As a parallel example, consider the computational problem posed by a bus stop. If there is a live display saying that the next bus is “arriving in 10 minutes,” then you get to decide once whether to wait, rather than taking the bus’s continued not-coming as a stream of inferential evidence, moment by moment, and having to redecide and redecide. Moreover, you can take your attention away from squinting down the road—spinning—for those ten minutes straight.