"Consumers don't base their spending behaviour on their hopes and fears," he says.
When cards were introduced, there was little in the way of theory to suggest how they would influence spending behaviour.
His 2003 paper, The Realities of Spending, looked at models of spending behaviour and how they were influenced by means of payment.
Obviously, the world has changed in the past decade; the recession affected consumers' spending behaviour, and the internet has forced brands to be more transparent and accountable.
It began: "It has been known for some time that the specific payment mechanism used by consumers has a significant effect on spending behaviour.
"The banks are brilliantly set up for this, they monitor your spending behaviour and their computers know immediately if something isn't right, or are alerted if the additional security questions aren't answered correctly," she said.
One idea is to tap into a phone's GPS system, a bit like the way banks use location data to spot payments and cash withdrawals being made in places that fall outside a customer's typical spending behaviour.
These will test whether people with distinctly different spending behaviour, such as miserliness and extravagance, experience different amounts of pain (or, at least, show different patterns of brain activity) in response to prices.
A rich variety of household-level data sources (such as the Consumer Expenditure Survey conducted by the U.S. government) allows economists to examine household spending behaviour in minute detail, and microeconomists have also utilized these data to examine interactions between consumption and other microeconomic behaviour such as job seeking or educational attainment.
In their model, the hypothetical household had to decide both the likelihood of a potential catastrophe and its magnitude, since a high-risk disaster with little consequence would affect spending behaviour differently to a rare but devastating event.The model has the disadvantage of being, like many economic models, theoretical.
