'No smoking' signs increase nicotine cravings, says study

'No smoking' signs may be driving more people to light up, a psychological study suggests.

Scientists say the messages have an "ironic effect" on smokers that increases their craving for tobacco.

Without being aware of it, they react to the signs by thinking of and wanting cigarettes.

"You get ironic effects when you couple information that people perceive with negation," said researcher Brian Earp, from Oxford University.

"When I say don't think of a pink elephant, I've just put the thought of a pink elephant in your head.

"A lot of public health messages are framed in a negative way: say no to drugs, don't drink and drive, no smoking.

"No smoking signs in particular are everywhere. If you're a smoker walking down a street you're likely to pass five or six of these signs in windows or on doors. If you have a chronically positive attitude to smoking this could boost your craving."

To test the theory, Mr Earp's team first primed a group of smoking volunteers from a town in New England, US, by showing them a number of photographs.

Some included a no smoking sign in the background or at the edge of the picture, while others had the signs edited out.

Next, the same volunteers took part in a "joystick test" looking at their reactions to a series of screen images.

The technique is widely used to assess instinctive tendencies to embrace or avoid certain stimuli.

Moving the joystick away is associated with avoidance, while drawing it towards the body indicates a desire to bring the stimulus closer.

In a series of experiments, the researchers showed that participants who had earlier been shown no smoking signs were more drawn to smoking-related images such as ash trays and cigarettes.

"It's a significant effect which we think would have real life implications," said Mr Earp, who presented the findings today at the British Psychological Society's annual meeting in Glasgow.

Follow-up research which has not yet been published indicates that anti-smoking messages really do prompt smokers to light up.

Mr Earp thought the same principle might apply to other public health messages, such as "say no to drugs".

He added: "What's interesting is the ironic effect of the negative image. No smoking signs are meant to discourage an activity but what happens is you get a kick back so that the very item that's supposed to be prohibited becomes more desirable.

"My hunch is that having all this 'don't do this' information out there may have ironic consequences."

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