I think that people form biases because we all have our own opinions and ideas about others opinion and ideas. We all want things to be right. No one ever wants things to not be how they want it to be, and so that's how biases are formed. Sometimes bias can change or reflect on our own thinking.
For instence, movie critics say bad things about movies and actors/actresses all the time and so that way people will listen to what they say and sometimes think it's true because they know nothing about what the movie critics are saying, or they just believe everything that they say. Sometimes people may disagree and that creates biases also.
How does bias appear in the media?
In the media, just like the movie critics, can also change others thoughts about a certain subject. Stereotypes are also very big on bias; if someone says that all Mexicans are immagrants then someone else may stick up and and say something, and they all might have disagreements and create bias. If someone says all asians eat dogs and cats, then others might disagree and bias will form again.
The media has all sorts of biases and it only depends if people agree with what they say or not, if they do then that's great, but if they don't then there will be arguments and biases form again.
How can you tell when someone is presenting an opinion as fact?
You can tell whether someone is stating an opnion as a fact is when they state what they think and say it's a fact, or if you already know what the subject that they're talking about is then it's absolutely an opinion from their thoughts. A fact isn't always a fact unless you already know what the true meaning of it. Usually people in the media try to portray their opinion into facts, especially on celebreties and famous people, maybe because they don't like a certain subject or they just want people to agree with them.
How do our own biases affect our understanding when we read?Biases can affect us by trying to make us believe what is being said or told. It can also affect our reading because if all is not true then we'll all get the wrong message of the reading.
Sometimes when I read I disagree on somethings that I might not agree with. If you know that something that's been said is wrong then it's best to create biases.