Which one would you choose? The healthy option or the chocolate bar? Perhaps your head says apple but your stomach says chocolate. If I told you the apple has 59 kilocalories and the Twix has 246, 18% of you would choose the apple. If I told you the apple has 247 kilojoules and the Twix has 1,029, 41% of you would choose the apple.
When people are faced with healthy versus unhealthy choices the way in which nutritional information is presented influences that choice. If you test this in people with a low prior interest in energy information the probability of choosing the apple increases from 3% to 59%.
We are exposed to this type of unit effect all the time. When we buy something for £9.99 we focus on the £9. When you are told a product costs just £1 a day rather than £30 a month and when a waiting time for treatment is 18 weeks rather than 4 and a half months.
The way we present information has a significant effect on the choices people make so we should consider that when giving health promotion advice.
How to Make a 29% Increase Look Bigger: The Unit Effect in Option Comparisons
Stop smoking, lose weight, and change your diet! As doctors we are constantly giving advice to people how to improve their health. We think these messages are clear. You are overweight, your blood pressure is too high and obesity increases blood pressure so lose weight. But much of this advice goes unheeded. How can we make it more effective. One way is to use the concept of appealing to Social Norms. We've all seen those signs in hotel bathrooms asking us to reuse the towels. Its good for the environment and after all you don't change your towel everyday at home? But only about a third of people actually reuse the towels. How can we increase that and does the way the message is conveyed alter the likelihood the towels are reused? A study published in the Journal of Consumer Research looked at this question and the results are interesting.
They had 2 messages for the hotel guests. A standard one focused on environmental protection "HELP SAVE THE ENVIRONMENT. You can show your respect for nature and help save the environment by reusing your towels during your stay." The other message had a descriptive norm informing people that a majority of other guests reused their towels: “JOIN YOUR FELLOW GUESTS IN HELPING TO SAVE THE ENVIRONMENT. Almost 75% of guests who are asked to participate in our new resource savings program do help by using their towels more than once. You can join your fellow guests in this program to help save the environment by reusing your towels during your stay."
The messages were randomly assigned to different hotel rooms. Towel reuse went up from about 30% in the standard message to 44% with the descriptive norm message. With further adjustment to the wording “JOIN YOUR FELLOW GUESTS IN HELPING TO SAVE THE ENVIRONMENT. In a study conducted in Fall 2003, 75% of the guests who stayed in this room participated in our new resource savings program by using their towels more than once. You can join your fellow guests in this program to help save the environment by reusing your towels during your stay", they increase towel reuse to 50%.
Descriptive norms improve towel reuse at least in hotel bathrooms but does this work in other areas. The Behavioural Insights Team, the so called Nudge Unit of the Cabinet Office, looked at charitable donations in wills. The average donation was £3,300. When people rang to book a will-writing appointment they were randomly assigned to one of two groups of will-writers. The first took their details and then asked "Would you like to leave any money to charity in your will?". The second said "many of our customers like to leave money to charity in their will. Are there any causes you’re passionate about?” The first or "Plain Ask" method had no effect on donations but the second social normative doubled the average donation to £6,661.
The results are important for hoteliers and charities but also have implications for doctors and nurses trying to improve the uptake of health promotion programs. If we can introduce social norms into our recommendations this is likely to improve the chance that our advice is followed.
Dr Richard Bogle
The opinions expressed in this blog are strictly those of the author and should not be construed as the opinion or policy of my employers nor recommendations for your care or anyone else's. Always seek professional guidance instead.