Wouldn't a better prompt be something like > Click the button to roll the die > (plausible dice roll animation is played) > Try to guess the result > (buttons labeled 1-6) That way there's no confusion about how to interpret the instructions, it's just people trying to predict the results of an event they perceive to be random and fair. When it asked me to create a "good" outcome, I didn't really know what it was exp…
However, I approached the exercise in the same way as you did, as an adversarial game. I tried to generate numbers that would trick a human who is tasked with filtering out the series as random. No results repeating stuck me as a tell that the series was done by a human, so I included a fair number of repetitions of the same result that's still statistically plausible. Not sure how to work around that in the instructions.
Edit: I think the study might say more about what the player thinks about other's expectation of randomness than about the player's own understanding of randomness.