SAN FRANCISCO -- Instagram users could soon notice something different in their feeds: Instead of always showing the most recent posts first, the popular mobile photo-sharing app says it will give higher priority to posts that each user is likely to care about most.
If that sounds familiar, it's because that's how Facebook decides what to show users in their News Feeds. Facebook Inc., which owns Instagram, has long used a complex formula to emphasize items it hopes will be "relevant" to each user, based on factors like whether the post came from a close friend or how the user responded to similar posts.
Twitter also adopted a similar approach recently, abandoning its most-recent-first order to present popular tweets from people you follow at the top of your feed.
Not all Instagram fans greeted the news positively. There was almost immediate backlash, which many users posted on rival social media site Twitter.
Until now, Instagram had shown every post in reverse-chronological order, with the newest ones at the top. But as its audience has grown to more than 400 million users, Instagram says it's become harder for users to keep up with the gusher of photos and videos posted by friends, celebrities and other accounts they follow.
"This means you often don't see the posts you might care about the most," the service said in a message to users on Tuesday.
Instagram plans to introduce the new formula gradually, using an algorithm that gives weight to the same kind of factors Facebook considers in its News Feed. Instagram says users will still be able to find all the posts they saw before, although they won't be in the same order.
Judging from posts on Instagram itself, user reaction was mixed, at best.
"It's an Instagram apocalypse," joked CNET's Dan Ackerman. "All these social media brands are trying to find ways to be more engaging, to kind of get you to come back more often and like what you see more. So they're figuring out what posts and what stories and what tweets or photos you want to see, more than just 'here's the 10 last things that anybody posted.'"
The strategy of phasing in the new feature gradually seems intended to avert too strong a backlash from users who don't like the new system -- a problem every social network has faced when it changed familiar features. Facebook annoyed many early users when it changed from reverse-chronological ordering to its current formula several years ago. Twitter has also run into user complaints whenever it hints at changing its layout or the length allowed in tweets.
The change comes as Instagram is also showing more commercial messages. While the new formula doesn't affect advertising, Instagram needs to keep users engaged and interested if it wants to maintain its audience for paid postings.