October 1969

Does the Ability to Visualize Depend on Visual Images?

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 References to these essays must cite them explicitly as unpublished manuscripts.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.

I assume that to visualize a geometrical solid cube is to apprehend its properties (e.g. rectangular dihedral angles) and that to visualize a person's head is to know its features in both full face and profile. Contrariwise, an "image" of a cube or of a face must be a perspective view of it, either a momentary or a frozen picture, and an "image of memory" can only be the trace of a sensation, i.e., of a retinal image. What is "stored" then, can only be a picture, an engram, an impression. But the kind of memory we refer to as visualizing seems to be a knowing of invariants under perspective transformations over time; an awareness of formless invariants. To remember is not to search through the file of snapshots stored in the brain! There is imageless memory just as there is sensationless perception. To "imagine" is not to have an eidetic image, an after image, or a pictorial image, nor is it to represent something to oneself. What is it?