A new study from the Proceedings of the National Academy of Sciences confirms what many confused shoppers, dieters, and investors know first-hand: when a decision is difficult, we go with the status quo or choose to do nothing.

(The last time I tried to buy a new printer online should have been proof enough for me; after hours of analyzing features, prices, and customer reviews, I gave up. It's a miracle I'm not still using a dot-matrix printer with the hole-threaded, rip-off margins.)

Ahem. Back to the science: Researchers from the Wellcome Trust Centre for Neuroimaging at University College London created a computerized task. Participants viewed a series of visual tests that asked them to play a referee making a sports call (e. ., whether a tennis ball bounced in our out of bounds).

Before each test, participants were told that one of the responses (in or out) was the "default" for this round. They were asked to hold down a key while they watched. If they continued to hold down the key, they were choosing the default. If they lifted their finger, they were choosing the non-default. Importantly, the default response (in or out) switched randomly between rounds, so that a participant's response (to make a call in or out) would not be confused with their tendency to stick with the status quo.

The researchers were interested in two questions:

1) Does the difficulty of the decision influence the participants' likelihood of choosing the default?

2) Is there a signature for choosing the default vs. overriding the status quo?

As my shopping habits (and the researchers) predicted, participants were more likely to stick with the default when the decision was difficult. It didn't matter whether the default was in or out. If they couldn't make a confident choice, they essentially chose to do nothing. And as the researchers point out, this tendency led to more errors.

What was happening in the participants' brains as they chose? The researchers observed an interesting pattern when participants went against the default in a difficult decision. There was increased activity in, and increased connectivity between, two regions: the prefrontal cortex (PFC) and an area of the midbrain called the subthalamic nucleus (STN). The PFC is well-known to be involved in decision-making and . The STN is thought to be important for motivating action.

The researcher's analyses couldn't determine for sure what the relationship between the PFC and STN was, but the observations were consistent with the idea that the PFC was driving, or boosting, activity in the STN.

These brain analyses suggest that going against the default in difficult decisions requires some kind of extra or . Otherwise, the decider in our mind is puzzled, and the doer in our mind is paralyzed.

Knowing this can help explain why changing habits can be so difficult. If you aren't sure why you're changing, don't fully believe you're making the right choice, or question whether what you're doing will work, you're likely to settle back on your automatic behaviors. That's why -the belief that you can make a change and overcome obstacles-is one of the best predictors of successful change. The decider and the doer need a boost of confidence.

It also helps explain why we love formulaic diets, investment strategies, and other decision aids. Formulas feel scientific, tested, and promising. They also give us a new default. We can rely on the rules (no eating after 7 PM, automatically invest X% of your income in mutual funds twice a month) when we're feeling overwhelmed. A new automatic makes change much easier. (For more on this idea, see "The Self-Control Costs of Flexibility.")

So next time you're trying to make a change, figure out what your current default is, and remind yourself exactly why it isn't working. Then look for ways to change your default (clean out your fridge, set up direct deposit) so you don't have to fight the old default as often. And feel free to be your own cheerleader when the going gets rough. Look for the first evidence (a pound lost here, a dwindling credit card statement there) that what you're doing is paying off. The status quo is seductive, and we all need a little encouragement to lift our fingers off the keyboard.

[Printer recommendations may be left in the comments section, along with your own strategies for behavior change and decision-making.]

Study cited:

Fleming, S.M., Thomas, C.L., & Dolan, R.J. Overcoming status quo bias in the human brain. PNAS. Published online before print March 15, 2010. doi:10.1073/pnas.0910380107

Full text available here.