In the US, advertising as we know it now has existed since the colonial era — but, according to advertising historians, sexuality didn't become a major part of US advertising until around the 1850s. "The origins of sexual appeal in US advertising," write John McDonough and Karen Egolf in The Advertising Age, "can be traced to medicinal products advertised before the Civil War. These ads featured wooden engravings of women's faces, often the only illustration on the page, to attract the reader's attention." While this seems tame to us now, sexualized ads developed in step with the culture's sexual mores — it took a long time for sexual appeals to make it into ads to begin with, and McDonough and Egolf note, ads in the 1890s that featured women's ankles were considered provocative.

France raised the bar for sexy ads in the late 1800s, with beautiful advertisements for burlesques, dances and music halls painted by artists like Jules Chéret, full of voluptuous women inviting you to have a good time. And, as advertising historian Tom Reichert notes, among the first-ever "collectible cards" were erotic picture cards of women found in packs of Duke's cigarettes in the 1880s (you could collect the whole set with enough purchases). But in the US, the jump from hidden erotic cards to more overt sexual female bodies happened in the early 20th century, with advertisements like those for Woodbury's Soap, which paired slogans like "A Skin You Love To Touch" with images of women being fondled romantically by men.

In the decades since, eroticized women have become commonplace in ads; similarly eroticized men wouldn't really enter the advertising scene until the late-20th century, and still only make up a small portion of ads (in 2003, 22 percent of ads featured sexualized women, while sexualized men only turned up in 6 percent of ads).

But while ads with sexual content are common today, they're not necessarily seen as a positive social force. In addition to being thought to negatively impact women's body images, they've also been accused of encouraging heterosexual men to objectify women, and a number of sexy ads have also been criticized for racism — whether due to engaging in racist stereotyping and insensitivity, such as a 2015 Carl's Jr ad that depicted bikini-clad women playing volleyball around a "border wall" dividing the US and Mexico, or for portraying white women as the default for "sexiness."

Considering what a charged and complex relationship the American public has with sexy ads, you'd think they'd at least do a great job at making consumers buy things. But in reality, their influence isn't so major.

One reason is that sexualized ads almost exclusively target a very specific demographic: heterosexual men. Wirtz's study found that men in general felt positively towards the sexualized ads, while women tended to view them more negatively; past research has indicated that heterosexual men responded positively to advertising that featured highly erotically charged images of couples, while heterosexual women tended to respond more positively to more mildly erotic images. Considering that women drive around 80 percent of consumer purchases, ads that specifically court men in a way that many women find unappealing won't necessarily drive sales in a big way.

But even among heterosexual men, sexy ads don't always accomplish what they're supposed to. Researchers in 2015 examined 53 different studies and found that men were actually less likely to be able to remember the specific brand being advertised in a sexy advertisement.

And, of course, even when men enjoyed the sexualized ads, they didn't necessarily decide to buy the things advertised in them.

While we may assume that sexualized ads don't work if they don't directly influence someone to make a purchase, experts tell us it's actually a more complicated situation.

Dr. Melissa Burnett, professor of marketing at Missouri State University, notes that whether an ad contains sexualized images or not is far from the only reason an ad might be succeeding or failing. "In many cases, the use of a sexual appeal could simply not be appropriate [for the product being sold]," Dr. Burnett tells Bustle. "However, even in situations that would suggest a sexual appeal would be an effective strategy, the message may not be on target, poorly concepted or executed, or delivered at the wrong time or place."

Beth Egan, Associate Professor at Communications@Syracuse, Syracuse University's online masters in communications program, tells Bustle, "The fact that there is no effect on purchase intent does not necessarily make it an ineffective ad." Ads don't only aim to immediately drive you to buy something — they also might have a goal of just making you aware of a product or influencing your thinking in other ways. "So if the goal of the campaign is about consideration, the fact that the ad didn’t actually move purchase wouldn’t equal failure," notes Egan. "Even the authors suggest that they haven’t answered the question as to whether or not sex sells, but merely pointed out the complexity of effects."

Egan also points out that "males evaluate these ads more positively. That is who they are targeted to and likely written by," and so appealing to only them isn't necessarily considered a problem by advertisers. "There is a whole body of research that proves advertising is more effective at reinforcing current behaviors vs. encouraging new ones. Therefore, if you’re a brand popular among males and they’re seeing your ad for a product they use and are reacting positively to it, then you could be meeting your campaign goals."

In his press release, Wirtz pointed to Carl's Jr.'s recent decision to end their series of highly sexualized ads as proof that companies were realizing sexualized ads don't yield the results they want. “If the ‘sexy ads’ had been effective, it’s unlikely the company or ad agency would have made such a drastic change,” he said. There's no way to know if this is true, if this study will change advertising in America, or if sexualized ads are already changing to better reflect our social mores, as they have so many times in US history. The only thing the study can truly show us right now is, if sexualized ads leave you unmoved, you're far from the only one.