Robert Peston interprets Deborah Mattinson's report on Labour's election defeat as saying that "Labour needs to move back to the centre ground of politics, whereas Jeremy Corbyn has shifted it leftwards." This poses the question: what's so good about the centre ground?

It's not that it is a guaranteed vote-winner, as any Lib Dem will tell you. Nor is it because centrist policies are necessarily better: as I've said, centrists can be as airy-fairy utopian as extremists.

Instead, I suspect, the answer lies in something discovered (pdf) by Itamar Simonson in 1989. This is that people prefer to choose middling options. Given a range of TVs, for example, they choose neither the best not the cheapest but a mid-range one.

Good salesmen know this, and manipulate choice sets accordingly; they know that people don't follow one of the axioms of rational choice, the independence of irrelevant alternatives. In Influence, Robert Cialdini describes how an estate agent would show clients some run-down properties to make other properties for sale look good. And Dan Ariely has written:

High-priced entrees on the menu boost revenue for the restaurant - even if no one buys them. Why? Because even though people generally won't buy the most expensive dish on the menu, they will order the second most expensive dish. Thus, by creating an expensive dish, a restaurateur can lure customers into ordering the second most expensive choice (which can be cleverly engineered to deliver a higher profit margin) (Predictably Irrational, p 4)

Some new research corroborates this. Economists studied over 88,000 orders at a German restaurant, and found that mid-priced options were chosen disproportionately often.

When centrism succeeds, it does so by exploiting this compromise effect. Tony Blair and Bill Clinton did this brilliantly in the 90s by triangulation - rejecting both "left" and "right" and offering a middle way.

For me, this suggests there are two different types of centrism - we might call them active and passive. Wishy-washy pro-establishmentism might not work, given that so many people are cheesed off with the status quo. But more active triangulation might. And Labour can use it. To take two examples:

- "We reject the mindless austerity of Osborne but also the spending-for-spending sake of the old left. Instead, we should borrow in invest where there are payoffs to doing so - for example in flood defences, broadband and transport."

- "The old right thinks companies should be owned by ruthless tax-dodging billionaires. The old left wanted state ownership. Both have their failings. We reject both, and want more worker ownership."

I suspect that this is not what Peston had in mind: he was thinking of centrism as the same old illiterate pro-rich policies. There is, though, a different type of centrism - one which both exploits the compromise effect and has sensible economic content.