Baroness Julia Neuberger at the West London Synagogue. Photograph: Sophia Evans for the ObserverEver since her appointment a year ago to head the House of Lords inquiry into behavioural change, Baroness (Julia) Neuberger has noticed that her grocery shopping habits have altered. "I've been looking at the labels very closely," she says. "Takes much longer. The usual thing of throwing it all into the trolley – no!"
The labels that Neuberger has been examining with such intent are designed to provide customers with colour-coded guidance on the amounts of salt, sugar and fat within each product. It is hoped that by using the "traffic light" system to highlight the more harmful ingredients, in say, a chocolate Hobnob, members of the public will be persuaded to eat more healthily.
It is an example of "nudge", the belief, promulgated by two American professors in a 2008 book, that human beings can be encouraged to make life-improving choices through incentives and social cues rather than through regulation and government legislation.
The theory – outlined by Richard Thaler, professor of economics and behavioural science at Chicago Graduate School of Business, and by Harvard law professor Cass Sunstein – has been eagerly adopted by David Cameron, who set up a behavioural insight team last October. The unit was charged with introducing nudge to the "big society" or, as the coalition agreement puts it, "finding intelligent ways to encourage people to make better choices for themselves".
It was hoped issues such as the obesity crisis could be tackled by nudges – clearer food labelling, placing fruit not chocolate near supermarket checkouts – rather than by heavy-handed (and expensive) state intervention.
The problem, as Neuberger saw it, was that there was "precious little" evidence to show that nudge worked beyond a purely individual basis. So the Lords set up a subgroup of its respected science and technology committee to examine the issues. After 12 months of research, 148 written submissions and evidence from 70 witnesses, the report will be published on Tuesday. It will make uncomfortable reading for Cameron because, according to Neuberger, nudging people is not normally enough.
"Basically you need more than just nudge," she says, when we meet in the Lords. "Behavioural change interventions appear to work best when they're part of a package of regulation and fiscal measures," she adds, putting down her papers and a large canvas bag from Daunt Books in Hampstead. She notices me looking at the bag. "I use it for everything! I don't like briefcases."
The difficulty with nudge theory, she says, is that "all politicians love quick fixes. I mean, they look at very short time frames. I think one of the problems with all of this is if you really want to change people's behaviour it takes a very long time … you have to look at a 20- to 25-year span before you get a full change of behaviour."
As an example, Neuberger points to the efforts to persuade people to wear seat belts in the 1970s, which incorporated an advertising campaign and legislation. "So it was a whole series of measures that did eventually change the climate." Later, she adds: "I think politicians would be well advised to use these sorts of behavioural interventions as part of an armoury."
"Politicians all have a split personality," she adds. "On one level, they engage their brains and they know perfectly well that things do take quite a long time to happen. On the other, they've got a very short time frame: they want to get re-elected, they need to make a mark. They have been, I think, very persuaded by the work of Richard Thaler and Cass Sunstein. I think they found that very appealing because, broadly, they prefer the idea of using behavioural change interventions to legislating or using fiscal measures."
Presumably, part of the appeal is also that, in a time of austerity, nudging costs much less than legislating? Neuberger nods. "There needs to be a huge amount of work, which I think the government will eventually have to pay for."
Did she enjoy Nudge when she read it? "It's quite engaging," she replies, not entirely enthusiastically. "It's quite compelling as a book but, like all of those sorts of book – like The Tipping Point, like Bowling Alone, those books that have made quite an impact on politicians – I would say, you want to stand back for a few minutes and say: 'But, but, but'."
From September, Neuberger will become a full-time rabbi at the West London Synagogue and going on to the crossbenches. "Because I've got members of the congregation of all religious faiths and none, I don't want people to think I'm preaching Lib Dem politics from the pulpit."
She has clearly enjoyed heading the select committee – "it's been a fantastically good experience" – but there is one thing she won't miss. "There was a huge amount of written evidence," she says, holding her hands at least 10 inches apart. "I mean, it's like that – absolutely vast. It's been with me backwards and forwards to Leamington Spa [where she lives with her husband, Anthony], but it always has to go in the car because it's just too much to lug about." She pauses, then adds with an impish grin: "Even in my Daunts bag."
Properly funded, graduate interns could lead the big society. Photograph: Christopher Furlong/Getty