Looking at the pattern so far, my opponent has played: rock, paper, scissors, paper, rock, paper. There seems to be a preference for paper (3/6 rounds). Since paper beats rock, and I've lost when I played scissors against their rock, I'll choose rock for this round. This is somewhat counter-intuitive, but I suspect they might play scissors this round to break their paper pattern. If they follow their alternating pattern from the last few rounds (paper-rock-paper), they might choose scissors next, making rock a good choice.