Fox to Test Indy 500 Viewer Excitement Via Sweaty Palms

To understand just how gripping Indy 500 racing is, Fox will have a group of viewers—both at home and within The Brickyard—wearing biometric trackers on their hands this Sunday. By measuring sweat gland activity, the broadcaster hopes to demonstrate the unique pull of high-octane sports and optimize its presentation for maximum engagement in a world of distraction.  

Fox has been running similar experiments for multiple years with Portuguese media measurement company Mediaprobe, having previously conducted tests with viewers in laboratory environments.

“A lot of the motivation for us to do this project and to work with Mediaprobe generally is that people are unreliable narrators,” Fox Sports president of insights and analytics Michael Mulvihill said. “And so, if you can move into measuring involuntary responses, I think you’re just getting something that is more reliable, hopefully more insightful, and it might just be a richer data set.”

Mediaprobe readouts from the Fox-broadcasted 2025 Super Bowl could impact how the company covers its next big game in 2029, Mulvihill added. Behavioral fan data also serves to entice advertisers to spend more on sports. TV ratings only tell part of the story.

“We’re always talking about the emotional power of sports, and we believe it intuitively,” Mulvihill said. “Our advertisers, I think, believe it intuitively. When you have an opportunity to actually quantify it, I think that’s potentially really useful.”

Mediaprobe works with 3,500 households in the U.S., where TV viewers have agreed to wear a small device in the palm of their hand that measures what the company calls “Galvanic Skin Response,” which is connected to subjects’ sweat gland activity in response to what they’re watching. The tracker doesn’t differentiate between positive and negative emotional responses, though participants use an app to log additional context. 

“Peaks and valleys, that’s how we love to look at the data—when did it spike, when was it low,” Mediaprobe SVP of client success Beatriz Ribeiro said. “First, we thought, let’s measure the race with our panel at home, but then we thought, no, let’s get the pre-race, the race and post-race, also at home versus on-site, so we get these six hours of data.”

This weekend will be the biggest in-person activation for the technology. Fox bought 33% of IndyCar in 2025, giving it additional incentive to develop the live event as well as broadcast components. 

Mulvihill said “350,000 people come to this thing every year, so it’s obviously already pretty good.” An average of more than 7 million tuned in on Fox last year, delivering the race’s largest rating since 2008.