This week in social media, Facebook officially announced a caller ID feature for the Messenger app. Meanwhile, one of Twitter's earliest billionaire supporters began criticizing the company, Snapchat invested in a shopping app while preparing for the 2016 election season, and Pinterest unveiled its first "Cinematic pins" -- essentially GIF-like promoted pins that animate as users scroll down.

It's time for Social Media Sunday!

Facebook:

Caller ID for Messenger Rolling Out

We saw the Facebook "Hello" dialer app for Android, which uses Facebook data to identify incoming calls, unveiled just a few weeks ago. Now, it looks like the company is rolling out a similar feature for Messenger in an update for iOS and Android.

Essentially, if you're unfamiliar with a person trying to contact you, the caller ID feature will show a large photo of the person sending the message, along with mutual friends, city of residence and other contextual information. The same will go for friends too, but the utility of the feature rests with identifying less familiar acquaintances and unknown contacts.

Interestingly, Facebook isn't making a big deal out of the new feature that should be rolling out in the U.S. starting at the beginning of the weekend. It was introduced by Facebook's David Marcus in the mobile uploads portion of his Facebook page on Friday. Don't mistake it for an unofficial feature though. Mark Zuckerberg got the first "Like" on the post.

Surprise! Frequent Facebook Posters May Be Narcissistic

Or at least according to a new study by Brunel University in the U.K., via the Independent. Researchers surveyed 555 regular Facebook users and analyzed them to track personality traits, like extroversion, conscientiousness, neuroticism and, of course, narcissism, with their behavior on the network.

The researchers found that extroverts tended to post about social events, while open personalities didn't share personal information, instead using Facebook to post about events or politics. Narcissistic personalities were found to broadcast daily routines, like diet and exercise, in order to "express the personal importance they place on physical appearance."

Take the research with a grain of salt, though, as it was gathered from self-reporting participants, meaning some amount of skew in the results is at least possible, if not likely.

Twitter:

Billionaire Early Backer to Turn Critic

If Twitter didn't have enough critics in the financial world, it can now add one of its earliest boosters to the chorus. Late last week, according to the New York Post, billionaire venture capitalist Chris Sacca took to his blog to voice his opinions on where Twitter has gone wrong, or at least to hype his upcoming blog post where he will share a few "thoughts about Twitter."

Sacca, who was one of Twitter's earliest backers and still one of its largest shareholders, can definitely not be counted as a Twitter hater, even titling his blog post "I bleed aqua," which refers to Twitter's logo color. But he described recently discussing Twitter's shortcoming with CNBC's Jim Cramer as "cathartic" and promised more details to come.

Snapchat:

Job Postings Hint at Big Election 2016 Plans 

Some eagle-eyed journalists at the Guardian caught a job posting from Snapchat recently that hints at the ephemeral messaging service's increasing journalistic ambitions -- and some possible big plans for the 2016 presidential election.

An ad on Greenhouse recruitment asked for "political junkies and news aficionados" with experience in journalism to join a "new content team" at the highly valued startup. This comes after Snapchat snatched CNN's Peter Hamby to head its news division last month, and increasing investment of time and money into its Discover feature, which displays content from media partners.

Pinterest:

Adds 'Cinematic Pins,' Like Facebook's Auto-play Video Ads

Pinterest may be a sleeping giant of a startup, but it's certainly showing it knows how to develop revenue-generating products for advertisers already. This week, according to TechCrunch, Pinterest unveiled the Cinematic Pin -- a promoted pin that animates as users scroll down but stops when you stop scrolling.

The hook? Cinematic Pins only fully play when a user taps on it to full screen. Pinterest devised the promising ad offering after extensive testing with users, who didn't like auto-play ads (trust, dear reader, neither do I) and wanted to be more in control of motion advertisements. In fact, users made that so clear early on, Pinterest never bothered testing standard auto-play video ads.