We can define prejudice as a prior image we have of something or someone, the action of supporting or opposing a particular person or thing in an unfair way, because allowing personal, irrational and often unconscious opinions to influence us.

They create expectations in us that our mind strives to match to reality.

We already spoke about how our intense expectations can change reality  and now we want to see how much a prejudice or bias can determine our beliefs without our realizing it.

Nothing can help us understand better than a practical example, seemingly trivial but actually truly surprising.

The prejudice experiment

If you were asked what determines the quality of a wine, what would you answer? The type of grapes? The soil on which the vineyard is located? The weather?

No, none of these.  Do you know what the most important aspect is? The price tag!

Surely now you’re smiling and you think it’s a bit superficial statement, suitable only for abstainers who can’t recognize a good wine from a cheap one. Then read carefully what happened during this experiment and you’ll change your mind.

The experiment worked like this. The participants were allowed to taste five wines, all Cabernet Sauvignon, on which was shown a label with these prices: 5 10, 35, 45, 90 dollars. At the end of the tasting they were asked to express their preference.

At this point, the researchers analyzed the results and found that the most expensive bottles were the most appreciated. “Of course”, you’ll say. But it’s not quite what it looks like.

An incredible turn of events

Of course our experiment concealed a trick! The wines that the unsuspecting participants were tasting were not five but only three, the same wine had been presented with the label of 10 and 90 dollars, the same thing for the bottle of 5 and 45 dollars, which contained the same wine.

So, when the participants said they preferred wine with a $ 90 label over wine with a $ 10 label, they were actually evaluating the same wine!

And now we have to ask ourselves a question: why?

First, we have to recognize for those who are not a true connoisseur that it is difficult to give a precise evaluation of the quality of a wine. Therefore it is likely that the subjects involved in the experiment have been helped by a “cognitive shortcut”,  the price indicated by the label that at that time seemed to be a valid reference.

Or they might have wanted to be smart to choose to indicate the most expensive wine as the best wine thinking of making a better impression and passing for connoisseurs.

And here comes another surprising element.

Also the brain has been deceived!

To make sure that the participants’ response was sincere, the researchers decided to interview their neurons directly.

With the help of a very sophisticated machine called Functional Magnetic Resonance Imaging, they scanned the blood flow of the brain with an MRI scan, moment by moment, through the production of color images that indicate which areas are directly involved. Depending on which circuits you switch on, which neural connections you trigger, you can know exactly what happens in the brain at any given time.

The result clearly showed a different activity of some areas of the brain in relation not to the different wines but to the different labels that had been attached to the wine. In particular during the tasting of wines labeled  as tastier, regardless of whether they really were or not, was recorded a greater activity of the left part of the cortex medial frontal orbital, an area responsible for the processing of the experience of the pleasure deriving from the smells and the flavors.

 What are prejudices for

A prejudice is a mental pattern, a generalization, created by our culture, the context in which we live, our experiences, to which our brain makes use in order to save time. It allows us to simplify situations by referring them to examples that we already know, so that we can classify them in no time.

Often it happens, however, that these patterns are applied incorrectly and it happens to be a bit too ready to give explanations of things for which we don’t really have an explanation. And we can even fool our brains. We generate beliefs based on inadequate assumptions and we are not able to recognize the error.

This prevents us from seeing reality and it prevents us from fully living experiences.


Prejudices often deceive us by making us see an altered reality. But how can we fix prejudices? The first step is to become aware of their existence and their power, the second is to start questioning our opinion and ourself.

Once again we thank the Italian psychologist, Davide Lo Presti that in his book “The self-fulfilling prophecy” (“La profezia che si autorealizza”, in the original Italian title)  his demonstrations gives us valuable suggestions on how not to fall into the trap of our prejudices.

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