Thier surveillance state in 1984 was slightly more advanced than ours, though ours is rapidly catching up. It enabled them to detect deviant, anti-party behavior as soon as it manifested itself. That would trigger increased scrutiny. If it advanced to the point of being displayed in public, the perpetrator would be imprisoned, and eventually killed. Not just killed, but all traces of you would be erased. People would quickly learn not to oppose the ever-changing Big Brother narrative. They were conditioned though fear, and the knowledge they were monitored constantly to intuit wrongthink and stifle such thoughts before they emerged. This is what Ingsoc called "crimestop". People were trained to self-cancel any independent part of their psyche.