Using a brain scan, naturally:
Every shopping decision is an emotional tug-of-war, as the pleasure of getting something new competes with the pain of spending money… When subjects were first exposed to the item, a part of the brain called the nucleus accumbens (NAcc) was turned on… When the subjects were exposed to the cost of the product, the insula was activated… If the insula’s negativity exceeded the positive feelings generated by the NAcc, then the subject almost always chose not to buy the item… However, if the NAcc was more active than the insula, the object proved irresistible.
Study here [gated, but with abstract].
Fascinating.
Demonstrating yet again that mental phenomena have a parallel reflection in physical phenomena. Perhaps what we call “mental” is only an illusion, and at base, everything is really physical.