Editor’s note: Brain Basics from Scientific American Mind is a series of short video primers on the brain and how we feel, think and act. Below is a synopsis of the eighth video in the series written by a guest on this blog, Roni Jacobson, a science journalist based in New York City.

By Roni Jacobson

Every waking moment, you are making judgments about where to focus your attention. If you didn’t, you would be overwhelmed by the vast amount of sensory information in your surroundings. The ability to direct attention, a skill humans share with species as primitive as fruit flies, helps you process what is important to you at the moment and ignore what is not.

Two brain regions are most active when we shift our attention from one thing to another: the prefrontal cortex and the thalamus. The prefrontal cortex is involved in working memory, a mental scratchpad that temporarily holds small amounts of information. Without this scratchpad, it is hard to concentrate on anything. As the sensory relay center of the brain, the thalamus can act as a filter, separating useful information from useless background noise.

When we divide our attention between two tasks, we perform both more poorly than we would if we focused on just one of them. Talking on a cell phone while driving, for example, is dangerous because the conversation distracts you from the road, leading to more accidents. In addition, though perhaps less critically, your attempts to navigate the streets can cause you to lose track of what the other person is saying.

Thus the problem in society today is not too much information, but the misconception that people can process more than they can. You need to put away your phone in the car and turn off the television when you study, because although you may believe you’re a champion multitasker—in fact, you’re not.

Other Brain Basics videos:

Is Your Sense of Humor in Your Genes? Geneticists Crack the Code

Acts of Kindness Explained

Remember When…How Your Brain Builds A Memory

Terrified or Hopping Mad? What’s Going on Inside You

A Transformation of Light: How We See

Quick! What Is The Word for a Pair of Opposites?

The Hidden Power of Others Over You

Photo on blogs page: Courtesy of Elsie esq. via Flickr.