Feeling blue? Then forget retail therapy as you'll make the wrong purchases

We all know, in our heart of hearts, that retail therapy is a bad way of dealing with the blues. Now scientists have discovered just how costly it can be.

They claim that depression makes us pay four times as much for something as we would when cheerful.

Even a few hours of sadness is enough to turn shoppers from canny to careless.

Researchers showed two teams of volunteers different videos. One, of Australia's Great Barrier Reef, was "emotionally neutral".

The other was a sad clip about the death of a teacher a little boy idolised.

Then they took the test subjects shopping, asking them to make an offer of what they were willing to pay for various items.

The group who had watched the sad video offered to pay £1.05 for a bottle of water - more than four times as much as the 25p the group who'd seen the nature video offered, says the study to be presented to a meeting of the Society for Social and Personality Psychology in Boston.

The researchers, from Harvard, Carnegie Mellon, Stanford and Pittsburgh universities, also asked volunteers to write essays about how they thought a sad situation such as the one in the video would affect them.

They found that the sadder people were, the more self-focused they became, using I, me, my and myself much more in their essays. The more they used those words, the more willing they were to spend money.

The researchers concluded that sadness can trigger a chain of emotions leading to extravagance.

Sadness leads people to become more focused on themselves, causing them to feel that they and their possessions are worth little.

That feeling increases their willingness to pay more, in an attempt to feel better about themselves.

But the researchers also discovered that the sad subjects had no idea that their video had had such a dramatic effect on them.

Harvard Professor Jennifer Lerner, who studies emotion and decision-making, said: "This is a phenomenon that occurs without awareness.

"It goes several steps beyond simple retail therapy where people know they are gloomy and want to cheer themselves up.

"Our sad test subjects did not realise they were feeling depressed. They had no idea this was going on."

Clinical psychologist Edward Charlesworth, of Houston, Texas, said: "The advertising industry latched on to this phenomenon decades ago without understanding the mechanics of it.

"Think how many advertisements tell you to buy things to feel good, or because you deserve a break, or because you're worth it."

Personal shoppers, who make a business of prowling the aisles for others, say they frequently see clients stray from their budgets when they're feeling blue.

"At that point, cost isn't usually a factor," said Kalyn Johnson, of New York City-based Style by Kalyn Johnson.

"They say, 'If I can have these wonderful shoes, I'll look better, and feel better'."