Gustatory Illusions & Cognitive Collusion

Look at the below optical illusion. How many black dots can you find? At the very bottom of this post is the answer. Read on for an explanation, as well as an experiment with taste that you can try at home.

This illusion is designed to illustrate the participatory process of the brain in vision perception. We typically think of our senses as a one-way street — objective reality goes in through the eyes (or ears, fingers, nose or mouth) — and what we perceive is an accurate reflection of that reality. However, notice how your perception of this image changes as you count.

What is happening? Your brain is participating in the creation of your mental representation of the image by incorporating expectation effects. In this particular vision hack, the intersecting lines create the expectation that there is no black dot, and your brain, unless you are looking directly at a black dot, imposes this expectation on your mental representation of the image! The result is dots that appear and disappear seemingly at random. We don’t often think of reality as being variable, but in fact what we often call “real” is a moving target.

Gustatory Illusions

The participation of your brain in the creation of your personal reality goes beyond vision — gustation and olfaction also incorporate expectation effects! Further, unless we manipulate the effect to ‘prove’ it, we don’t know it is even happening — what we perceive is our personal reality, which is unique from everyone else’s in the world. It is common experiences that drive common versions of reality.

In the world of sensory science, which is the science of taste, smell and how consumers make choices based on sensory input (e.g. taste tests), we typically survey 50–100 people or so and ask questions, and often we try to ‘remove’ these participatory effects by controlling the environment — the idea being that by controlling expectation, we can isolate our taste test to the product variables we are interested in. More often than not, this can be a pretty bad way to do research, because these participatory effects are more deeply rooted in perception than most of us believe, and the human experience with participatory sensory effects may bear little semblance to what we really care about, which is the consumer’s experience with a particular food product in their natural environment.

For example, one particular method involves training people for hundreds of hours on specific tastes and flavors to turn the human into a finely calibrated instrument. There are hundreds or thousands of these calibrated panels all over the world and they are widely used to inform flavor decisions of products. These panels are used not to describe likes and dislikes, but to describe the sensory properties — e.g. in coffee, the amount of roasted notes, blueberry notes or bitterness. For us to believe these panels are useful, we must believe that they can objectively describe a common reality. A valid question, though, is what is the relevance of a description of a sensory experience that doesn’t include expectation effects? Is it showing us some “truth”? Or is it simply describing a specific version of reality that may not resemble our own? And if the latter, whose reality are we biased for and against?

The below experiment is the “taste” version of the optical illusion above and is designed to be a fun and easy project to do at home.

Home Taste Test Experiment

Objective: Demonstrate the role of Expectation in Flavor Perception

Supplies: vanilla yogurt, strawberry yogurt, red food coloring, 3 small bowls, spoons

Method: First, identify your blind taste tester (significant other or children work well!) and send them out of the room before you pull your supplies out. They can’t have knowledge of the preparation. Once they are removed, put 1 portion (about a half cup) of vanilla yogurt in a bowl and set aside. Put 1 portion of strawberry yogurt in each of the remaining 2 bowls. For one of the strawberry bowls, add food coloring and mix well to make it noticeably darker pink than the other one. Put all 3 bowls (2 strawberry & 1 vanilla) side by side with spoons and shuffle the order.

Bring in your blind taster. Ask them to taste each product one by one (any order) and identify the product with the strongest strawberry flavor intensity.

Discussion: More often than not the dark product will be rated as having stronger strawberry flavor, even though the only true difference is color.

We do in fact eat with our eyes — the darker color creates the expectation in our brain that the product will in fact have stronger flavor, and just like in the optical illusion above, our brain merges this expectation effect with what we are perceiving through our senses of taste and smell. This works because, in general, our worldly experience of flavor includes darker colored things having stronger flavor, so our brain is setting up this expectation.

This seems like a “trick” due to the fact we designed the experiment — however, this happens constantly in “the real world” without us realizing it. Things that we consider objective — tastes and flavors — are influenced by our own experiences.

Because there is no sensory perception without cognitive participation, what are the implications of the myth of an objective reality?

Answer to Optical Illusion

When the bottom row is isolated, you can more easily count four dots.

There are twelve dots total in the image — four each in the top, middle and bottom rows. If you still have trouble seeing it, go to the original image and cover up parts of it with a sheet of paper.

I founded MNC in order to help organizations of all sizes and stages approach consumer research, food choice and especially taste tests with the best scientific and culinary design matched with the needs of the modern, connected organization and consumer. I have numerous scientific publications and presentations but am most proud of helping bring new thinking to marketing and R&D organizations. Prior to MNC, I both matriculated and taught at the Culinary Institute of America, I led the sensory team at both a $2B FMCG organization and a small boutique market research firm, and completed a postdoc at the U.S. Army Natick Labs.