Neuroscientists disagree.
In "Cool: How the Brain's Hidden Quest for Cool Drives Our Economy and Shapes Our World," Steven Quartz and Anette Asp explain that there are three "pleasure machines" which drive every purchase you make.
1. 'Survival' compels you to seize the item in front of you.
The instinct that keeps you alive also has the unfortunate consequence of leading to expensive impulse purchases - especially in the case of food.
Quartz and Asp cite a study performed by Caltech researchers, who placed snacks in front of participants and asked what they'd be willing to pay for them.
For comparison, they showed the participants a picture or said the name of the snack - for instance, "potato chips."
People were willing to pay 40-60% more when the snack was right in front of them, because seeing food triggered a survival response that told them to buy (and eat) it.
In fact, the survival pleasure machine isn't the only one that comes into play when you're face-to-face with something delicious. Learn about the psychological biases that influence how you experience the grocery store.
2. 'Habit' coerces you to buy what you're used to.
"The Habit pleasure machine works by valuing actions instead of their outcomes," Quartz and Asp write. Take your morning coffee, for example: if you had an awful cup this morning, that doesn't mean that you won't crave coffee tomorrow when you wake up. In fact, you might work in an office with terrible free coffee, and still keep on drinking it.
That's because it's the habit that your brain values, not the experience of drinking coffee. So if you're trying to save money by giving up Starbucks, you may have to work hard to make it stick. Try these tips to build new habits that will help you save money, not spend it.
3. 'Goals' tempt you to get lost in the details.
This part of your brain helps you act rationally and make smart decisions, but can also slow you down. "At the supermarket, your Goal pleasure machine is the one that has made a list at home and then deliberately seeks those items within your budget," Quartz and Asp explain. "But if you've ever grocery shopped with someone who takes ten minutes to decide on what kind of salad dressing to get - muttering on and on about the pros and cons of various types and brands - you've seen the Goal pleasure machine in action."
Knowing that your brain controls your purchasing decisions in ways you don't expect doesn't mean that your conscious mind is off the hook entirely. It never hurts to take a look at your spending choices and see if there are any unnecessary expenditures that you can cut. Or read about at the habits of people who are in complete control of their spending - they'll give you the inspiration to stay focused on your goals in the future.