Even the most well-designed and accessible websites may inadvertently have inaccessible elements — advertisements. Pesky pop-ups or bothersome banner ads may be easy for many people to navigate away from, but for those who use screen readers, ads that are not developed with accessibility in mind can make browsing online a frustrating experience.
Allen School Ph.D. student Christina Yeung alongside professors Franziska Roesner and Tadayoshi Kohno wanted to understand just how problematic inaccessible ads can be to users who rely on screen readers. By auditing how ads use, or do not use, accessible elements and pairing that with interviews with blind participants about their browsing experience, the researchers found that the overall online ad ecosystem is fairly inaccessible for users with screen readers. However, encouraging ad platforms to adhere to existing web accessibility guidelines can help make surfing the web a better experience for everyone.
The researchers presented their paper “Analyzing the (In)Accessibility of Online Advertisements” at the 2024 ACM Internet Measurement Conference (IMC) in Madrid, Spain, last November where it received the Best Paper Award.
“Online ads are everywhere and so pervasive. If you’re browsing on your phone, or even have an ad blocker on your laptop — you will still see ads,” lead author Yeung said. “But because ads are designed with the intent to visually tell you what’s going on, for those who are blind and use screen readers, they can be even more problematic in ways that other people might not think about on a day-to-day basis.”
Yeung and her collaborators analyzed the behavior of over 8,000 ads across 90 different websites based on how well they adhere to Web Content Accessibility Guidelines (WCAG) best practices. Over the course of a month, the team looked at whether the ads disclosed their third-party content status to screen readers as well as their use of HTML assistive attributes such as alt-text and aria-labels. These elements ensure that screen readers can perceive images and other non-text elements on the ad. They also tracked the number of interactive elements each ad had and if there was any missing text associated with links or buttons. For an ad with 15 interactive elements, someone who uses the tab key to maneuver through ads would need to press it 15 times to reach other content on the site. If an ad has a button without associated text, instead of telling the user what it does, the screen reader will just say “button.”
The researchers found that the majority of the ads contained inaccessible elements. More than half of the ads had no alt-text at all, or had empty or non-descriptive strings. Many assistive attributes included non-descriptive language such as “ad” or “image.” They also noticed that ad developers were using title attributes to provide information, contrary to WCAG guidelines. Title attributes can provide more context to specific HTML elements, appearing as a tooltip when a user hovers their mouse over the element. However, not all screen readers can consistently interact with them.
“Inaccessible ads have two primary problems,” Yeung said. “First, people can’t differentiate what the content is, so they can’t even make the decision as to whether or not they want to interact with it. Secondly, ads that are designed poorly really do negatively impact browsing in a way that can be quite cumbersome.”
Yeung then interviewed blind participants who use screen readers to understand just how burdensome these poorly-designed ads can be. All of the participants reported that these ads both distracted and detracted from their web browsing experience as they were difficult to navigate away from. Because many ads did not disclose their third-party status, participants often had to use context clues to identify them. For example, if someone was on a news site and they suddenly hear content about furniture, they would know that the furniture content is the ad. While the researchers did not evaluate pop-up ads in the study, participants brought up how frustrating these ads are because they are difficult to close and participants struggled to get back to where they were on the page before the ad.
Only a few large companies dominate the ad landscape, so refining how they adhere to accessibility guidelines can make a noticeable difference. Major ad platforms such as Google, Yahoo and Criteo could create and enforce policies requiring ads to provide meaningful information to screen readers in the HTML attributes. They could also go a step further and develop templates that encourage using assistive attributes and reject ads with generic or missing information, Yeung explained.
“By making some fairly minor changes, we can improve the ecosystem in a way that makes browsing more equitable for everyone,” Yeung said.
Next, Yeung is looking into people’s perceptions of the data collection practices of different generative artificial intelligence companies.
Read the full paper on ad inaccessibility.