Most of us are instinctively able to scan thousands of faces to recognise ones we know. But people with prosopagnosia are face-blind. It may affect one person in 50 and can be mistaken for autism. Now psychologists at Carnegie Mellon University, in the US, are working on high-tech aids to help people who, because of their genes, can’t recognise faces.

They plan to give patients the face-recognition computer programs being introduced by UK police to compare CCTV footage against photographs of hundreds of thousands of criminals. Marleen Behrmann, a psychologist, says: “We are also designing programs that could train patients to improve their recognition skills.” Many prosopagnosics cope by looking for distinctive hairlines, beards or eyebrows.

The team reports in Trends In Cognitive Sciences how MRI scans show, oddly, that when people with the condition see faces, the same regions of their brains light up as in normal people. Unravelling this mystery still presents a “large challenge,” says Behrmann.

Diet-faddy toddlers

JAMIE OLIVER might have the Government on the run over school lunches but a nutrition scientist has a cautionary word for food-conscious parents: toddlers can get dietary deficiencies by sharing your healthy low-fat diets.

Judy Driskell’s study of pre-school-age children in the town of Lincoln, Nebraska, found that two thirds of them were deficient in levels of vitamin E.

“Parents are eating a lot of low-fat and non-fat products and we are finding that they also give their children such things as skimmed milk,” says Driskell, of the US Institute of Agriculture and Natural Resources. Some dietary fat is needed for the fat-soluble vitamin E to be absorbed.

In a report from the University of Nebraska, she recommends that children regularly consume whole milk, as well as nuts and seeds and wholegrain cereals fortified with vitamins.

Message muddle

CONSUMER researchers have discovered another way in which healthy food messages can backfire — people get in a muddle over product warnings.

A study in the Journal of Consumer Research asked 64 people to read positive health messages and told them they were false. But three days afterwards, people increasingly remembered the messages as positive ones.

This paradox is called the “Illusion of truth effect”, as Carolyn Yoon, a researcher at Michican University, explains: “If, for example, an ad campaign falsely promised that a herbal supplement reduced arthritis pains, a typical warning would tell consumers, ‘It is not true that taking the supplement will reduce your arthritis pain.’

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