A majority of Americans have cell phones, and we are just now beginning to see the impact they are having on our lives. They can be powerful tools, but they can also be significant distractions.

I am sure all of us have noticed the people with a cell phone sometimes seem distracted. And after they answer a text or e-mail, they seem to spend a few minutes trying to recollect their thoughts before they had the interruption.

An article in Newsweek magazine documents what many of us have always suspected: there are two major drawbacks to these devices. The first is distraction overload. A study at the University of Illinois found that if an interruption takes place at a natural breakpoint, then the mental disruption is less. If it came at a less opportune time, the user experienced the “where was I?” brain lock.

A study at George Mason University found that if the distraction came during a checklist, it was easy to miss an item. Sadly, an airline crash in Madrid a few years ago was attributed to a mistake by the pilot from an interruption-induced error.

A second problem is what is called “continuous partial attention.” Cell phone users like to use their devices while they should be paying attention to something else. Psychologists tell us that we really aren’t multitasking, but rather engaging in rapid-fire switching of attention among tasks. It is inevitable they are going to miss key information if part of their focus is on their cell phone.

But another hidden drawback associated is less creativity. Looking at your cell phone when you are “doing nothing” replaces what we used to do in previous decades. Back then we called it “daydreaming.” That is when the brain often connects unrelated facts and thoughts. You have probably had some of your most creative ideas while shaving, putting on makeup, or driving. That is when your brain can be creative. Checking e-mail reduces daydreaming.

Cell phones are here to stay and are powerful tools. But we also need to know the strengths and weaknesses of the technology.