I do not typically unmask a password if it is one I set myself, because I’m familiar with it. However, when I’m typing in an unfamiliar password, particularly if it is very complex (as in your experiment), I unmask after I finish typing, in order to check that I’ve entered it in correctly. This might be when I want to connect to a wifi network, for example, and have to input a pre-determined password.

I believe your experiment might yield different results if you were to provide participants with a simple password, or allow them to choose their own.