Monday, December 21, 2009

Psyblog: Ads For Unhealthy Foods Increase Children’s Consumption 45% (11/24/09)

So snack food advertising makes most people eat more. After viewing them children eat almost twice as much, adults (if they're women on a diet or men) eat around a third more and this effect carries over to foods other than those being advertised and after the adverts have finished. Simply avoiding snacking while watching TV isn't going to cut it.
Curious? Read onwards. The first experiment involved kids.
In their first experiment 118 kids, 7 to 11 years old, were sat down to watch a cartoon with advert breaks at the usual intervals. Each child was randomly assigned either to be shown four adverts for snack foods or four adverts for other non-food products aimed at children. The commercials used were taken from actual children's programming and the snack food adverts were all for unhealthy foods like sugary breakfast cereals and potato chips.
While they watched the cartoon, children had a bowl of cheddar cheese "goldfish" crackers in front of them which they were told they could snack on if they wished.
The experimenters were very thorough and collected all kinds of other information about the children like how hungry they were, how much television they normally watched, whether they happened to particularly like the snack that was used to measure eating behaviour, whether they were overweight, whether they had a TV in their room at home and a host of other variables.
Afterwards the experimenters measured how much of the snack the children had eaten and compared the two groups. Children who had watched the cartoon which included adverts for snack foods ate 45% more of the "goldfish" crackers than those who saw non-food adverts.
None of the other variables measured had a significant effect on how much the children ate, except their like (or dislike) of cheese crackers. It didn't matter if they watched more or less TV at home, were over- or under- weight, or how big their appetite was usually. Over and above anything else it was clear that the snack food advert caused children to eat much more of an unhealthy snack.
The second experiment involved adults, specifically college students aged 18 to 24 years old, some of which were also on diets. As one would figure, the dieters would be more likely to eat more.
For this experiment a more sophisticated set-up was required in which participants didn't have snacks in front of them while they watched TV, but snacks were presented to them afterwards in what was apparently an unrelated experiment.
This time instead of cartoons the participants were shown 'Whose Line Is It Anyway?', an improvisational comedy show. They were told the adverts had been left in because the psychologists were interested in the effects of TV on mood and they were in the 'comedy condition'. Actually, of course, everyone saw the same comedy show, it was just the intervening adverts that were different.
All the participants were randomised into one of three groups. In the first they saw adverts for snack foods, in the second they saw adverts for nutritional foods and in the third they saw adverts for non-food products. After watching the show they were taken to another room for what they were told was a different study involving tasting and rating some snack foods. The snack foods offered varied in healthiness: there were vegetables, multi-grain chips, cookies, trail mix and snack mix. Participants were told to taste each one but left to eat as much or as little as they liked. Afterwards the experimenters measured exactly how much each person had eaten.
Once again the snack-food ads had weaved their magic as those who had seen the snack ads ate significantly more than those who had seen either the nutrition ads or the non-food ads. But when the experimenters looked more closely at who had eaten more they found two particular groups were responsible: the restrained eaters and men (but not unrestrained women). Both had eaten, on average, about one-third more snack food if they had seen the snack ads compared with those who had seen either the nutrition ads or non-food ads.
Perhaps surprisingly the ads for unhealthy snack foods didn't only boost how much of the unhealthy snacks people ate, they boosted how much people ate across all the options available, healthy vegetables and semi-healthy trail mix included. The only exception was women who weren't on a diet who ate no more after being shown the snack food ads than other non-food ads.
Here's the kicker.
The vast majority of adults in the second study, when asked later, had no idea that watching snack food ads would make them eat more, despite the relationship being unremarkable in retrospect. And this is exactly what Harris and colleagues suggest is the key to defending oneself against adverts: understanding the powerful influence they can have on our behaviour, even without our knowledge.
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