOOKED AT HOW our basic functions of perception and cognition work in an environment and how affordances form that environment. Given that context is largely about how one thing relates to another thing, let’s now look at how we perceive elements and their relationships.

Luckily, our friend James J. Gibson, the ecological psychology theorist, created an elaborate yet straightforward system describing the structures that make environments. We won’t be exploring all its details, but there are some major portions we can borrow for making a sort of building-block kit for purposes of design. These elements start with the most basic: what Gibson calls invariants.

Invariants are persistently stable properties of the environment; they persist as unchanging, in the midst of change.^[112] These are not permanent properties in the scientific sense of permanence.^[113] A hill might erode; a fallen tree might rot; the sun will eventually burn out, but they still involve invariants because they have properties that have been “strikingly constant throughout the whole evolution of animal life.”^[114] Invariance is, then, about the way the animal perceives the environment, not an objective measurement of permanent structure.

The only reason we can do anything is because some parts of our environment are stable and persistent enough to afford our action. The laptop keyboard I’m typing on right ...