This illustration highlights how media formats vary in terms of whether they are viewed at all and if so, for how long.
For example, a 30" TV ad is only viewed by 43% of people who are in the room when the ad is playing but if they do see it, they watch it on average for about 14". A Facebook infeed ad, on the other hand, is typically seen by 81% of people but they only look at it for an average of 1.6".
This has major implications for how marketers should use these channels. TV is ideal for telling stories that go into long-term memory and make people more predisposed towards a brand whereas Facebook is better suited to triggering existing brand memories amongst people who are currently in the 'purchase window' for the category.
'Technically defined as viewable' refers to guidelines from the Media Rating Council (MRC). Whilst useful for identifying fraudulent media sales, the guidelines do not relate closely to what people actually do and don't see or for how long.
See 'The Challenge of Attention' for more details.