The study, designed to gauge the power of advertising, revealed that boys and girls as young as three found food tastier when they thought it was made by a big brand.
The phenomenon is not restricted to fast food. Even milk and carrots were deemed tastier by youngsters if they believed they had been bought at McDonald's.
The research, from Stanford University in the U.S., comes amid growing concern about the influence of advertising on children's health and follows the British ban in April on junk food manufacturers promoting their products during TV programs targeted at under-16s.
During the study, children aged between three and five were asked to rate five foods for tastiness.
Each child was given two identical samples of each food, one in McDonald's packaging and one in plain wrapping. If the children were not influenced by branding, it was expected that they would find both samples equally tasty. As it turned out, the McDonald's-labelled chips were judged tastier by six times as many children as voted for the plain-packaged chips. Chips and chicken nuggets carrying fast food branding also won the children's approval.
Researcher Dr Thomas Robinson said, "Kids don't just ask for food from McDonald's. They actually believe that the chicken nugget they think is from McDonald's tastes better than an identical, unbranded nugget.
"It's a really unfair marketplace out there for young children. It's very clear they cannot understand the persuasive nature of advertising. Parents don't choose for their children to be exposed to this.
"Parents have a very difficult job. It may seem easier to give in to their child's plea to go to McDonald's than give in to the many other hundreds of requests during a day.
"This is a company that knows what it's doing. Nobody else spends as much to advertise its fast food products to children." He added, "No one is going to propose we totally stop industries from promoting their products. But there is a very good argument for regulating and limiting marketing to children."
Further analysis showed that the link between brand and perceived taste was strongest among children who ate fast food more often and among those with more than one TV set at home.
Writing in the journal Archives of Pediatrics & Adolescent Medicine, the researchers said, "These results add evidence to support recommendations to regulate or ban advertising of the marketing of high-calorie, low-nutrient foods and beverages, or all marketing that is directed to young children."
Tam Fry, of the Child Growth Foundation, said the study underlined the importance of teaching even the youngest children about healthy eating. He added, "Gaudy, colorful packaging is tremendously attractive. If we could do the same with broccoli, it would be wonderful."
McDonald's said it actively tries to promote healthy food to children.
From the August 13, 2007, Prepared Foods e-Flash