Three key responses behind food neophobia, the rejection of new foods in both adults and children

Yuk! That short expressive word, the trademark of the fussy eater, is dreaded by thousands of parents.

Yet picky eating, and in particular mistrust of new sorts of foods, is not confined to children.

According to Dr Yolanda Martins of the School of Psychology at Flinders University, South Australia, there are three key responses behind food neophobia - the rejection of new foods - in both adults and children.

"There is distaste, a dislike of the food's taste or smell; there is danger, the idea that eating the food will physically endanger you; and then there is disgust," she said.

Dr Martins' current research project is examining food neophobia in adults in a bid to develop techniques to reduce it. Her research is using university student volunteers to identify and evaluate responses to a range of familiar and less familiar foods prepared in her kitchen-laboratory.

Dr Martins said that distaste traditionally has been regarded as the chief reason behind food neophobia.

"What I have found in my research, which seems to be converging with other research overseas, is that disgust is playing a significant role in the rejection of food, and that what seems to be underlying the disgust response are perceptions of the food's texture," she said.

Disgust poses a major problem in reducing food neophobia: while it is usually possible to persuade adults and even children to try food they initially reject on the basis of distaste or danger, it is very difficult to find successful strategies to overcome disgust, Dr Martins said.

"When people have a problem with texture, or at least their perception of texture, it is much more resistant to change," she said.

This may be because disgust is a basic or core emotion, Dr Martins said. Disgust is universally accompanied by a facial expression in which tongue pokes out in a mimic of retching, and a behavioural response of distancing oneself from the offending substance.

"From an evolutionary standpoint, if you ate something that might be bad for you, it would have evoked the disgust response, which would have caused the food to fall out of your mouth so you wouldn't ingest this toxic or dangerous thing," Dr Martins said.

In later life, disgust acquires a cognitive aspect, so that the basic emotional and physiological response develops a moral dimension, reflected in revulsion towards acts such as incest or violence.

"It is a very strong emotion," Dr Martins said.

Disgust towards food also can be bound by cultural factors, but these are learned rather than intrinsic. Dr Martins said researchers in the field formerly believed that food derived from animals was more likely to produce disgust, but the idea no longer holds sway.

"We now have evidence that disgust can be exhibited to non-animal foods just as strongly," she said

"Basically what we're seeing is rejection of the thought of eating a food on the basis of what it is, where it comes from, or its social history."

And with the "what it is" aspect, it seems texture is almost entirely to blame. "Overwhelmingly, when you pin people down about what they dislike about the food, they come up with a negative textural sensory property - they think it's slimy or it's gelatinous, it's got a mouth feel they don't like," Dr Martins said.

"Tomatoes, mushrooms and onions are the three most rejected non-animal foods in children.

"And it's something that is really hard to change in adults, and really hard to change in kids."

Dr Martins said parental concern over picky eating in their children was frequently unnecessary.

"It could well be a developmental phase like any other, and in the end children will eat when they get hungry."

Dr Martins said little research on food rejection had been undertaken in Australia.

"I am aiming to see if the factors that underlie disgust are similar to those in other parts of the world - I have no reason to believe they won't be, but you have to be sure," she said.

"If the studies show the problem to be textural, texture will become the target, and we will see if exposing people to varying textures can help them overcome these reactions."