The study found the best way to get children to eat food they do not like was simply to give them repeated exposure to it.
In tests, children repeatedly offered vegetables were more likely to eventually eat them as those given rewards for eating their greens.
Psychologists from Ghent University in Belgium studied 98 pre-school children on ten vegetables which were either steamed or boiled – fennel, chicory, beetroot, courgettes, mushrooms, peas, leek, Brussels sprouts, spinach and cauliflower.
The taste tests revealed that chicory was the least liked vegetable.
The children were then given a bowl of steam chicory and told to choose how much to eat, while not sharing with other classmates.
After eight minutes they were asked to rate the dish as either ‘yummy’, ‘just OK’ or ‘yucky’ using cartoon facial expressions.
The trial went on twice a week for a month with a follow up taste test after eight weeks.
Children were split into three groups with one group asked to try the bowl of chicory repeatedly with no further encouragement while the other two groups were given rewards of stickers, a toy or verbal praise.
After the trial, 81 per cent of children who simply tried the chicory repeatedly liked it, compared to 68 per cent given a toy or sticker and 75 per cent given verbal praise.
The study team said: “All parents know how difficult it is to get children to eat their greens, with many offering rewards or treats in return for children finishing their vegetables.
“In our tests all three strategies had a similar level of success, suggesting that a reward may not have a substantial impact on willingness to eat.
“The results highlight that repeated exposure remains the best way to establish a liking of a food.”
The findings are published in the science journal Food Quality and Preference.