That ability to look at the brain while it processes decisions about issues such as equity and risk is providing new insights not only for economics, but also for neuroscience, psychology, and even philosophy.

"This is about a very specific subset of moral decisions," Hsu said. "This goes back to a lot of the political philosophers who talk about how we allocate burdens and benefits in a society. In formal terms it's called distributive justice. There are a lot of theories about how we should do this, and our study comes from an economic approach. We study that within the context of individual decision-making."

Neuroeconomics as a branch of behavioral economics investigates biological and neural processes as people make decisions about purchasing, investing, or bargaining. And Ming is a young researcher at the forefront of this developing field. While at Caltech, he was lead author on a paper about the Ellsberg Paradox, Neural Systems Responding to Degrees of Uncertainty in Human Decision-Making that was published in Science in 2005 and he has done a paper about the experiment with the children's home for Science in 2008. Although he uses technology like fMRI and views topics through the lens of neuro-science, Hsu said his field of neuroeconomics fits within traditional economics.

"Right now what we've done is coming from a very traditional economic perspective," Hsu said. "I think only a really hardcore rational choice economist would be surprised by that. I think it's just filling in the picture. The interesting things are things we never thought about before like the connection between inequity and risk."

Those connections are at the heart of the neuroscience aspect of Hsu's research. The headscanner measured blood flow during both the children's home experiment and the study about the Ellsberg Paradox, illuminating which brain regions are activated when people are asked to make those kinds of decisions.

"We found basically that the classical decision regions are very much involved in this type of decision making," Hsu said. "In the past people haven't really found that. We found in the striatal regions in the dorsal striatum that encode equity and efficiency, the more money you give to these kids and the more equitable it is, the more these regions fire. These regions are the ones that are activated when you get money personally. Rats are happy when cocaine is injected into these regions.

"One of the emotional regions in the brain, the insula, responds to inequities, so the more inequity that the subjects are able to save with their choices, the more this region fires. It's almost as if this region is pushing you toward making the more equitable choice. The difference between subjects' activation of the insula have in other studies been found to correlate with their level of risk-aversion."

Hsu said issues of equity and risk are connected in the brain.

"You can relate equity sensitivity or moral sensitivity to brain function," he said. "Both inequity and risk have very deep theoretical connections. With those you are essentially comparing distribution. If you think of a financial market, it's a distribution of returns that you are worrying about when it comes to risk. With equity you are caring about the distribution of, say, income or education or whatever variable you want to measure in a population."

Any investigation that could shine a light as to why people make economic decisions would, needless to say, be of interest to those concerned with finances and investments. In addition to the Wall Street Journal the work of Hsu and his colleagues has been written about in Forbes and the Chicago Tribune. His initial project using fMRI, which resulted in the paper on the Ellsberg Paradox, had ramifications for financial planning.

"The basic idea is that there are different types of uncertainty in the world," Hsu said. "In classical theory of uncertainty you have some probability distribution over some event, and you use that information. The classic counter argument is the Ellsberg Paradox."

Hsu said most people in the coin flip experiment usually choose the unbiased coin, even though the odds are the same as with a biased coin (again assuming you don't know the bias) as a balanced coin. The Ellsberg Paradox experiment tested what brain regions fired when people were evaluating ambiguous gambles versus risky gambles where the probability is known.