December 1974
Note on the Norms of Surface Layout
J. J. Gibson, Cornell University
The World Wide Web distribution of James Gibson’s “Purple Perils” is for scholarly use with the understanding that Gibson did not intend them for publication. References to these essays must cite them explicitly as unpublished manuscripts. Copies may be circulated if this statement is included on each copy.
Many psychologists (including the writer) have suggested that certain geometrical norms are very important in visual perception. They are supposed to influence perception by way of memory, for example. It has been suggested that errors in perception, and tendencies over time, are in the direction of a rectilinear world, a rectangular world, and a planar world. There is talk of a “carpentered” world as distinguished from the supposedly “natural” world of curves. But I want to argue here that the tendency to see the world as basically rigid is much more significant. The main invariant of the permanent environment is that it is solid instead of viscous or liquid. The regularity of shape is not so important.
(The invariant of vertical and horizontal is a different matter, not to be confused with either. That depends on gravity).
There are neat norms and dimensions of rectilinear and curvilinear, of flat and concave-convex, of rectangular and acute-obtuse. But a much more important quality of layout is rigidity vs. non-rigidity since rigidity is what makes the environment persist as distinguished from what allows the environment to change.
When we study the phenomenon of “normalization” in perception, or so-called “adaptation”, we should realize that norms of higher order also hold true. The normal forms of Euclid and Plato, the “good” forms of Gestalt theory, are not as basic as we have been led to assume. Straightness of line, planarity of surface, “rightness” of angle, parallelity, and the so-called “regularity” of polygons and polyhedrons take no account of time and change. The fundamental norm on which life depends is rigidity in the layout of surfaces, resistance to deformation.
Rigidity is not as simple mathematically as is rectilinearly, but this does not mean that it is not as basic ecologically. What is complex for theorizing may be simple for the evolution of vision.
This is the lesson of the Innsbruck experiments on spectacle-wearing, it seems to me. Experiments on the aftereffects of prolonged fixation (or inspection) by Gibson, Köhler-Wallach, and others are less revealing. As for the experiments on vision versus touch with spectacles they are wasted effort since the problem is false.