Decision bias: Study compares energy drinks to alcohol and drugs

By Nikki Hancocks

- Last updated on GMT

Getty | Energy drinks
Getty | Energy drinks

Related tags Energy drink addictive

Energy drink consumers show the same biased decision-making processes often seen in people addicted to alcohol, tobacco, drugs and chocolate, say researchers, but the amount they drink does not reduce through cognitive modification techniques.

'Attentional bias' describes when a person is affected by recurring thoughts making them less likely to consider alternative possibilities and 'approach bias' describes when a person has a tendency to approach a specific stimuli.

Both biases have been demonstrated for a range of appetitive substances, including alcohol​, tobacco​, drugs​, and chocolate​ and just a handful of studies have also shown an attentional bias for caffeine​. 

Studies have shown that both biases can be manipulated through targeted training, known as cognitive bias modification, by training individuals to avoid appetitive stimuli by diverting their attention or making avoidance movements. Such effects have been reported for alcohol​, tobacco​ and chocolate​. In addition, there is some evidence that a reduction in bias can produce a corresponding reduction in consumption. However, many studies have not found any effect of cognitive bias modification on consumption.

Therefore researchers from Flinders University in Australia decided to carry out a study to discover if energy drink consumers show these biases for energy drinks.

Their two investigations conclude that regular energy drink consumers show both an attentional bias and approach bias for energy drink cues. 

They also found for the first time that biased processing of energy drink cues can be manipulated through targeted training, just as has been shown for other substances, in particular, alcohol​, tobacco​ and chocolate​. However, they found that this did not lead to a lower intake of energy drinks.

“The main focus of the current study was to examine biased decision-making processes as a possible contributing factor to energy drink consumption,”​ the report states.

“Our finding that regular energy drink consumers show both an attentional and an approach bias for energy drink cues adds energy drinks to the list of substances for which cognitive biases have been shown, including alcohol, tobacco, drugs and chocolate.

"The popularity of energy drinks is likely due to their high levels of caffeine. Although a handful of studies have shown an attentional bias for caffeine in coffee drinkers, none have as yet demonstrated an approach bias.”

Experiment 1

Paticipants were 116 (69 women; 18–25 years) 'regular energy drink consumers' (consuming energy drinks at least once per fortnight).

A dot probe task​ was used to measure and manipulate attentional bias for energy drink cues. Stimuli consisted of digital photographs of cans of energy drinks and non-caffeinated soft drinks.

Energy drink intake was assessed by a taste test in which participants were presented with the two most popular energy drinks, Red Bull and Mother, and two popular soft drinks, Sprite and Solo.

Participants tasted each drink and rated it on several dimensions sweetness, fizziness, and likeability. Participants could sample as much of each beverage as they wished.

Energy drink consumption habits were assessed by a brief questionnaire. Participants reported how often they consume energy drinks,  the average number of energy drinks they consume in a day, the maximum number of energy drinks they ever consumed on any one day, their preferred energy drink brand, and their main reasons for consuming energy drinks.

The findings of Experiment 1 demonstrated for the first time an attentional bias for energy drink cues in regular energy drink consumers and that it can be altered.

Attentional bias modification eliminated the initial attentional bias but this was not accompanied by a lower intake of energy drinks in the taste test.

Experiment 2 

Participants were 110 regular energy drink consumers (76 women; 18–28 years).

The approach-avoidance task​ was used to measure and manipulate approach bias for energy drinks. 

To determine an approach bias for energy drink cues, researchers compared response times of trials in which participants pulled the joystick in response to energy drinks pictures with those in which participants pushed the joystick in response to such pictures in the pre-training phase.

Incorrect responses and outlying response times were eliminated. Participants were faster to pull than to push the joystick in response to energy drink pictures, indicative of an approach bias for energy drinks. A similar analysis showed an approach bias for soft drinks too.

The researchers say the observed approach bias to both energy drink and soft drink cues are not necessarily mutually exclusive.

"Research shows that individuals who consume energy drinks often also consume soft drinks​," the report states. 

"Second, the nature of the approach-avoidance task makes it is possible for participants to demonstrate an approach bias for both the target and the control stimulus categories, as on each trial participants are presented with, and respond to, a single stimulus. By contrast, in the dot probe (attentional bias) task the target and control stimuli are paired and compared directly within trials."

To examine the effect of the approach-avoidance training, researchers compared response times to energy drink pictures at post-training with those at pre-training. 

The findings of Experiment 2 demonstrated the existence of an approach bias for energy drink cues (as well as soft drink cues) in regular energy drink consumers. Furthermore, approach bias modification, like attentional bias modification, eliminated the initial approach bias in the avoid group.

However, in line with Experiment 1, approach bias modification did not have a significant effect on energy drink consumption in the taste test. However, results were in the expected direction in that energy drink intake in the avoid group was lower than in the approach group.

Further research

The authors note that future studies will need to determine whether energy drink consumers show attentional and approach biases for energy drinks because of the addictive properties of caffeine.

No different to other caffeine sources

In response, British Soft Drinks Association Director General Gavin Partington, said: “The European Food Safety Authority confirms the safety of energy drinks and their ingredients and, therefore, does not provide any scientific justification to treat energy drinks any differently to the main contributors to daily caffeine intake including tea, coffee and chocolate. It is worth remembering that coffees from popular high-street chains contain the same or more caffeine than most energy drinks.

“Energy drinks are legally required to declare ‘High Caffeine Content. Not recommended for children or pregnant or breast-feeding women’ followed by the exact caffeine content expressed in mg per 100ml on the label. The BSDA Code of Practice on energy drinks was introduced by and for our members in 2010 and contains a number of points on responsible marketing.”


Source: PLoS ONE

Kemps. E., et al

Cognitive bias modification for energy drink cues.

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