The 32-year-old pop beauty admits she used to spend hours reading her followers' comments about her appearance and clothes on social media, but over time she developed a carefree attitude towards other people's opinions and she only listens to her closest friends now.
She said: "I've given up on what people think about me.
"I have a great group of people around me that I listen to and value their opinions.
"I gave up scrolling down on the comments. Fashion is a way to express yourself.
"We can say we're funny or romantic or serious or sarcastic just by how we display ourselves."
When the 'Chained to the Rhythm' hitmaker - who is dating Orlando Bloom - first moved to Hollywood she was obsessed with thrift shopping and picking out quirky items as she loves her outfits to be an expression of her personality.
She told PEOPLE magazine: "When I first got to Los Angles, I cultivated my style on a budget, always shopping at thrift stores or vintage stores.
"Once I found these flats that looked like Dalmatian dogs.
"They had ears that moved and a tongue that stuck out.
"They were such a conversation piece
"That's what is so great about fashion. It's a form of communication.
"You don't have to start a smoking habit to start talking to someone. You can just wear cool shoes. It's an icebreaker."