Recently, the Behavioural Insights Team began altering the letter sent to British citizens if they failed to pay taxes on their car. The traditional letter was all text, informing the subject that if they didn’t pay now they would be hit with various penalties, including a clamped or and hefty fines. To increase the effectiveness of the letter, the scientists began experimenting with various forms of personalization. The first variant involved making a more specific threat, telling recipients that they would lose their particular model of car if they didn’t pay the tax. The second variant featured a personalized visual, so that the letter came attached with a photograph of the actual car question. While both approaches increased compliance, the customized picture was the most effective—it increased the compliance rate from 40 to 49 percent.