According to this popular science article, on most people read a social media article for 15 seconds or less, and watch a video for 10 seconds or less. I tried to go down the link rabbit hole, but failed to find any concrete studies- only more pop sci and blog posts.
Really, I am interested in the psychological aspects of processing news on social media sites. Much of fake news propagated on social media exploits that we make very quick decisions as to whether to believe/ follow up what we read on social media, such as by using figures that seem reasonable- they exploit our 'type 1', heuristic reasoning. I would be grateful if someone could provide references to further studies- whether simply providing statistical data like the average time spent reading a post, or ones trying to unpick psychological mechanisms of processing this news.