The brain simply isn't wired to absorb information in two simultaneous forms as well as it takes in one type of information. Processing the written and spoken word at the same time creates quite a challenge for the mind, according to John Sweller, a researcher from the University of New South Wales.
"PowerPoint presentations can backfire if the information on the screen is the same as that which is verbalized because the audience's attention will be split between the two," he said in a statement released through the university.
Sweller crafted the Cognitive Load Theory, which deals with the amount of information people can process at once. Sweller believes it's more difficult to process language and retain new information simultaneously.
What really tunes the brain out during PowerPoint? Speaking the same words that are on the screen, according to Sweller.
Edward Tufte, a Yale researcher and professor emeritus, also concluded that PowerPoint weakens verbal and spatial reasoning and corrupts statistical analysis.
Not surprisingly, Microsoft lists many benefits from PowerPoint, including faster presentations.