How to solve ‘range anxiety’

In ‘The Adventure of Silver Blaze’, Sherlock Holmes mentions ‘the curious incident of the dog in the night-time’. ‘But the dog did nothing in the night-time,’ argues Inspector Gregory. ‘That was the curious incident,’ replies Holmes.

Along with Donald Rumsfeld’s ‘Unknown unknowns’, this is perhaps the most famous example of what you might call ‘perceptual asymmetry’. We mostly act instinctively based on what is salient, giving little thought to what is easily overlooked.

It is hence surprisingly easy to change what people do simply by changing what they pay attention to. A magnificent example of this is the London Overground, one of the most cost-effective infrastructure projects ever undertaken, though the greater part of its success was achieved not with steel and concrete, but pixels and ink. Around 95 per cent of the track had existed for a century, but it was designated as a railway, not as a Tube line.