Since the First World War, the United States has distributed chewing gum to military personnel to help them strengthen their concentration and relieve stress, and several studies have confirmed that chewing gum can improve performance for jobs that require visual memory and auditory memory.
It is not clear why the chewing gum has such a role. One of the possible reasons is that the chewing action helps stimulate blood flow to the brain, but there are experiments that require the subject to have nothing in his mouth but pretend to chew. The result is not the same.
In addition, the action of the tongue and the sputum that allows the chewing gum to move around in the mouth will cause frequent movements in certain parts of the brain, and those brain regions may be distracted if they are not active.