What role do our emotions play in decision-making? Some might say it's a fairly contentious one. Acting on emotions without reason can be dangerous. 17th-century French philosopher Descartes would have you believe reason trumps emotion when it comes to making decisions. But recent brain science has proven the brain is more complex than that.

Emotions, it turns out, are critical to our ability to make decisions. But understanding the role they play and why we act impulsively when we do might help with better decision-making down the line.

THERE'S SCIENCE BEHIND TRUSTING YOUR GUT

Recent research has proven that going after hunches is actually an important aspect of decision-making. Neuroscientist Antonio Damasio found that emotion is just as important as reason when it comes to decision-making. Damasio examined how people with damage to their prefrontal cortex—specifically the orbitofrontal cortex, a small region just behind the eyes that's linked to emotions and our understanding of reward and punishment—are affected in their ability to make decisions.

He found that people with damaged orbitofrontal cortexes struggled significantly when making the simplest decisions. That's because they weren't able to use their gut feeling for guidance.

That emotional pull or gut feeling that helps us make so many decisions in our lives is what Damasio calls a "somatic marker." Decisions can be made more efficiently using somatic markers rather than having to take the time to reason out every choice we make. In other words, hunches are a shortcut to good decision-making.

UNDERSTANDING IMPULSIVE THINKING

But impulsive thinking, or acting on emotions can also be dangerous because it's the default mode we often go to when making choices. According to Daniel Kahneman, who won the Noble Prize for his work on the psychology of judgment and decision-making, the brain operates under two systems: System 1 and System 2, also known as fast and slow thinking.

Fast thinking, or what Kahneman calls System 1, happens almost automatically with little effort or voluntary control. System 2, on the other hand, involves reasoning and careful consideration. "One of the tasks of System 2 is to overcome the impulses of System 1," Kahneman writes in his book, Thinking, Fast and Slow. "In other words, System 2 is in charge of self-control."

FORGET WHAT YOU THINK YOU KNOW ABOUT LEFT AND RIGHT BRAINS

Tempting as it may be to talk about the brain in terms of parts and what each enables us to do, neuropsychology, or the study of higher cognitive functions like thoughts, wishes, and desires, has proven the brain to be far more complex. Gone are the days of left-brain/right-brain hypotheses that had us believing each side of the brain was in charge of separate functions that don't communicate with one another.

It's just not so simple, says psychologist and neuroscientist Stephen Kosslyn. Instead he likens the way the brain works to the parts on a bicycle. "A bike has been designed to get a person from point A to point B using muscle power. It's got these parts that each respond to some input and some output, but they are all working together. That’s the key," he says. "The brain is similar. It's all a system so that the parts are designed to work together. You wouldn't want a bike where the petals weren't connected to anything."

TOP BRAIN, BOTTOM BRAIN

In his latest book, Top Brain, Bottom Brain Kosslyn takes a new approach to understanding brain function, looking at the brain in terms of top-brain and bottom-brain systems. The top-brain system uses information about the environment and emotions to help formulate a plan. The bottom-brain system organizes signals from the senses and compares them to what's been stored in the memory in order to think through the consequences.

The bottom brain classifies what's going on and sends it to the top brain, which interprets it properly. It's important for the two to work together, says Kosslyn. "If you're just being driven by top-brain, you can be a bull in a china shop where you're not paying attention to the consequences," he says. "On other hand, if you're driven by the bottom-brain, you can be lost in thought and be very passive."

FOUR COGNITIVE MODES

Kosslyn uses this top-brain/bottom-brain model to identify four cognitive modes, or default modes in thinking that we can find in people, depending on how active their top and bottom brain systems are. Those modes are:

1. Mover: is someone who uses both the top and bottom systems of the brain—enabling them to both plan and see the consequences of their actions.
2. Perceiver: tends to gravitate toward bottom-brain mode, tending to analyze and give context to a situation.
3. Stimulator: tends to make elaborate plans, but doesn't always think through consequences of those plans
4. Adaptor: is someone who doesn't overly gravitate toward either system and tends to go with the flow and let the environment or others dictate a situation.

"You can be in different modes in different contexts," says Kosslyn. "It turns out people have a default mode. All else being equal, people tend to be in one of those four modes."

HOW TO FIGHT IMPULSIVITY

Kosslyn uses these modes to unpack how we can better approach decision-making. Noticing which of these modes you fall into can help you take the right steps to balance out your own cognitive tendencies.

A Stimulator, or someone who tends to make plans without thinking through the aftermath, for example, might benefit from writing a checklist of consequences when creating a plan or collaborating with someone who tends to be more of a Perceiver. And a Perceiver who might brood on the consequences and resist making decisions, could benefit from creating a schedule of deadlines that forces action to be taken.

Just as a good leader needs a support system in place to run a company smoothly, our cognitive abilities need support to help steer us toward better decision-making, "Think about what is required to do what you need to do in a task," says Kosslyn. "It's about cognitive abilities and what you need to do certain kinds of things."