I'm choosing rock because my opponent may anticipate me continuing my winning pattern and choose scissors to counter what they might think would be my paper play. Since I won with rock in the previous round, the opponent might expect me to switch to paper following the logical progression of the game. By sticking with rock instead, I may surprise them if they choose scissors to counter my expected paper. Additionally, rock has been successful for me in the last round, so there's strategic value in repeating a winning move occasionally.