Tips and Tricks
The Lang Pencil Test
Very easy: take a pencil in each hand. Hold them about 30 centimeters apart, and then
move them towards eachother such that the tips touch. If you are unable to do this you
don't have full stereopis. In all likelyhood random dot stereograms are no fun for you.
Tip: when a non- strabismic person wants to do this, tell them they have to close one eye
Poor Men's Bagolini Striated Lenses Test
With an old pair of (sun)glasses and a bit of vaseline one can emulate the Bagolini Striated Lenses Test at low cost. Streak each lens with some grease and wipe it such it yields a striated pattern from down-left to upper-right on the left glass and from upper-left to down-right on the right glass (or the reverse of course).
You'll need that penlight again - penlights are mighty popular with MD's and those
practicing kitchen science. Put the glasses on and look at the penlight. Do you see one or
two lines of light crossing the penlight? Or is a piece of one of the lines missing in the
The Red Glass Test
Actually, green works just as well. It doens't have to be glass either - a transparent candy wrapper does the trick too. You'll also need a penlight. Look at the light from a distance of a couple of meters. Just one penlight there. Now hold the red glass in front of the eye you use the least (probably the one you know as the "lazy" one). Chances are you now see two lights - one white and one red.