That's how long you have to grab someone's attention before they mentally drift off to the next thing. That's one second less than a goldfish.
Thanks to constant interruptions by smartphones and multitasking, our attention spans are getting shorter all the time.
This is also reflected in absurd investor behavior…
Over the last five decades, the average holding period for a stock has steadily declined. It's fallen from eight years to a mere four months since the 1960s. You can see this in the chart below: