(5) The memory image and the perceptual image may not be coördinated with the movements in drawing. This capacity is innate.
(6) The sight of the drawing in its imperfection as compared with the memory image may disturb the image.
(7) The drawer may lack schemata on which to found his drawing.
(8) There may be failure to comprehend how one may project space in three dimensions upon a plane.
(9) Manual skill may fail.
(10) There may be no artistic sense.
(11) Inability to draw may arise from a combination of various of these deficiencies.
Manuel has offered the following analysis, after study of persons especially talented:
The following characteristics, each an independent or partially independent variable, seem closely related to ability in drawing:
(1) The ability mentally to note a visual form, and, by certain lines and areas, to reproduce it or significant features of it.