ABSTRACT
There is of course one eminent psychologist, the late James Gibson, who has thought otherwise, claiming that in vision, for example, the ambient optical array provides enough information in itself to make it quite unnecessary to make reference to anything that goes on inside the perceiver. There are, however, difficulties about what exactly constitutes a sense. It is at least logically conceivable, that the stimulation of the retina of the eye might result in a given organism in beliefs, whether correct or not, about the immediate environment to the extent that it was optically suited to it, without anything that constituted the experience of seeing. The very possibility of tactual perception of the textures of surfaces is not similarly dependent on the existence of a medium. Whether or not the people think of that as a switching of attention, it does imply that attention must be involved in the ordinary processes of perception.
