Marilyn's dress to Britney's gum: the science of sky-high memorabilia prices

Celebrity items tend to be relatively common artefacts yet attract phenomenal sums of money. Why?

In November last year, the dress that Marilyn Monroe wore to sing Happy Birthday to President John F Kennedy sold for $4.81 million. In 2004, several pieces of Britney Spears' used chewing gum sold for up to 100 a piece. There is even a market for the belongings of despised individuals: A bracelet Charles Manson made in prison is currently selling for $4,500.

Some of these, like Marilyn Monroe's dress, reflect a moment in history. But the attraction of others, such as Britney Spears' chewing gum, are harder to explain. Celebrity items tend to be relatively common artefacts such as clothing or furniture. Their previous ownership rarely adds any functional value and they are often indistinguishable from other, seemingly identical items in the marketplace.