On one side I’d like to point to Herbert Simons theory of Bounden Rationality. A good read is the Book with the same title from MIT Press, edited by Gerd Gigerenzer and Reinhard Selten.

And on the other side you could have a look at current cognitive scientists, who clearly describe intelligent processes as interactions between the brain, the body and the environment. It’s as plain as taking pen and pencil to make a calculation. (I’d recommend ‘Being There’ by Andy Clark for a read.)

By the way: remember http://www.zopa.com? Independent of Banks, and fits well in our environment, where many people have a bank account and internet access.