An example of a great psychological idea: the single best improvement in passenger satisfaction on the London Underground, per pound spent, came when they didn't add any extra trains, nor change the frequency of the trains; they put dot matrix display boards on the platforms -- because the nature of a wait is not just dependent on its numerical quality, its duration, but on the level of uncertainty you experience during that wait.
Et eksempel på en stor psykologisk ide: Den bedste forbedring i passager tilfredshed i metroen i London per pund, kom ikke da de tilføjede ekstra toge eller ændrede hyppigheden på togene, de satte prikmatrix display tavler på perronerne. Fordi ventetidens karakter ikke kun er afhængig dens numeriske kvalitet, dens varighed, men graden af usikkerhed man oplever, imens man venter.