I sort of knew before going in to the experiment the "trick" that most humans perceive randomness wrongly. So I knew coin flip sequence "hhhhttthhht" is more "random" than "hthhtththhth", which most people would choose.

I guess my knowledge kind of ruins the experiment. Note I chose the first sequence because I know, but I have to battle with my intuition which urges me to pick the second (wrong) option.