Reference: Ammann, J., Stucki, M., & Siegrist, M. (2020). True colours: Advantages and challenges of virtual reality in a sensory science experiment on the influence of colour on flavour identification. Food Quality and Preference, 86, 103998.

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Think of the last time you ate an apple. What did it taste like? Although you might think that your taste perception is primarily influenced by the molecules interacting with your tongue, sensory science research suggests that your taste is influenced by your other senses as well. In fact, the appearance of food plays an important role in food selection and how its flavor is perceived. 

In researching the factors that influence flavor perception, sensory scientists have used beverages as stimuli because color is easier to change in liquid products than in solid products. That is, scientists can easily turn liquids into specific shades using food coloring, but this is much more difficult to do with solid foods. Up until now, scientific knowledge has been somewhat limited by this element of the experimental design.

This is where technology comes in handy! In particular, virtual reality (VR) – computer-generated environments that appear to be real – allow for even solid foods to appear in different colors quite easily.

Does visual perception influence taste perception in VR environments?

Researchers Jeanine Ammann, Michelle Stucki, and Michael Siegrist of ETH Zurich’s Department of Health Science and Technology designed a study to find out. Specifically, the researchers conducted two experiments to investigate whether a sensory science experiment in real life could be transferred to a VR environment. 

In the study, participants wore a headset that covered their eyes, but not their noses or mouths so they were able to eat and drink with the headset on. The headset projected images – the virtual reality environment – into their line of sight. The researchers also used a Leap Motion controller that tracked participants’ hand movements and projected them through the headset.

While wearing the VR headset, participants consumed three food products in a randomized order: orange juice, grape juice, and lemon cake. The food products were digitally modelled through the VR headset. A random half of the time, participants saw the food product in its original color (e.g., orange juice displayed in the color orange) – this was the control condition. The other half of the time, participants saw the food product in a modified color (e.g., orange juice in the color green) – this was the experimental condition. In between consuming each food product, participants drank some water to cleanse their palate. 

After consuming each food product individually, participants were asked to identify the dominant flavors that they tasted (i.e., the flavor that stood out the most). 

In a second study, the researchers used a similar protocol, but with the addition of a control group that consumed the cake and juices in a “real-life” (RL) environment – that is, without the VR headset. In this RL group, a random half of the time, participants saw the food product in its original color, and the other half of the time, researchers manually changed the color of the food products using dyes (i.e., the experimental condition). The researchers also replaced the grape juice with pineapple juice given yellow was an easier color to modify with food coloring in real life. 

This design allowed the researchers to directly compare real-life and VR environments, which can inform how useful they are for studying taste perception.

Real life and virtual reality environments found comparable results

In both virtual reality and real-life environments, participants were less likely to correctly identify the flavors of the food products when the color of the food was modified (either digitally or through the use of food coloring). For example, when consuming the lemon cake that was modified to appear brownish, many participants reported tasting chocolate. These results replicate previous sensory science studies in real-life environments, suggesting that the appearance of food plays a critical role in taste perception! 

Applying VR environments to sensory science research

Most importantly, the fact that similar results were found in the real-life and virtual reality environments suggests that VR has exciting applications in sensory science moving forward. The researchers mention that VR might be especially useful for market research in the food industry. For example, food companies are often interested in whether customers can taste the difference between various formulations of a food product, but want to hold other environmental features (e.g., the way a product looks) constant. VR environments allow for this possibility and much more!