Natalie Haynes: How can I tell if I've been nudged?

The thing is that nudging us towards healthy behaviour may not be a very effective way of getting us to give up the Marlboro Lights, the doughnuts, and the swift gin to knock both of them back. The Coalition's policy of nudging people in the direction of healthier lifestyles, rather than using regulation, has been roundly criticised this week by the House of Lords Science and Technology Sub-Committee (which I like to assume is comprised entirely of ancient dukes and earls, gazing in bafflement at a wireless and wondering if there is a tiny man inside).

They have suggested that sometimes, a nudge away from the chips and towards the salad bar is not enough, and proposed legislation be used to ensure that, for example, traffic-light labelling appears on the food we buy. Though I would point out that this is, in essence, merely legislating the nudge: no one is proposing to ban the "red-light" foods – thank God, or I'd have to move to France to get my daily cheese fix. They're simply trying to ensure that when you buy a Camembert, you know it's not as healthy as a bag of raw carrots and a mint tea. Something which, I would additionally point out, we pretty much all knew already.

Given our natural resistance to changing our behaviour, it can come as little surprise that a government-backed nudge isn't enough to change it either. The National Blood Service has been nudging and encouraging us to donate blood for as long as I can remember. They have adverts which tell you that giving blood is doing something amazing, they tell you how many lives can be saved with a single pint, they explain that winter flu epidemics have drained their supplies. And yet still only 4 per cent of eligible donors actually donate. The remaining 96 per cent are presumably either too squeamish or too busy, or just don't want to give blood.

If that's how effective a nudging campaign is, for something which takes three afternoons a year, tops, and gives you free biscuits and lemon squash, it's no wonder that persuading people to quit smoking or exercise more isn't having a huge impact. How do you nudge someone into stopping being addicted to nicotine? If the health warnings, the expense, and the 100 per cent likelihood that a smoker knows someone who has died from smoking didn't put them off, will telling them their hair smells of fags really make any difference?