Sunday, June 17, 2018

Citric Acid Increases Balloon Inflation (aka sour taste makes you more risky)

from Balloon Analog Risk Task (BART) – Joggle Research for iPad

Risk taking and risk preference1 are complex constructs measured by self-report questionnaires (“propensity”), laboratory tasks, and the frequency of real-life behaviors (smoking, alcohol use, etc).  A recent mega-study of 1507 healthy adults by Frey et al. (2017) measured risk preference using six questionnaires (and their subscales), eight behavioral tasks, and six frequency measures of real-life behavior.

Table 1 (Frey et al., 2017). Risk-taking measures used in the Basel-Berlin Risk Study.

-- click on image for a larger view --

The authors were interested in whether they could extract a general factor of risk preference (R), analogous to the general factor of intelligence (g). They used a bifactor model to account for the general factor as well as specific, orthogonal factors (seven in this case). The differing measures above are often used interchangeably and called “risk”, but the general factor R only...
...explained substantial variance across propensity measures and frequency measures of risky activities but did not generalize to behavioral measures. Moreover, there was only one specific factor that captured common variance across behavioral measures, specifically, choices among different types of risky lotteries (F7). Beyond the variance accounted for by R, the remaining six factors captured specific variance associated with health risk taking (F1), financial risk taking (F2), recreational risk taking (F3), impulsivity (F4), traffic risk taking (F5), and risk taking at work (F6).

In other words, the behavioral tasks didn't explain R at all, and most of them didn't even explain common variance across the tasks themselves (F7 below).

Fig. 2 (Frey et al., 2017). Bifactor model with all risk-taking measures, grouped by measurement tradition. BART is outlined in red.

Here's where we come to the recent study on “risk” and taste. The headlines were either misleading (A Sour Taste in Your Mouth Means You’re More Likely to Take Risks) or downright false no lemons were used (When Life Gives You Lemons, You Take More Risks) and this doozy (The Fruit That Helps You Take Risks – May Help Depressed And Anxious).

To assess risk-tasking, Vi and Obrist (2018) administered the Balloon Analog Risk Task (BART) to 70 participants in the UK and 71 in Vietnam. They were randomly assigned to one of five taste groups [yes, n=14 each] of Bitter (caffeine), Salty (sodium chloride), Sour (citric acid), Umami (MSG), and Sweet (sugar, presumably). They were given two rounds of BART and consumed 20 ml of flavored drink or plain water before each (in counterbalanced order).

[Remember that BART didn't load on a general factor of risk-taking, nor did it capture common variance across behavioral tasks.]

As in the animation above (and a video made by the authors)2, the participant “inflates” a virtual balloon via mouse click until they either stop and win a monetary reward, or else they pop the balloon and lose money. The number of clicks (pumps) indicates risk-taking behavior. Overall, the Vietnamese students (all recruited from the School of Biotechnology and Food Technology at Hanoi University) appeared to be riskier than the UK students (but I don't know if this was tested directly). The main finding was that both groups clicked more after drinking citric acid than the other solutions.

Why would this this balloon pumping be more vigorous after tasting a sour solution? We could also ask, why were the Vietnamese subjects more risk-averse after drinking salt water, and riskier (relative to UK subjects) after drinking sugar water?3 We simply don't know the answer to any of these questions, but the authors weren't shy about extrapolating to clinical populations:
For example, people who are risk-averse (e.g., people with anxiety disorders or depression) may benefit from a sour additive in their diet.

Smelling lemon oil is relaxing, but tasting citric acid promotes risk:
Prior work has, for instance, shown that in cases of psychiatric disorders such as depression, anxiety, or stress-related disorders the use of lemon oils proved efficient and was further demonstrated to reduce stress. While lemon and sour are not the same, they share common properties that can be further investigated with respect to risk-taking.

We're really not sure how any of this works. The authors offered many more analyses in the Supplementary Materials, but they didn't help explain the results. Although the sour finding was interesting and observed cross culturally, would it replicate using groups larger than n=14?


1 From Frey et al. (2017):
The term “risk” refers to properties of the world, yet without a clear agreement on its definition, which has ranged from probability, chance, outcome variance, expected values, undesirable events, danger, losses, to uncertainties. People’s responses to those properties, on the other hand, are typically described as their “risk preference.”

2 The video conveniently starts by illustrating risk as skydiving, which bears no relation to being an adventurous eater.

3 The group difference in umami had a cultural explanation.


Frey R, Pedroni A, Mata R, Rieskamp J, Hertwig R. (2017). Risk preference shares the psychometric structure of major psychological traits. Science Advances 3(10):e1701381.

Vi CT, Obrist M. (2018). Sour promotes risk-taking: an investigation into the effect of taste on risk-taking behaviour in humans. Scientific Reports 8(1):7987.

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