After a while your brain makes sense of the patterns and knows they are lights attached to two people.

Your brain is very good at recognising patterns. Everyday you see people move, dance and run and now you can recognise each of these actions from seeing  the movement of just 12 points on the body.

However, you can’t recognise them from a stationary picture because there is not enough information for your brain to make a ‘best guess’.

Cartoonists know this, and use only a few lines to show the expression or identity of their characters.