A study by researchers at the University of Warwick and Cardiff University has found that money only makes people happier if it improves their social rank. The researchers found that simply being highly paid wasn't enough – to be happy, people must perceive themselves as being more highly paid than their friends and work colleagues.
The researchers were seeking to explain why people in rich nations have not become any happier on average over the last 40 years even though economic growth has led to substantial increases in average incomes.