How not to play Poker

Demonstrating that behavioural economists are no more rational than anyone else I committed the same mistake playing poker that I did about a year ago...

I acted irrationally by seeing different colour chips as qualitatively different as well as quantitatively different. Despite the fact that one black chip was worth five white chips, I preferred betting five white chips than one black chip because I saw the higher value black chips as in some way better. This led me to be more risk averse when I had lost my white chips and had only black chips to bet.

Because I saw equivalent amounts of money as different I acted in a non-fungible manner. I'm not blaming this violation of fungibility for my poor performance (I lost, badly) but I am surprised to see myself commit the exact same mistake that I even wrote a blog about before. Some people never learn...

The Disposition Effect

A person who has not made peace with his losses is likely to accept gambles that would be unacceptable to him otherwise.

(Kahneman and Tversky, 1979) 

Stock brokers prefer to sell stocks that rise in price than stocks that fall in price. The preference for 'winners' over 'losers' is driven only by the desire to realise gains over losses. This is called the disposition effect, and it is likely to lead to lower profits.

This is because attitude to risk is different for losses than gains. Behavioural economics has shown that people tend to be risk seeking when it comes to losses, but risk averse when it comes to gains. For example, a stock that depreciates in value will be seen as a loss, making the stock broker more risk seeking and therefore more likely not to sell it (it may go up in value again). But if the stock rises in value then the stock broker is more risk averse and therefore more likely to sell it (to avoid the risk of it falling in value).

The disposition effect increases taxable income (Odean, 1998). If stock brokers realise 'winners' they have to pay tax on the gain. But stock brokers do not have to pay tax on 'losers'. Thus stock brokers could put off paying tax (and thus earn money) by holding 'winners' for longer. And by selling 'losers' taxable income reduces; if stock brokers sell the 'losers' and buy almost identical stocks taxable income actually falls. Thus the disposition effect is irrational for stock brokers (but good for the Inland Revenue!).

The disposition effect is a violation of fungibility because investors view units of money either side of the gain/loss boundary as qualitatively different. This is an example of non-fungibility causing market failure. If investors were aware of this non-fungibility they might be less likely to exhibit it.

Temptation

The neoclassical economics way of viewing people involves assuming that people are fully capable of making the best decisions for themselves. If a neoclassical economist were to see someone (lets call him Nick) blowing all their savings in a Las Vegas casino he would simply assume that Nick had done all the sums and had concluded that his own personal benefit was maximised by gambling his life savings away.

That may be the case.

But behavioural economists tend to think not.

What if Nick knows what is best for him but chooses not to do it?

What if Nick has finite powers of self-control?

What if Nick hasn't even done the sums properly? He might be aware it's not the best option for him, but not just how disastrous it is.

Behavioural economists use the term 'bounded rationality' to refer to instances where people are clearly less than perfect (often by their own admission). If Nick may overly value short term fun over long term welfare. He knows he's being irrational, but he might need a helping hand to maximise his long term welfare. This is why people are increasingly offered commitment devices - in a rare moment of clear thinking Nick could opt into a scheme which bans him from casinos.

Corporate decision making can also fall foul of self-control issues. A timely example is the over-fishing of EU waters. If politicians really had the long term welfare of fishermen (and of the fish!) in mind then they would restrict the amount of fish that can be caught.