Looking at our history so far, there's a possibility my opponent expects me to play paper in this round, thinking I might cycle through options (paper→rock→scissors→paper). If they anticipate paper, they might play scissors, which my rock would beat. While they could also counter my previous scissors play with paper (which would beat my rock), I think there's a higher chance they'll try to predict a pattern in my choices rather than simply countering. Also, since rock worked for me in round 2, returning to a previously successful move might be advantageous.