I notice my opponent has been cycling through rock, paper, scissors in that order for the first three rounds. If they were to continue this pattern, they would choose rock next. However, given that they've lost three times, they're likely to change strategy. They might anticipate that I'll choose paper to counter their expected rock, and therefore choose scissors. By selecting rock, I can counter this potential scissors play. Additionally, rock has worked well for me in the previous round, so I'll stick with it for now.