While it is commonly known that smokers feel cravings and have physiological reactions to pictures they associate with smoking, a new study shows that a smoker's cravings can also be trained to non-smoking related stimuli.

Much like Pavlov's dogs salivating in response to hearing the bell they associate with dinner time, people experience classical conditioning experiments that link a neutral stimulus, such as a sound or a picture, to an event, like eating or smoking.

After comparing the reactions of smokers and non-smokers to a smoking related picture or to a neutral, non-smoking related picture researchers Marianne Littel and Prof Franken from the Erasmus University Rotterdam found that smoking captured everyone’s attention, despite being a smoker or not.

The classical responses of the participants were later paired to a second round of neutral stimuli, which was a geometric shape, a cube or a pyramid and their cravings and electroencephalography (EEG) measurements of brain activity were recorded at each stage.

The authors explained that, for both smokers and non-smokers, EEG results showed that P3 brain waves, thought to be involved in attention are bigger for the shape paired with smoking related stimulus (CS2s) than to the shape paired with non-smoking related cues (CS2n).

"All our participants had greater second order conditioning for smoking-related cues than the neutral cues, showing how smoking captures everyone's attention. However for the smokers only this training was related to feelings of craving and pleasure," said Littel.

While the smokers had larger P3 waves for CS2s than non-smokers Littel said that this suggests “smokers also have an enhanced ability for drug-related 'associative learning' compared to non-addicts.”

“When the experiment was continued the differences between smokers/non-smokers were lost. This may indicate that second order conditioning is transient or simply that the participants lost interest and concentration."