The conscientious group ("introverts") had lower levels of inflammation, which is an immune response. Inflammation can also be caused by stress. It's a lot mo

The conscientious group ("introverts") had lower levels of inflammation, which is an immune response. Inflammation can also be caused by stress. It's a lot more plausible that the conscientious group is just less stressed. The researchers likely invented the immune hypothesis in order to tie in with another study showing the same immune/extrovert link.