Boosting Cognitive Performance by… Chewing?
Previous research has shown that the act of chewing gum can significantly reduce reaction times during certain tests, including numerical working memory, sustained alertness, auditory oddball, and semantic memory tasks. There are various theories about why this is the case, ranging from the activation of specific areas of the brain to improved mood and decreased stress whilst chewing, and many have hypothesized that increased activation of blood flow to the pre-frontal cortex is the cause, as both alerting and executive functions are thought to be housed there.
Alerting, orienting, and conflict resolution (executive function) are all important processes for success on the attentional network test, which requires participants to quickly make judgments that may or may not include conflicting information. Both accuracy and reaction time are recorded, and the interactions between conditions provides insight into the alerting and conflict resolution effects.
A recent study combined the attentional network test with the action of chewing gum to see what additional information neuroimaging with fMRI could add to the understanding of this strange phenomenon. Replicating previous results, the authors found that participants had shorter reaction times to stimuli while they were chewing gum than while they were not chewing.
However, they found no evidence that any behavioral effects in the alerting or conflict conditions during the test were affected, meaning that there was no trade-off between increased speed and accuracy. This suggests that an overall increase of arousal in the alerting and executive functional areas of the brain are behind the reduced reaction time. fMRI showed increased activation in the motor areas of the brain, indicating that chewing likely activates these regions first, and that these areas then increase the arousal and alertness levels during the test.
Many regions of the brain have been implicated in the effects of chewing on cognitive processing speed, but a few of them have been given more attention than the others, including the thalamus and the anterior cingulate gyrus, both of which are likely contributors to the overall alerting and arousal effects seen in these studies.
Of course, these results bring to mind many questions. Why is chewing, specifically, linked to an increase in processing speed? Do other repetitive activities have the same effect? Why does the activation of motor regions increase the level of arousal in areas that serve arousal and alerting purposes? Why is processing speed increased, but behavioral effects remain unaffected? This should be a very productive area of research in the years to come, and certainly a fun one to keep an eye on.
Hirano Y, Obata T, Takahashi H, Tachibana A, Kuroiwa D, Takahashi T, Ikehira H, & Onozuka M (2013). Effects of chewing on cognitive processing speed. Brain and cognition, 81 (3), 376-81 PMID: 23375117