No reason you couldn't do both versions. The blinded part first then at the end ask them their opinions directly. Other psychological studies have done it which is why we know peoples opinions about their perceptions and competency and actions and reasoning and so forth simply aren't reliable. What someone thinks they did or would do compared to what actually happens tends to differ greatly. I argue this is simply because people don't invest enough time into getting to know themselves and their own reasoning.
"The cure for bad information is more information."