People with anxiety and depression are most likely to use a shade of grey to represent their mental state.

Researchers describe the development of a colour chart, The Manchester Colour Wheel, which can be used to study people's preferred pigment in relation to their state of mind.

Peter Whorwell, professor of medicine and gastroenterology at University Hospital Manchester, worked with a team of researchers from the University of Manchester, Britain, to create an instrument that would allow people a choice of colours in response to questions.

'Colours are frequently used to describe emotions, such as being 'green with envy' or 'in the blues'. Although there is a large, often anecdotal, literature on colour preferences and the relationship of colour to mood and emotion, there has been relatively little serious research on the subject,' Whorwell said.

The researchers created a wheel of colours of various intensities, including shades of grey.

They then asked a control group of non-anxious, non-depressed people to describe which colour they felt most 'drawn to', which was their favourite and whether any of the colours represented their current mood.

When the test was repeated with anxious and depressed people, most chose the same 'drawn to' colour as the healthy participants, yellow, and the same favourite colour, blue.

When asked which colour represented their mood, however, most chose grey, unlike the healthy subjects who tended to pick a shade of yellow.

A separate group of healthy volunteers were also asked whether they associated any of the colours with positive or negative moods, according to a university release.

'When we used these results to separate colours into positive, negative and neutral groups, we found that depressed individuals showed a striking preference for negative colours compared to healthy controls,' Whorwell said.

The Colour Wheel provides a unique way of asking patients about their condition that dispenses with the need for language.

These findings were published in BMC Medical Research Methodology.