This graphic, based on data from Lumen Research, shows that only a few media are able to hold viewers' attention for more than about 2-3 seconds (on average). If the advertising objective is simply to show/say something that quickly reminds people of what they already like about the brand, this short dwell time is not an issue. However, if the goal is for the advertising to create new brand memories that make people interested in the brand in the first place, channels like TV, YouTube and magazines provide an opportunity to tell a longer story that is more likely to be retained in long-term memory and influence purchase decisions for months or even years to come.

See 'The Challenge of Attention' for more details.