Related: growing up, one of the things that my sister and I would joke about was the extent to which we both would both unconsciously smell our wrists and lower

Related: growing up, one of the things that my sister and I would joke about was the extent to which we both would both unconsciously smell our wrists and lower arm areas while doing math. We would catch each other all the time doing it and it was hilarious. Here is an example of what I am talking about: https://static01.nyt.com/images/2016/03/24/business/24artificial1/24artificial1-superJumbo.jpg https://static01.nyt.com/images/2016/03/24/business/24artifi... As a completely uninformed guess, I think the link between focus and smelling one's hand/wrist might have something to do with early feelings of comfort as an infant associated with the smell of a parent's skin. The idea being that introducing a close approximation of that smell would remove any distraction brought on by other, less familiar smells, and increase focus.