Thank you for participating in this experiment! You will be looking at stimuli 
rendered in 3d on our computer display and making judgments about the lightness 
of certain square target patches. You can think of "lightness" as "what color paint the 
patch is coated with". 
 
On each trial, you will see two squares ("contexts"), each consisting of a random 
assortment of grayscale rectangles. These two contexts are at a right angle to each 
other. You will also see two squares near the center of the display. The two squares 
will always be oriented as follows: one will lie flat against one of contexts, and the 
other will sit in front of the same context, but be rotated such that it lies in the same 
plane as the other context. 
 
Your task is to simply indicate which of the two squares looks lighter. If you think 
the square on the left looks lighter, press the left shoulder button on the controller; 
if you think the square on the right looks lighter, press the right shoulder button on 
the controller.  
 
There are a total of 800 trials. Though this seems like a large number, each trial 
takes at most a second or two. In addition, there is no time limit, so please feel free 
to take a break whenever you feel like it. There is no need to tire your eyes out; in 
fact, that would be detrimental to the experiment! 
 
If you have any questions at any point, please feel free to stop and get the 
experimenter. There is no time limit, so please try to make the most accurate match 
you can. 
 
Thanks!