What's mine is mine, what's yours is ... also mine

At 21 months my boy Max still speaks largely in single syllables. "Ba" means "ball", "bath", "bottle" and somewhat surprisingly also "yoghurt". But there is one syllable that appears to have no equal and is often shouted out like some sort of primal scream: "MMMMMMMYYYYYYYY!"

Gone are the days were we can simply distract Max by dangling something shiny in front of his face while we take a toy right out of his hand. Now possession counts for everything.

Just the other day he spent half an hour lying on the couch with a copy of the book The Rosie Project (324 pages of black and white text). Every time I tried to take it off him he screamed "MMMMMMYYYYYYY!" There was nothing I could do to distract him. Nothing he would accept as an offer of exchange.

His completely irrational attachment to my book reminded me of a talk I heard a few years ago by Daniel Gilbert. His work explores why people value their possessions far more than others do … or as he eloquently describes one of the driving influences of economic decisions:

why people who own lava lamps demand more to give them up than the people who do not own lava lamps will pay to get them. Deals go unmade and storage lockers remain filled with lava lamps that are destined never again to glow.

In his study half the people were given a mug and asked how much they would sell it for, while the other half were given money and asked how much they would pay for the mug. The study showed that owners of the mugs valued them at nearly twice what the other group were willing to pay.

Based on this and other studies the authors conclude that the sheer act of "ownership" increases its perceived value.

With the recent Christmas coinciding with Max's new found understanding of ownership we have definitely entered the share-phobic phase toddlerhood – a phase that apparently extends well into adulthood.

Just a couple of days ago Max passed the next language milestone, and is starting to produce the odd two word/syllable "phrase". As he frantically repeated "MY TU … MY TU … MY TU … MY TU" I was unsure what he wanted until my daughter Susie ran up and screamed "NO MAX! IT'S MY TURN NEXT. I'M THE OLDEST!

If nothing else this new development vindicated my decision to get Max a hula hoop for Christmas … one just like his sister! He has no idea what to do with it but happily drags it around the house telling anyone that will listen that it is his.

Olivia Carter, Senior Research Fellow and Lecturer, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.