We all see the world through different eyes. Each experience made is different for each person. People grow up differently, culture, religion, parental guidance, the sway of peer pressure, nationality, ethnicity, race.... The same is for the characters we create for our books. Perception can affect behavior, make people behave in ways they don't even understand. Perception creates perspective.
When creating characters I think it's important to know where their perceptions stem from. You don't have to explain it to your reader, but you can show it in their behavior, the way they respond to other characters, to challenges. As a writer if you know a character, who could be a supporting character or a main, grew up with an abusive parent, they might perceive violence differently than someone who grew up in a loving family. Your character's perception can define the way they look at the conflict, how they decide they want to overcome it.
Perception can create tone in characters, in their voices, their body language. It can manipulate the way they order a meal, a glass of wine.
This reminds me of a friend of mine. She's always enjoyed wine, but within the last few years I noticed she's been drinking more of it, as if it distinguishes her more than her usual Jack. Anyways, she went through a phase where she drank Lambrusco, a sweet red wine that's about $7 a bottle. She enjoyed it, even ordered it at restaurants. Then a year ago she got a job at a winery. The owner imports all his grapes from France. He makes several different kinds of wine, shares his expensive collection with friends and colleagues. She learned much about wine, it's process, the culture of it. I have to smile at this. A few months ago I made a statement that a nice bottle Lambrusco sounded good. She shot me an almost disgusted look and said, "We've got to teach you about wine."