Sour tastes make people push the boundaries

Experiencing a sour taste in the mouth is strongly linked to risk-taking behaviour, a new study shows.

In a paper published in the journal Scientific Reports, computer scientists Chi Thanh Vi and Marianna Obrist of the University of Sussex, UK, report on the first ever two-nation experiment to determine the relationship between the five basic tastes – sweet, bitter, sour, salty, and umami – and doing nail-biting things.

The researchers used two cohorts of adult volunteers, one in the UK and the other in Vietnam, and conducted an elegantly designed (and harmless) experiment.

At the heart of it was a standardised, computer-based, gambling exercise called the Balloon Analogue Risk-Taking (BART) task. It involves an animated balloon which each player “inflates” by repeatedly pressing the left-button of a computer mouse. As the balloon grows larger, winnable reward money increases.

Players can cash-out at any stage by pressing the right-button. However, if they choose to continue pressing the left one, building their potential winnings, they risk the balloon exploding, with the consequent loss of the lot.

Vi and Obrist gave their volunteers a series of drinks, each one containing one of the five tastes or neutral-tasting water, in a random order. After each glass, they were asked to play the BART game. Every volunteer ran through the drinks and game-playing routine twice.

The researchers found that among the UK cohort, the sour taste was very strongly linked to rapid and aggressive mouse-clicking – with the number of pumps per balloon between 16 and 40% higher than those made after consuming sweet, salty, bitter or umami drinks.

The same pattern held for the rate of clicking, except in the case of post-sweet gameplay, which was as frantic as the sour cases.

Vi and Obrist then repeated their experiment in Vietnam, reasoning that the country’s love of monosodium glutamate – a powerful umami taste – might affect the reaction to sour tastes. Not so, it turned out. There were differences between click-rates and risky behaviour in relation to the other basic tastes, but, yet again, sour drinks prompted a clear boost in aggressive balloon-pumping.

The findings, say, the researchers, may open therapeutic avenues for using food to treat personality disorders.

“Knowing that sour promotes a riskier behaviour, it allows us to explore suggestions to either promote or inhibit risk-taking behaviour through employing a sour-reduced or sour-enriched diet,” they conclude.

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