There was of course no way of knowing whether you were being watched at any given moment. How often, or on what system, the Thought Police plugged in on any individual wire was guesswork. It was even conceivable that they watched everybody all the time. But at any rate they could plug in your wire whenever they wanted to. You had to live - did live, from habit that became instinct - in the assumption that every sound you made was overheard, and except in darkness, every movement scruntinized. (Orwell 3).
Telescreens are a good way to brainwash people because the audience is constantly surrounded by the buzz of propaganda. The announcement could be anything the Party wants to say such as, "Attention, comrades! We have glorious news for you. We have won the battle of production!" (Orwell 58). Whether the news is truth or lies, its purpose is to instill national pride into the people. This form of brainwash is control over people's ambitions. The Party wants people to believe that Oceania is the best and most powerful country. They do not want people to believe that there is anything better. The people are made to believe that there is nothing but the Party, the Party cannot be destroyed, or everything is unimportant except the Party. They use the technology that they have for the use of control. .
Another thing that the telescreens control is people's emotions. In the book, O"Brien said that the Party wants civilization to be built on hate. The telescreens instill this emotion in people during the Two Minutes Hate. Two Minutes Hate is a time where the telescreen shows nothing but pictures of foreigners and pictures of Emmanuel Goldstein. Throughout the whole two minutes, people are suppose to take out all of their emotion and turn it into hatred for these people. " The program of the Two Minutes Hate varied from day to day, but there was none in which Goldstein was not the principal figure.