A field experiment at LHR

At Heathrow Terminal 2, there is an escalator and a lift to take you from the Underground up to departures. The authorities have put a sign up:

TIME ON ESCALATOR 3 MINUTES

TIME ON LIFT 58 SECONDS

TAKE THE QUICK ROUTE – TAKE THE LIFT

Why has this happened?

1. Standard economics: the sign was a mistake. People already choose the optimal route. (Public choice theory: the sign was not a mistake but a deliberate conspiracy by the elevator company to wear out the lift and make money from replacements.)
2. Social preferences: the sign is a nudge to counter travellers' "lift aversion".
3. Social norms: there is a norm of taking the escalator. People really want to take the lift, but they are afraid what others will think of them.
4. Social heuristics: people mistakenly assume the escalator is faster, as it usually is in their experience. The sign corrects this.

This is a biased choice of example. In other situations, the first three explanations might be more plausible. Still, many lab experiments might be cases of 4, mistaken for cases of 2 or 3.

I first read the term "social heuristics" in this paper.