But what's even more fascinating is how the brain reacts positively to finding a bargain.

When the subject was shown the price of an affordable item in the study, the insula (the part of the brain which processes pain) initially reacted to the cost. To put it into perspective, an expensive item will cause the insula to be most active part of your brain. It's you body's way of telling you to not buy it.

But in the study, the item with a lower cost caused the medial prefrontal cortex (the rational part of the brain) to show the most activity. Researchers described it as a "hedonic competition" as it tried to decide between "between the immediate pleasure of acquisition and an equally immediate pain of paying".

"It seemed to be responsive not necessarily to price alone, or how much I like it, but that comparison of the two: how much I like it compared to what you charge me for it," says Scott Rick, one of the study’s authors

In other words, the brain reacts positively not just to something you like in a shop, but specifically to the prospect of a bargain.

Another study from the University of Michigan last year found that the act of shopping made subjects feel three times less sad and up to 40 times more in control of their life than those who only browsed shelves.

“Retail therapy – shopping that is motivated by distress – is often said to be ineffective, wasteful and a dark side of consumer behaviour, but we propose that retail therapy has been viewed too negatively, and that shopping may be an effective way to minimise sadness,” researchers said at the time.

It seems that the combination of finding something you like and a bargain, really can make you happier. Pay day never looked so bright.

The psychology of shopping; why hunting down a bargain is proven to make you happier