Instagram is hiding the number of likes on posts in seven countries to "remove pressure" on users.
The trial began on Thursday in Australia, Brazil, Ireland, Italy, Japan and New Zealand, Instagram said in a statement.
It was launched in Canada earlier this year.
The social media platform said in a statement to users: "We want your friends to focus on the photos and videos you share, not how many likes they get.
"You can still see your own likes by tapping on the list of people who've liked it, but your friends will not be able to see how many likes your post has received.
"We're looking forward to learning more about how this change might benefit everyone's experience on Instagram."
Users will see only a user name "and others" below their posts, where they previously saw the number of people who had liked it.
Mia Garlick, Facebook Australia and New Zealand director of policy, said in a statement that the goal was for users to feel less judged.
"We hope this test will remove the pressure of how many likes a post will receive, so you can focus on sharing the things you love," she said.
The moves comes after some studies linked social media platforms to mental health difficulties for young people.