Since my opponent won with scissors in round 1, there's a reasonable chance they might stick with scissors again (players often repeat successful moves). Additionally, after seeing me play paper in round 1, they might anticipate I'll switch to scissors to counter their previous move, which could lead them to play rock. In that case, we would tie. Overall, playing rock gives me a good chance to either win (if they repeat scissors) or tie (if they switch to rock).