Celtra Interscroller

I designed an ad format that is used by over 400 publishing giants, “inspired” Google and other adtech vendors to follow suit, and was recognised by the IAB as not hated by users.


Banners are the most ubiquitous form of digital advertising. Yet, they remained the same awkward rectangles transplanted from a printed page since the first one was published on hotwired.com in 1994.

Entrusted by numerous publishers as their creative adtech partner, Celtra saw an opportunity and need for innovation. I was assigned to lead research and development of a new ad format, reported directly to the CPO, and worked closely with the key internal stakeholders responsible for ad delivery technology.

We are all banner blind, or are we?

The click-through rate benchmark dropped below 1%. The internal joke became that digital ads are like desperate single men: aggressive, pushy, and annoying. But if people truly hate ads so much, why do Super Bowl and hall of fame ads have millions of views on YouTube? If ads are viewed on-demand, they are no longer ads.

So what kind of alchemy can turn commercials into content? Film and TV studios perfected their matchmaking with product placements. But it’s the printed magazines that were forced to master the “dark arts” of ad transcendence. How? With carefully selected ad placement, high production quality, and clever visual communication. The glossy full-page spreads we like to flip through in waiting rooms and airport lounges.

These insights led to the following strategic hypothesis:

  1. People don’t hate ads; they hate garbage ads
  2. Banner blindness is a consequence of intrusiveness — they would get noticed if they were less annoying
  3. To get you first need to give — better ad UX and production quality would change audiences’ attitudes towards banner ads

Eye-tracking UX study

But how do you measure annoyance, especially over the wire? And how reliable are research methods for gauging audiences’ emotional reactions anyway?

We were sceptical of traditional probes, self-reports, and interview methods. If we wanted to get reliable non-opinionated data, our instrument would have to get as close to human perception as possible.

I designed an eye-tracking A/B test to learn about people’s responses to the visual intensity of ads and commissioned an independent UX research company in Slovenia to carry out the study.

It took place in-person and in a tightly controlled user-device-media environment. The user would freely interact with a live version of a well-known news publisher website using a PC laptop, iPhone, or iPad while wearing an eye-tracking headset. After a placebo test run to get comfortable with the set-up, they were asked to choose and read an article.

During the reading, they encountered a standard 300×250 MPU ad exposing them to one of the four experiences of varying visual intensity:

  1. static photo
  2. cinemagraph photo
  3. sequence of photos
  4. video footage

Each ad promoted the same dummy energy drink brand to minimise the subject (dis)interest bias. Each person participated in one recording session using one device and was exposed to one predetermined ad type. The study involved 144 participants of a general, albeit culturally homogenous, Slovenian audience.

It’s safe to say ads are definitely seen. Especially on smartphones where they take almost a third of the screen’s real estate, making them virtually impossible to overlook. On mobile devices, the audience’s gaze was sustained the longest by the cinemagraph type, and on the laptop, it was the image sequence.

What seems to work best is the golden middle: motion in moderation.

Ideation of a new better format

We steered our synthesis and selection process based on the following principles:

Intrusion begets defence. To sustain a person’s attention and elicit engagement, never limit their control of the interaction, block, cover, or otherwise impose.

Instantly provide value or end up ignored. Achieving that requires a big enough canvas to showcase high-resolution images and large-font copy.

If you’re a pleasure to deal with, your shortcomings are easier to forgive. People expect gesture-based interaction and smooth UI transitions when using mobile apps, so an ad has to look and feel like a natural extension of the publisher’s UI.

I explored possibilities of:

  • frictionless opt-in ad experience interaction
  • novel ad placements within common apps and website types UI patterns (news, games, utility, etc.)
  • standard device screen, viewport, and image aspect ratios concerning responsive behaviour constraints

Out of ten produced concepts, a few were developed into prototypes, three of which run as pilot campaigns, and one that became a GA product: the Interscroller.

To support the product launch and explain its design rationale, I wrote It’s Time to Shape the Next Generation of Mobile Display Ads.

Launch and reception

It debuted on Telegraph.co.uk in October 2014 and was launched in November the same year with Opera Mediaworks, AdTheorent® and Allrecipes as media partners.

"The Interscroller unit is a key component within a powerful trend where mobile ads are continuously adapting to fit native mobile interfaces and experiences to ultimately become more beautiful and memorable.
Scott Swanson, President, Global Advertising Sales, Opera Mediaworks
Celtra's Interscroller ad format helps us deliver an impactful combination of storytelling and branding features, along with a superior user experience."
Yolandi Oosthuizen, Director of Creative Services, AdTheorent

A month later an independent consumer research was published stating:

The ad worked well for all ages, but Millennials showed a particularly strong response to the way the scroller revealed itself, with 44% expressing positive feelings about it (as compared to 31% of those over 35 years old).
Interactive Advertising Bureau (IAB)

The aftermath

In 2015 and 2016, several competing adtech vendors began offering their scrolling ad formats. Among them, the usual suspect.

Google is bringing new ad types to AMP, including those annoying flying carpet ads.
Tech Crunch

Unfortunately, the competitive products were less concerned with user experience. Instead, they exploited the scrolling to consumer’s detriment, adding their share of dirt to a rapidly growing pile of fraud scandals, malvertising cyber attacks, erosion of user privacy, and other malicious practices that avalanched an ad-blocking boom.

Consequently, in 2017, the leading advertising organisations formed The Coalition for Better Adsto measure consumers’ preferences about the types of ads they least prefer, in order to help the global marketplace take steps to deliver a better ad experience.

Around the same time, Google announcedthey plan to have Chrome stop showing ads […] on websites that are not compliant with the Better Ads Standards starting in early 2018. Even though the “Full-screen Scrollover Ad” was among them, the Interscroller was never intended to be on the shitlist.

As a response to market frenzy, I wrote an article about Why User Experience Keeps Getting Scrolled Over By Ad Tech.

By 2018 the Interscroller regularly run on more than 400 global publishers including: Vice, Bloomberg, The New Yorker, The Guardian, The Atlantic, Conde Nast, Mail Online, and other media giants.

It’s not uncommon to see it in the wild to this day.

Engineering: J. Jančar, K. Slavič, G. Kozak
Product management: G. Lamden, T. Štrok
Data analysis: N. Smith, L. Karelis