Persuasive ad copywriting: Using behavioural science insights to drive better results on Facebook

Did you know that ad copy that uses insights from the behavioural sciences discipline can lead to striking improvement in Facebook campaign performance? In a recent experiment, we ran for a UK retail client, the ad variation informed by behavioural insights was 75% more engaging than the original ad copy.

Creative and ad copy tests are common practises on social media platforms. However, to get the most out of your ad copy testing the variations should be meaningfully different. This is where the behavioural insights come in, helping us frame the same message in different ways to maximise our learning and effectiveness.

But first, let’s clarify what we mean by ‘ad copy’ on Facebook?

On Facebook, the ad copy refers to the text displayed as part of the advertisement (e.g. the Primary Text, Headline and Description). After the displayed creative (e.g. the image or video), people focus on the message.

Source: Facebook Blueprint: Add Lightweight Motion to Stills

How to level up your ad copy with behavioural science

Behavioural science is the academic discipline dedicated to uncovering the patterns behind human decision making. A large body of academic work investigated the factors that influence consumers when deciding on what to purchase. Using these insights to frame ad copy can have remarkable improvement on campaign performance. The insights listed below provide a useful starting point:

  • Social Norm – humans are social animals and so we are always on the lookout for what others purchase. We especially rely on this cue when we purchase from an unfamiliar product category. Looking at reviews, quality ratings all rely on this principle guiding consumers to make purchasing decisions (Asch, 1951; Goldstein, Cialdini & Griskevicius, 2008)
  • Authority Bias – humans are wired to look to authority figures and experts when making purchasing decisions. We tend to rely on this more heavily when making a high-stakes decision or when we do not have a strong preference. A dentist endorsing a particular toothpaste or Novak Djokovic wearing Lacoste are both manifestations of this principle (Milgram, 1963; Cialdini 2007)
  • Cognitive fluency – in general, the simpler a message is the more likely that the consumer will pay attention to it and then perform the desired action. Furthermore, if a message ‘feels’ easy to read, it is more likely to be evaluated as true, familiar, likeable, probable, funny or compelling (Unkelbach & Greifeneder, 2013)
  • Scarcity – we evolved to value resources that are scarce and difficult to obtain. Services and products that are (perceived as) less readily available are more desirable and valuable. Messages that mention time restriction or limitations in quantity both build on this principle (Aggarwal, Jun & Huh, 2011)
  • Saliency – consumers tend to engage with messages more when it connects to one of their active goals. For example, consumers looking to buy Mother’s Day gifts engage better with ads when it calls out the gifting occasion as the first thing in the ad copy (Mormann et al., 2012)
  • Mental accounting – consumers tend to use different mental accounts when purchasing from different product categories or occasions. For example, when promoting a line of perfumes, the message “Fragrances to reward yourself for that special occasion” would nudge users to buy a more expensive perfume than when using the message: “Fragrances to elevate your everydays” (Thaler, 1985)

In our most recent experiment, the scarcity framing resulted in an ad that was 75% more engaging than any of the alternatives. As such, framing the messaging using the above insights has the potential to level up your ad campaigns. However, these insights are only the tip of the iceberg. The academic literature has identified an abundance of heuristics and biases that could inform how we frame the ad copy.

Luxury handbags in the Gulf countries, a case study

We ran a month-long activity in some of the Gulf countries advertising an exclusive set of luxury handbags. As part of the campaign, we conducted an ad copy experiment. Besides the generic ad copy provided, three further versions were introduced:

  • Free Delivery – calling out ‘free delivery’ as the first thing in the ad copy
  • Social norm – calling out that the products are popular
  • Scarcity – emphasising that the products are exclusive

The four variations were all put into the same ad set to allow Facebook to optimize the budget based on the performance of the different versions to achieve the most optimal performance.


“Free Delivery” was the least engaging at a conversion rate of 0.15%, followed by the social norm framing at 0.17% and then the generic ad copy at 0.20%. The scarcity framing had the strongest performance at a striking 0.35% conversion rate.


At first glance, the conversion rate results may be surprising, especially given the Free Delivery version had the lowest Conversion Rate (CvR). However, it’s worth noting that free delivery may be less significant for a buyer in comparison to the high price of a premium product. The high-end nature of the products may also explain why they did not align well with the social norm framing as these consumers may not seek to join a trend or to be like others. Instead, they may prefer to be perceived as unique, which may also explain why the scarcity framing worked so well.

Notably, the scarcity framing only resulted in the second most conversion event. This is due to the breakdown effect that informs how the Facebook algorithm works. The algorithm strives to provide the best overall result with the four ad variations by delivering the specific variations to those sub-sets of the target audience who would most likely perform the conversion action. This implies that putting all the budget to scarcity variation would have been counterproductive as there are not enough users in the group to keep the current high level of engagement rate, otherwise, the Facebook algorithm would have allocated all the budget there. In fact, most of the time funnelling all the budget through the best performing ad usually does not lead to the best performance. So, to achieve the best possible results we would always recommend running more than one ad copy variation.

Adding ad copy variations, especially when informed by sciences, is a win-win. It does not only help drive better results but at the same better captures invaluable insights about your target audience. For example, in this case, adding the four variations delivered better results than if we only ran the campaign with only one of the above-mentioned ad variations. Also, it taught us that Scarcity framing is particularly engaging so should be tested in future campaigns promoting similar products. Furthermore, we also learned that Social Norm and calling out Free Delivery do not resonate well with this type of audience, and next time other framings should be tested.

Finally, it is important to emphasize that these insights are context-specific and may work better in some instances than in others. It is always crucial to consider the brand and product and the associations people have towards them when determining which behavioural insights to utilise. For example, using social norm framing to promote high-end brands, such as Ralph Lauren, may be counterproductive as the very reason customers buy them is that they can feel exclusive. On the other hand, brands that are perceived as affordable and accessible may not be successful with scarcity framing.


Insights from the behavioural sciences discipline are often overlooked when running ad copy experiments. However, it may have a tremendous impact on the effectiveness of your Facebook campaigns. In our most recent study, we found that the ad copy variation that was crafted using a behavioural insight was 75% more engaging than any of the alternatives. Using these insights is an easy win, as it both improves performance and captures insights of the target audience.


Asch, S. E. (1951). Effects of group pressure upon the modification and distortion of judgments. Groups, Leadership and Men, 119–124.

Cialdini R. (2007). Influence: The Psychology of Persuasion. HarperCollins: New York.

Goldstein, N. J., Cialdini, R. B., & Griskevicius, V. (2008). A Room with a Viewpoint: Using Social Norms to Motivate Environmental Conservation in Hotels. Journal of Consumer Research, 35(3), 472–482.

Milgram, S. (1963). Behavioural Study of Obedience. Journal of Abnormal and Social Psychology, 67, 371-78.

Mormann, M. M., Navalpakkam, V., Koch, C., & Rangel, A. (2012). Relative visual saliency differences induce sizable bias in consumer choice. Journal of Consumer Psychology, 22(1).

Unkelbach, C. & Greifeneder, R. (2013). The experience of thinking: How the fluency of mental processes influences cognition and behaviour. Psychology Press

Aggarwal, P., Jun, S. Y., & Huh, J. H. (2011). Scarcity messages. Journal of Advertising, 40(3), 19-30.

Thaler, R. H. (1985). Mental accounting and consumer choice. Marketing Science, 4(3), 199–214.