Meet Gabriela. She is in her forties, Latina, and lives in Miami. She’s not very interested in politics, but she cares about the economy – and abortion rights. And she doesn’t know if she will vote – or for whom. The only problem? She’s not real.

Gabriela is one of five fictional characters I created in 2022 to track how different people, with different political views, are targeted by social media content. It is part of an ongoing experiment for the BBC America Podcaststudying how social media algorithms can influence how people vote.

As election day approaches, it is the undecided and disillusioned voters that the two main presidential candidates are trying to convince as a last resort. How is the battle going on their various social media feeds?

While some of these “illegal voters,” as we call them, were created to represent a certain political viewpoint based on Pew Research Center data, Gabriela started out by expressing essentially no interest in politics on his social networks. But over the past two years, her feeds have evolved as I’ve watched and followed the content she recommended.

How to create an undercover voter? First, I created his profiles on major social media sites – X, TikTok, Instagram, Facebook and YouTube. I kept her account private and, since she wasn’t political, I had her follow and interact with content that had nothing to do with politics: coupon pages, dance videos, community groups and other content in Spanish.

All five characters have private accounts and no friends.

These social media profiles can’t offer a comprehensive view of what each voter is pushing online, but they can provide insight into the impact of social media sites in this election.

Every time I was recommended content on one of the platforms, I took an interest in it – whether it was watching the latest TikTok dance or following a Facebook page about saving at the supermarket – to see what the algorithms would then recommend to Gabriela.

Soon, political content was also recommended to him.

Now a war is raging in her feeds between Donald Trump and Kamala Harris — and who seems to have the upper hand is different depending on which social media site she visits.

Gabriela’s feed on

One popular meme, for example, featured four images from Trump’s campaign, from his mugshot to his recent photoshoot in a garbage truck. Next to the photos are maps of the United States showing states going red for Republicans.

“That seems accurate,” the cation read. The message was clear: Trump is making a comeback.

Content created and shared by very active Trump supporters on X has tens of millions of views. While there are also groups of accounts supporting Harris, they don’t appear as often in Gabriela’s feed. Articles about Trump also tended to focus on him as a person: When politics came up, it was usually immigration or the economy.

A major change happened at X after Gabriela’s profile was created in August 2022: Elon Musk bought the social media company. Since his takeover of Twitter in October 2022, Mr. Musk has made a number of changes, ranging from renaming it X to offering a paid premium service.

Changes have also been made to the algorithm, affecting which types of content get the most popularity.

Now, almost every time I open Gabriela’s thread on X, I see a post from Mr. Musk himself near the top. He has repeatedly posted his support for Trump, and in recent days he has re-shared some unfounded claims of election fraud. This is very different from what her feed looked like when she first created her account.

A recent post that Mr. Musk re-shared, in which his profile had been recommended, spread unfounded rumors that Colorado election officials may be complicit in voter fraud.

The message shared by Mr. Musk referred to an employee error exposing passwords to some election equipment.

However, according to state officials, “the vote counting equipment requires two passwords to access it, and those passwords are kept separately,” which they say means “the election system remains completely secure” following the error.

I spent time this summer with election officials at a vote-counting center in Jefferson County, Colorado.

A computer scientist called Cuong told me how, since 2020, he and his colleagues have repeatedly been “targeted by harassment, accusations that we are doing nefarious things”, triggered by unfounded claims of – for example – machines to vote hacked or broken.

Gabriela’s feed on TikTok, on the other hand, frequently recommends montages of Kamala Harris, often speaking at rallies. These are created by supporters and are similar to the types of posts users create to support their favorite celebrity or musician.

It reads “America is ready for Kamala Harris” on an account called Latinos for Harris.

The clips tend to focus on Harris as a person rather than her policies – although several reference the topic of abortion rights and the issue of personal liberty.

When a comedian at Donald Trump’s Madison Square Garden rally called Puerto Rico a “floating island of garbage,” it sparked backlash from many in the Latino community.

Gabriela’s TikTok feed has featured video clips of this moment, or comments about this moment, often with Spanish captions offending these comments.

The algorithm served up content that was highly relevant to Gabriela’s identity as a Latino voter.

His feed also contains content from official accounts belonging to the Donald Trump and Kamala Harris campaigns.

A campaign video shows Harris alongside Michelle Obama in front of an American flag declaring this election “is going to be close,” with 7.7 million views.

Another shows Donald Trump dancing alongside popular streamer Adin Ross. This has been viewed 67.1 million times, which shows how its content has a huge reach, even though it’s not featured so much in Gabriela’s feed.

While TikTok bans political ads, the same is not true on YouTube, where Gabriela has been targeted by several of the two main candidates. The paid ads it receives tend to focus on economics. A video from Harris’ campaign team claiming she will “cut taxes for 100 million working Americans.” Another ad from Trump’s team declares “there’s no time to waste! Make a plan, go to the polls and vote for Trump.”

Much of this content, whether ads or messages from campaigns and supporters, appears to be aimed at motivating people to vote, rather than changing their minds on an issue.

Like her TikTok feed, Gabriela’s YouTube skews toward partisan political content, opinions, and campaign messages. But I haven’t seen the same type of posts pushing unsubstantiated claims of voter fraud that I spotted on Gabriela’s X feed. His X-feed was overtaken by almost entirely political posts.

His Instagram and Facebook accounts have remained fairly apolitical. Meta, which owns both social media companies, decided to stop recommending political content from accounts that users don’t already follow earlier this year.

The biggest changes I’ve spotted on Gabriela’s social media in the two years I’ve been managing her profile have happened on X.

In recent weeks, Mr. Musk has been very vocal about his support for Trump, something he has the right to do as a private citizen. He also accused Twitter, as well as other social media sites, of suppressing right-wing viewpoints. And he’s already said he thinks X is a space for all political views.

But Gabriela’s thread shows how, at least to an initially neutral viewer, the site has tilted in favor of Trump – which appears to be partly due to changes made to the way the site operates during Mr. Musk’s tenure.

Last month,

I studied how these changes helped some users earn thousands of dollarsthey say, sharing content including election misinformation, AI-generated images and unfounded conspiracy theories.

X’s user base is smaller than many other sites. But it’s the home of politicians, activists and journalists and screenshots from its site may migrate to larger platforms.

Another big but less extreme change happened on Gabriela’s TikTok feed.

Before, she didn’t see much of Democrats, but after Joe Biden announced he was no longer running for president, her feed was increasingly flooded with pro-Kamala Harris videos.

Because Gabriela isn’t real, it’s impossible to know how much she would react to one of these social media posts. Many factors other than the online world could influence his decision.

One thing is for sure, though, my previously apolitical constituent hasn’t been able to avoid the deluge of politics — and the sites’ algorithms, which seem to favor engagement above all else, shape the way she receives politics through her flow. Who and how she votes might depend on which social media site she trusts and relies on.

X did not respond to questions from the BBC. X claims online that its priority is to protect and defend the user’s voice. Every other major social media company says it has policies and measures in place to protect users from misinformation and hate.