In the study, appropriately titled, "Cognitive advantages of chewing gum. Now you see them, now you don't," a group of participants was directed to chew gum before taking a "battery of cognitive tasks," while others chewed the gum during the tests. Their performances were compared to a control group of gum-less participants. The results were surprising: those who smacked on the gum five minutes before the tests received a short, 15-20 minute mental spurt. Those who chewed the gum during the exercise, and those who did not chew any gum at all, received no comparable benefit.
The researchers speculate that it was less the gum and more the act of chewing itself - "mastication-induced arousal" - that was the reason for the boost. Gizmodo helpfully translates: "The act of chewing, in other words, wakes us up, ensuring that we are fully focused on the task at hand." The benefits, however, were short-lived, and the researchers speculate that your brain, like an old computer, is too slow to multitask effectively: "The lack of improvement in cognitive function when gum is chewed throughout testing may be because of interference effects due to a sharing of resources by cognitive and masticatory processes."
This information naturally lends itself to any number of practical applications. For tests that start easy and progessively become more difficult, for example, you might want to start chewing as you bubble your way through the middle portion of the Scantron. Or start chewing right before oral arguments and before clicking on the first slide of your Powerpoint presentation. Just remember to heed your high school teacher's admonitions and dispose of that gum properly - no amount of mental boosting will make it any easier to get gum off your shoe.