What happens to the brain when you see a billboard – and does it still light up on repeat viewings? JCDecaux decided to find out.
It’s high time advertisers talked about the value of frequency in out of home, says JCDecaux’s Victoria Parsons.
The outdoor advertising company has conducted new research here in Aotearoa showing just how powerful this metric is for campaigns.
“We find there’s an obsession with reach, which might be right for television, but for a channel like out of home – where there’s these short sharp moments and you’re in the middle of a commute – frequency is a really important aspect that is being undervalued,” says Parsons, who is JCDecaux’s brand strategy and insights director.
Watching TV on the sofa is a completely different environment to being out in the world, she adds.
“When you’re watching TV, you’re not thinking, ‘Am I going to be hit by a car? Is there a tiger in the bushes?’ Your neural sense is quite different when you’re outdoors.”
There’s also limited understanding about frequency – prior to JCDecaux’s work, there had only been one other study on optimal frequency. It was conducted in the UK, using billboards in a VR cityscape environment. The results tested recall and what people enjoyed about the ads they saw, and suggested that a frequency of nine to 12 exposures was the sweet spot.
JCDecaux’s study took it one step further – looking at how the brain actually responds when it sees an out of home campaign. Participants wore head caps to capture their neural activity and the researchers measured memory encoding – the brain’s ability to learn and retain new information.
Delving into data
For JCDecaux’s large format billboards, they saw this metric spike at each exposure, before dropping off at a frequency of nine.
This shows people were learning each time they encountered the ad, deepening their understanding and engagement with the campaign, Parsons explains.
“So you see the first hit with the campaign is the biggest, because your brain has to go, ‘What’s that all about?’ But then each subsequent frequency, it’s saying, ‘I’m now looking at the price,’ or, ‘I’m looking at the words,’ or, ‘I’m looking at the picture.’ And it’s adding to its understanding.
“When the metric starts to dip down at nine, the brain’s gone, ‘I’ve taken everything there is to take out of this.’ It’s not adding to its learning at that point.”
Pick up where you left off
Another realisation is that length of engagement does not influence memorability – meaning people didn’t need to stare at the campaign. They already knew what it was and would “pick up from where they left off,” says Parsons.
“That’s why memory encoding continues. It’s because you’re adding to your understanding to the point of wear out, but you’re not starting at the beginning each time.”
It’s the same mechanism that means we don’t have to sit and study our loved ones and colleagues each time we see them – our brains understand who they are and automatically makes connections, she adds.
But these findings don’t mean you should be bombarding your audience with the same creative over and over again, she says.
For a campaign with a frequency of 17, brands could use three pieces of creative that look the same, but have different messaging. Or perhaps start with a hero piece of content then swap to one focused on the product, but with the same headline.
It’s like speed dating
So marketers can say: “This is how the campaign’s going to roll out, how are we going to use these frequencies to get the best outcome?” says Parsons.
“We liken it a bit to a speed date. If you went on a speed date and you tried to say everything there was to say about you in that first minute, the person would think, ‘Whoa!’ And they wouldn’t want to have a second date.”
Sometimes, brands do the same with out of home, attempting to explain everything there is to know about the brand, product and service, in one to three seconds.
“Which is impossible, because you just see it and you think ‘information overload’, and look somewhere else,” explains Parsons.
These results change depending on the ad placement. JCDecaux tested its large format billboards, which delivered maximum memory encoding and engagement, against Smartframe and street furniture sites.
Smartframe achieved record emotional intensity and the highest attention, while the brain took
much longer to warm up to smaller spots like street furniture.
Here, data showed memory encoding didn’t start to peak until the brain has had five to seven exposures, she adds.
“That’s important because some brands are now starting to buy digital street furniture to a frequency of three and then moving to another location,” says Parsons.
“So instead of reaching one million people, they reach one and a half million – but they’re only giving them a snapshot.”
This story comes from NZ Marketing magazine issue 83, Jun-Aug 2025. Why not subscribe? Get four issues a year for just $50 (including delivery) if you autorenew.
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