I think I have a way to test someone's pride level. That is by their reaction through optical illusions. Works on anybody.
It's not about how we are fooled or not fooled by those illusions, but how we react towards them. The ones who find any of these illusions intriguing despite being fooled, curious about them, are the most humble ones, and the reverse is true for the proud ones. The proud ones will get frustrated and even angry.
A quick google search on "optical illusions" provide plenty of samples.