Smelling With Your Eyes: How Visual Bias Affects Wine Odour Perception

sensory evaluation

During wine tasting, it’s easy enough to decide whether you like a wine or not. When it comes deciding whether the wine’s bouquet is reminiscent of gravel or puppy breath, a lot of folks would rather leave it up to the experts. While we certainly differ in our inherent ability to smell, the mechanisms behind odour identification suggest that the wine tasting playing field might be more level that we think.

Let’s put the theory to the test

Close your eyes and imagine your favourite Sauvignon blanc wine. Perhaps it has delicate green hues with fresh asparagus notes, hints of lime and a crisp acidity. If you were asked to imagine a glass of Pinotage, you might have conjured a deep red wine with the aroma of ripe dark plums, followed by smoky, mocha finish.

Reds and whites are as different as chalk and cheese…or are they?

With such wildly different aroma and taste profiles, you would imagine it to be easy to pick out the difference between a Pinotage and a Sauvignon blanc blindfolded. Yet, if asked to identify the colour of a wine solely based on what it smells like, the odds of giving a correct answer is pretty close to chance. Then why do we use such different words to describe red and white wines when we taste wine? Is it possible that we are not, in fact, describing the wine’s bouquet, but merely its colour?

It’s a matter of colour-odour congruency

We tend to describe what we smell in wine, using words of objects that are congruent with the colour of the wine. Asparagus for Sauvignon blanc, butterscotch for Chardonnay and dark plums for Pinotage. Even describing a brown hued wine as matured is congruent with our knowledge of the pigmentation changes that occur chemically during the maturation process.

In our minds, odours are seen as objects

The reason behind this phenomenon is that the process in our brain that is responsible for odour identification actually has less to do with our sense of smell than you would think. The main part of the brain that lights up during high level odour processing is the primary visual cortex which has very little to do with olfaction and everything to do with generating mental images and identifying objects. In very simple terms, our noses are fairly good at detecting a smell, but when it comes to identifying the smell, it hands over the job to our eyes. Furthermore, when we are able to see what we smell, our brains are primed to make colour congruent associations.

Don’t fire your nose just yet

The only way of getting around this very powerful perceptual illusion is to make non-visual associations with specific aromas. This principle is used during the training of descriptive sensory panels where tasters are trained to recognise specific smells without any visual cues. Even so, panellists still revert to non-colour associated imaging when describing smells such as fuzzy, flat or sticky.

The most important question is this: If your favourite Sauvignon blanc was described differently, would it be less yummy