Here are the techniques for stripping away meaning that I mentioned in that post:
Negative space. This refers to the space around and between objects. Many artists train themselves concentrate on this space so that they can see the shapes of the objects inside it more accurately. Here are some short articles about it: "Figure/Ground Relationship" by Alice Taylor; "See Like an Artist: negative space" by Jay Alders; "art stuff - negative space and the left brain" by Kathy Hebert; and "Hand Drawing Demo #6: Reviewing Left Brain/Right Brain" by Anne Bobroff-Hajal.
Inversion. There are drawing exercises in which one copies inverted images in order to focus attention on shape. Here are two typical articles about this: "Upside down Drawing and Contour Drawing" by "Davy"; and "Day #031 - Drawing Picasso’s Igor Stravinsky Upside Down" by "Neelima". It occurred to me that psychologists have used inverting spectacles in experiments on the adaptability of vision. Could they help us draw? It should be possible to program image inversion into Google Glass.
Blind drawing. This is drawing without looking at the paper. Some artists use it to improve hand-eye coordination, or to make themselves aware of what's actually seen rather than some symbolic stereotype for it — i.e. to strip away meaning once more. The following articles explain these: "Blind Contour Drawing: A Classic Drawing Exercise" by Helen South; and "Blind Contour Drawing: Drawing by Touch" by Carol Rosinski; and "If You Don’t Begin Blind Contour Drawing Now, You’ll Hate Yourself Later.". By the way, the third article refers to Kimon Nicolaïdes, whose book The Natural Way to Draw advocated blind drawing.
Cold water in the ear. A strange idea, but one mentioned in the paper "Spatial- and verbal-memory improvement by cold-water caloric stimulation in healthy subjects", by D.Bächtold, T.Baumann, P.S.Sándor, M.Kritos, M.Regard, and P.Brugger. The authors say that putting cold water in subjects' left ear sped up their recall of object locations, while water in the right ear sped up recognition of words. They suggest that the stimulation activates structures in the opposite hemisphere, speeding up cognitive processes there. But it seems this is not likely to be useful. Glyn told me that the effect is too short-lived to be any use. It also causes nystagmus.
Transcranial stimulation. I posted about this in "Trans-Cranial Magnetic Stimulation and the Curled-Cat and Bristly-Scottie Drawings of Allan Snyder's Subjects". Snyder applied strong magnetic fields to his subjects' brains, to test the hypothesis that the extraordinary skills shown by savants could be induced in normal people by simulating the savants' brain impairments. Drawings done under TMS are shown on page 4 of the research paper. It seems to me that the cats and dogs drawn under TMS by subjects "N.R." and "A.J." are less naïve, artistically speaking, than those drawn normally, and that the effect is big enough to be worth investigating further. Glyn also thought it worth following up.