Can graphic warnings steer us away from junk food?

Graphic and negative messages on food packages could be a way to keep us from grabbing an unhealthy snack, a new study shows.

Junk food has little to recommend it to the smarter parts of our brains, but to our impulsive side, taste is all that matters. We might strategically avoid the grocery store candy aisle, but we all have to pass through the checkout where the lure of the sugar fix can overshelm our impulses.

The checkout trick is just one of a multitude of “environmental cues” that food companies use to market their products, from packaging to lifestyle messages and popular culture, says Stefan Bode of the School of Psychological Sciences at the University of Melbourne.

But how alluring would that chocolate be if the packaging was slapped with a picture of decaying teeth or a diseased heart?

New research suggests that just like warnings on cigarette packaging, when it comes to junk food, the more graphic and negative the message the better. But positive imagery or negative text-only warnings can work, too.

junk food warning labels
An example of negatively framed text and graphic messaging and one of negatively framed text and graphic image messaging. (Credit: via U. Melbourne)

Power of cues

The research, conducted as part of a PhD project by Daniel Rosenblatt, reinforces arguments that mandatory health warnings on unhealthy food could be an effective element of a comprehensive approach to improve diets and combat rising rates of obesity-related chronic diseases like diabetes, heart disease, and some cancers.

“The food industry uses all sort of positive cues to encourage you to eat, playing on taste, how it will make you feel good, making it look appetizing, but when it comes to unhealthy foods—this is dangerous,” Bode says.

“The idea of warning labels is to use the power of cues, but in the other direction, and use health-focused cues to nudge people towards healthier food. And what we’ve found in Daniel Rosenblatt’s experiments in the laboratory is that if you want to stop people choosing fatty and sugary packaged foods, health warnings actually work.”

Real-world choices

Rates of obesity worldwide have almost tripled since 1975. Around 13 percent of adults worldwide are now obese the world over, and 39 per cent are overweight. The epidemic is worse in richer countries where nearly 20 percent of adults are obese.

Beyond hypothetical surveys there isn’t enough research into what sort of food labelling would be the most effective. So researchers developed an experiment in which hungry participants actually received a portion of food to eat that matched their choices before and after viewing different health warnings.

“Most of the research in this area is based on surveys in which researchers ask people whether they think various messages would change their behavior, but we know there can be a massive mismatch between people’s intentions and their actual behavior,” Bode says.

“In our experiment we tried hard to approximate the real world and have our participants make a decision with immediate, real consequences.”

The team recruited 95 participants who hadn’t eaten for at least four hours and told them that at the end of the screen-based experiment they would each receive a snack food that matched their preference.

Self-control, not impulse

Each participant was then shown color pictures of 50 different snack foods such as chips, chocolate bars, biscuits, nuts, fruits, and vegetables.

They were asked to rate on a scale how much they would like to eat each food at the end of the experiment.

Participants were then shown 10 different health warnings from one out of five possible categories, text-only positive messages; text-only negative messages; positive text and graphic messages; negative text and graphic messages; and, lastly, messages that only showed scrambled images and unreadable text as a control.

They then had to rate a similar set of 50 snack foods that were closely matched on health and taste attributes to see if the health warning had influenced their preferences.

The findings show that while control messages and positive text-only messages had no impact, negative text-only messages, and imagery combined with positive text were both effective in encouraging people to revise their initial choice for a healthier option.

But the strongest effect was observed for negative text combined with imagery. It was twice as effective in making people change their minds as the other messages.

We neglect this factor when choosing healthy food

To try and better understand what was going on in the brain when people evaluate foods after seeing health messages, researchers also monitored participants’ brain activity using non-invasive electroencephalography (EEG), in which electrodes are attached to the head.

The researchers wanted to know what kinds of thinking processes were influenced by the warning messages. The results suggest that warning labels prompted participants to exercise more self-control, rather than act on impulse. The brain signals allowed them to “see” how the warning messages were working.

Your teens may actually take healthy food rules to heart

“One of the aims of the project is to try to unravel what mechanisms are at work when we make choices on what to eat so that we can develop effective health messages,” says co-researcher Helen Dixon, a behavioral scientist with the Cancer Council of Victoria and an honorary researcher at the University of Melbourne.

“Strong cues like anticipated taste, tend to work on us in a more unconscious way, and therefore health messages need to disrupt these more impulsive, hedonistic responses to foods and make people consciously consider the health implications of their choices.”

The findings appear in the journals Appetite and NeuroImage: Clinical.

Source: University of Melbourne