Perception of Flavor: A Basic Primer on Cross-Modal Interactions

Hello, readers!  I’m going to diverge from my usual m.o and present today a slightly older study than I usually do.  Instead of being published in the last year, this one was published in 2017.  Why? Well, I’m in the beginning stages of a new project on perception of taste and flavor and am reading a whole bunch of papers from a wide range of years.  Today’s paper I consider to be a short, introductory paper to the general topic of interest for this new project.  Nothing earth-shattering to be found here, but could be interesting (to at least some of you) nonetheless.

“Last sip of wine” by paulaloe is licensed under CC BY 2.0

You all are familiar with the basic list of human senses:  sight, smell, sound, taste, and touch.   You touch an ice cube and you feel cold.  You look at a stop sign and you see an octagonal shape that is red and white (unless you’re colorblind, but I digress).  Each of these senses are independent modalities that when activated “talk” to the brain to provide it with some knowledge into what it is that is being perceived. 

Of course, like most things in life, there is often “cross talk” or “cross-modality” that can occur, particularly when it comes to activities like eating or drinking (or tasting wine!).  In other words, when you are tasting wine, you aren’t just utilizing your sense of taste, but also your sense of smell.  Additionally, you could be engaging your sense of sight as well if you’re looking at the color of the wine or perhaps the wine bottle itself.  This interaction between senses during wine tasting or other gustatory adventures is what we all call “flavor”.  Flavor is the result of multiple independent modalities working in concert to craft and define how we perceive the wine (or whatever) to be.

A 2017 Italian study in the International Journal of Bioelectromagnetism aimed to introduce this concept of cross-modality interactions in wine tasting by examining subjects tasting wine with and without the use of their nose. 

In a nutshell, participants were novice wine drinkers who tasted two Italian wines (Sangiovese and Morellino di Scansano) in an “open nose” and “closed nose” situation.  For the “closed nose” condition, participants wore a nose clip.  For open nose, participants tasted the wine like they would any other time.

Participants were also hooked up to this highly fashionable headpiece that consisted of an EEG band as well as autonomic sensors on the fingers.

“Cerebral appreciation” via the “Approach Withdrawal Index” was evaluated by using the EEG data, since studies have shown there to be a relationship between the EEG frontal asymmetry theory and emotional responses.  In other words, the EEG data taken during the wine tasting might give clues to the participants’ emotional state during that time.  A greater value would indicate a more “approachable”/”accessible”/”overall positive liking” emotional state, while a lower and more negative value would indicate a more “withdrawn”/”overall disliking” emotional state.

Blood volume pulse and galvanic skin responses were evaluated using the finger sensors mentioned above.  These variables may also play a role in human state of emotion.

The results of the tasting suggested that the open nose condition tended to elicit a more approachable emotional response from the participants compared with the closed nose condition.  In other words, participants enjoyed the wine more when they had use of their nose compared to when their nose was closed and not usable.  It is important to note that this result was just a trend – the results were not statistically significant due to some high variability in the open nose condition.  The researchers suggested this lack of statistical significance could be related to the fact that participants were novices with very little wine knowledge, but I suppose the only way to know for sure is to run the study again with wine experts.

The results were significant for the emotional index, however.  Open nose tasting yielded significantly higher emotional index scores than the closed nose tasting.

In general, this study gives a primer into how two independent sensory modalities may work together to influence perception of flavor in wine.  In other words, the results indicated that when the participant had use of both their nose and mouth, they were more satisfied with the perceived flavor and experience from an emotional standpoint.  When they no longer had the ability to smell, overall satisfaction or appreciation of the same wines decreased.

This post is just the tip of the iceberg of what is to come of this project I’ve begun working on.  Stay tuned!

Source:

Cartocci, G., Cherubino, P., Modica, E., Rossi, D., Trettel, A., and Babiloni, F. 2017. Wine tasting: a neurophysiological measure of taste and olfaction interaction in the experience. International Journal of Bioelectromagnetism 19(1): 18-24.

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