Inside the Nudge Unit

Cialdini et al.’ s work also gave clues about messages that might work even better. His work suggests that people are more influenced by the behaviour of those they see as being more like themselves than by people in general. For example, guests are more likely to reuse hotel towels, thereby saving energy, if told that previous guests had done so, rather than people in general. On this basis we tested the line that ‘most people in your local area pay their tax on time’, and found this raised the payment rate by more than 2 per cent over control. Similarly, a little known exception to the rule that the more litter on the ground, the more likely a person is to discard a leaflet is that you are even less likely to drop litter in an otherwise perfectly clean environment with a single piece of litter than one with no litter at all. The single piece of litter seems to remind us that littering is the exception, and that disposing of it properly is the norm. This finding helped to shape the line that ‘most people with a debt like yours’ had already paid (‘ debt norm’). This was even more effective than the local social norm. Combining the two approaches into one, explaining that most people in your area had already paid, and that you were one of the few yet to do so raised the repayment rate by 5.4 percentage points, or an impressive 16 per cent increase in payment rate relative to the control letter.