receptual

That is to say, this animal, although not yet having begun to use articulate signs, must have advanced far enough in the conventional use of natural signs (a sign with a natural origin in tone and gesture, whether spontaneously or intentionally imitative) to have admitted of a totally free exchange of receptual ideas, such as would be concerned in animal wants and even, perhaps, in the simplest forms of co-operative action.

The Brain and the Voice in Speech and Song 1889

Possibly it may also have been sufficiently intelligent to use a few imitative sounds; and certainly sooner or later the receptual life of this social animal must have advanced far enough to have become comparable with that of an infant of about two years of age.

The Brain and the Voice in Speech and Song 1889

Next I think it probable that the advance of receptual intelligence which would have been occasioned by this advance in sign-making would in turn have led to a development of the latter -- the two thus acting and reacting on each other until the language of tone and gesture became gradually raised to the level of imperfect pantomime, as in children before they begin to use words.

The Brain and the Voice in Speech and Song 1889

Eventually the action and reaction of receptual intelligence and conventional sign-making must have ended in so far developing the former as to have admitted of the breaking up (or articulation) of vocal sounds, as the only direction in which any improvement in vocal sign-making was possible. "

The Brain and the Voice in Speech and Song 1889