(1) discrimination: identification of forms;
(2) memory: ability to remember single forms individually;
(3) spatial relations: determination of the correct direction of forms;
(4) form constancy: recognition of the same form when it varies in size from the stimulus;
(5) sequential memory: ability to remember a number of forms in a series;
(6) figure ground: finding a form when it is hidden among other forms;
(7) closure: determination of a whole form from parts of this form.