my secret was decidedly less sexy than free will though. i just had XX years of working as a statistician and having a better intuition as to what random strings and numbers actually look like :/
I did have a job where I had to implement a bunch of cognition tests for scientific studies. Initially I worked purely off the research papers describing how the some of the tests work - apparently by presenting a series of random numbers.
After I had the first few up and running, the feedback from the researchers was that my random numbers weren't random enough. "Weird", I thought... I had seeds for their sessions so I could reproduce the sequences they'd seen and they looked pretty random to me.
In the end it turned out my sequences were "too random", they didn't like any number being repeated, having more than 3 instances of the same number within any 6-digit sequence, and a few other "tweaks". Turns out actual randomness is confusing even for some very experienced and well trained people!
Do you have a memorized random string?
It's easy to be random if you have memorized random (or normal) data that your adversary isn't focused on. For example, early digits of pi work in most cases. Or use a generator to create a sequence to memorize.
i have considered trying to memorise some algorithm, but never done it.
i assume that if anyone tried to get me to do these things with a non- uniform distribution I'd probably be screwed, but never tested it.