Well, recent research out of Stanford University and Carnegie Mellon sheds some light on what's going on in your brain when you are faced with the decision to purchase. It is a fight between the pleasure of getting something new and the pain of spending money.
Basically, what happens in your brain goes a little something like this. According to Jonah Lehrer, author of How We Decide:
They discovered that when subjects were first exposed to the item, a part of the brain called the nucleus accumbens (NAcc) was turned on. The NAcc is a crucial part of our dopamine reward pathway - it's typically associated with things like sex, drugs and rock 'n' roll - and the intensity of its activation was a reflection of desire for the item. If the person already owned the complete Harry Potter collection, then the NAcc didn't get too excited about the prospect of buying another copy. However, if he'd been craving a George Foreman grill, then the NAcc flooded the brain with dopamine whenever that item appeared.
But then came the price tag. When the subjects were exposed to the cost of the product, the insula was activated. The insula is associated with aversive feelings, and is triggered by things like nicotine withdrawal and pictures of people in pain. In general, we try to avoid anything that makes our insula excited. Apparently, this includes spending money.
By measuring the relative amount of activity in each brain region, the scientists could accurately predict the subjects' shopping decisions. They knew which products people would buy before the people themselves did. 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. The sting of giving up cash couldn't compete with the thrill of getting a George Foreman grill.
Apparently, stores know how to keep our NAcc fired up, yet keep the insula down. With the proposition of sales, deep discounts and the like keeping the insula in check, the NAcc can have a field day. It's like a pimp telling you his prostitutes are guaranteed to be disease free (or your money back!).
What's interesting is that, with the current state of the economy, people are not as subjective to these marketing tactics as they once were, mostly because that pesky insula is super sensitive these days. Questioning your purchases, your need for something new and the like was something we did seriously during the Buy Nothing Challenges last year. But, it's easy to slip off the buy-nothing wagon, simply because you are fighting against your own brain and a flood of dopamine.
Do you experience a "shopping high" when you buy something? Are your purchases ever tinged with buyer's remorse? Have you gotten better at questioning your decision to buy something before you purchase it or have your personal finances just made you more aware of what you are buying?
Additional reading: Shopping Centers in the Brain (from the journal, Neuron)