Those extra-large ad units the Online Publishers Association introduced 15 months ago are hard to ignore – and now the OPA has the research to prove it. 

The trade association today released the results of a biometric study designed to assess the effectiveness of the large format OPA ad units, which include the Pushdown (which opens at 970x418 before collapsing to 970x66 after seven seconds); the Fixed Panel (a 336x700 unit that scrolls with the user up and down the page); and the XXL Box (which opens at 936x648 before shrinking to 468x648).

The study, which the OPA conducted with Innerscope Research, found that 90% of participants noticed the ad units in the first 10 seconds of entering a webpage. Surprise!  More importantly, perhaps, the study found that two-thirds of users returned to look at the OPA ad units after spending time elsewhere on the page.

In addition, 73% of users who looked at the ads (“fixated” in Innerscope’s terminology) displayed a stronger emotional response to the advertising than to the rest of the webpage. On average, subjects fixated on the OPA units 15 times while surfing the test sites (CNN.com, msnbc.com and NYTimes.com).

To OPA President Pam Horan, this means the ads aren’t just bigger, they’re also more interesting. “It demonstrates that there’s real value there,” Horan said in an interview. “Advertisers can feel confident that these units are not obtrusive, and that they can deliver brand experiences that help them to connect with the consumer.”

Of course, Innerscope doesn’t measure whether those emotional reactions – measured through a combination of eye tracking, skin sweat, heart rate, breathing and motion – are positive (“wow”) or negative (“ew”). But Horan notes that the OPA ad units used in the survey have achieved favorable likeability scores of 6.3 on a 9-point scale. That score strikes me as fairly neutral, but Horan countered, “In my book, that is fairly significant. Nobody ever answers likeability questions in the extremes.”

She also noted the ads had a positive AQ score, which Innerscope uses to measure emotional response through a combination of self-reporting and biometrics. “This tells you that it’s not intrusive, that there’s actual likability,” she said.

I asked Horan how advertisers can correlate these results with the more tangible ROI-related outcomes that many marketers are focusing on these days.

“It depends on your objectives,” she said. “So much of online advertising has been direct, and the key metric has been the click. But there are other ways brands can deliver their marketing messages. If it’s about changing perceptions, you need to apply the right metrics to that – using clicks to measure perception is ludicrous.

“This research shows that branding online can be really effective,” she added. “These ads give marketers a larger palette to deliver their brand messages, connect with consumers and change perceptions, without the focus on the click.”