Is it better to focus time and energy on one project to generate leads and new business? Or will you see more results by dividing your time and energy among 10 different projects to enhance your marketing? Did you know that multitasking doesn’t actually increase productivity? The more projects we start and the more marketing we throw out there, often the less productive we become.

With multitasking in general, the thought is that because we are so busy, we must do more than one thing at a time to accomplish the growing list of activities that pull on our limited time. The facts prove, however, that although we feel we are getting more done, we are actually causing ourselves more work. Here are a few studies that may surprise you about how multitasking actually has a negative effect on productivity (and may even make you less intelligent).

When we multitask, (i.e., try to perform two or more related tasks at the same time or by alternating rapidly among them) errors greatly increase. That is according to a study done by David Meyer of The Brain, Cognition and Action Laboratory at the University of Michigan. Meyer and his team found that it actually takes far longer to get jobs done this way than if the tasks were done sequentially.

A Harvard Business Review article from 2010 claims that multitasking leads to as much as a 40 percent drop in productivity, increased stress and a 10 percent drop in IQ. Now that’s scary! And a 2009 study at Stanford University looked at 100 students who multitasked during the day, juggling various forms of technology, the Internet, school work, classes, etc. What they found was that the more the students multitasked, the worse they performed on the tasks they were attempting.

Today the average attention span is 17 seconds, and that means that no one is paying attention to anyone or anything for very long. Let’s bring back our focus, and I bet we could also see an increase in desired results, especially in our marketing. This will not be an easy task; distraction and multitasking have become standard operating procedure. So, what can you do to change that?

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Maribeth Kuzmeski is the founder of Red Zone Marketing, LLC, which consults to Fortune 500 firms on strategic marketing planning and business growth. For more information, go to www.redzonemarketing.com.