Jonah Lehrer displays the cognitive benefits of gum:

The act of chewing … wakes us up, ensuring that we are fully focused on the task at hand. Unfortunately, this boost is fleeting. The takeaway of this research is straightforward: When taking a test, save the gum for the hardest part, or for those questions when you feel your focus flagging. The gum will help you concentrate, but the help won’t last long.

(Photo: "Sugar Free," a plaster bust covered with sugar-free gum, by Nick van Woert via Today and Tomorrow)