We all know that the smell of doughnuts wafting across the supermarket car park is intended to make us want to rush to the bakery section, and those samples that are handed out in the aisles are handy for promoting hard-to-shift products. However, just how effective they are at inducing customers to part with cash has been a subject of debate.

Research by Baba Shiv, a Professor of Marketing at the Stanford Graduate School of Business in California, has revealed that scents and samples could play a far more important role in influencing consumer spending than previously thought.

Professor Shiv found that eating tasty morsels whetted consumers' appetites, even when they were not hungry, driving them to seek pleasurable experiences.

This did not necessarily mean a desire to buy the sampled product, but a desire to seek out any pleasurable experience, from chocolate cake to an exotic holiday.

The finding suggests that non-food stores would do well to offer tasty inducements to customers. In one trial, students who sampled a sweet drink before watching a film not only consumed more soft drinks during the film but also indicated a stronger desire for a series of consumer goods and experiences afterwards.

Professor Shiv said: “Our speculation is that food and beverage samples activate the dopamine system in the brain, which sets into motion a general drive towards anything hedonistic, anything that yields pleasure, whether that is a massage, a dream vacation or a purely utilitarian item on sale.

In essence, anything that is rewarding for the brain. “Retailers who spray perfumes or have enticing food smells in their store seem to know instinctively the value of scent in triggering people's pleasure-seeking,” Professor Shiv said.

He also rated participants on the behaviour activation system (BAS) scale, a self-assessed measure of the tendency to “go for what one wants”.

“We hypothesised that people with high BAS measurements were probably more prone to pleasure-seeking, which has been found to correlate with activation in the dopamine systems of the brain,” he said. Pleasure-seeking after sampling was heightened in those with high BAS scores.

However, the effects of taste or odour samples do not linger: the desire to spend lasts about three to eight minutes. The implication is that customers who enjoy a chunk of cheese may reward themselves quickly by buying something luxurious, such as a scented candle, and be done with it.

Retailers, Professor Shiv suggests, may want to set up strategic sample stations to keep stimulating customers with the urge to indulge themselves.

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