Putting the Fun into Fungibility

My apologies for my recent silence, I've been working hard on my MSc dissertation (now successfully finished). The topic of my dissertation was 'fungibility'. My next few posts will explore fungibility and why being aware of it may help you make more rational decisions.

Fungibility is the principle whereby economic agents treat all units of money as equal and as perfect
substitutes, regardless of where they came from.

Violations of fungibility occur when individuals use money differently because of the way it was earned, stored or labelled. Violations of fungibility can cause us to make suboptimal decisions and are thus termed irrational.

Take the example of an €8 gift voucher at an expensive restaurant. For some customers the voucher can be spent on beverages (the 'labelled' voucher) while for others the voucher can be spent on either food or beverages (the 'unlabelled' voucher). As almost all customers spend at least €8 on beverages the gift is 'nondistortionary'.

Johannes Abeler and Felix Marklein (2013) ran this field experiment and found that customers who had the labelled voucher spent on average €3.90 more on beverages than those with the unlabelled voucher.

The label attached to the money had changed behaviour (even though, rationally speaking, both groups should have spent the same amount on beverages as the voucher was nondistortionary). This 'labelling effect' violates the principle of fungibility.

So the next time you receive a labelled voucher think to yourself 'Would I have spent that much on ... anyway?' 'How much was I originally prepared to spend on ...?'

It might just help you avoid be more rational in how you spend your money.