The Sensation and the Perception of Color: two words with Prof. Alessandro Rizzi

Interview with Alessandro Rizzi, Full Professor at the University of Milan – Department of Informatics – Head of the MIPS Laboratory. Presidential Advisor of the Color Group.

Color does not exist in nature, it is formed in our brain through a stimulus coming from outside and produces in us a certain sensation that is completely different from that perceived by any other animal. There is also a philosophical aspect according to which everyone perceives color as something absolute and extremely personal. In practice, everyone has their own filter towards reality, but the ability to discriminate color is essentially the same for everyone. The intersubjective variance referred to visual perception, color in particular, is very low: we all see the world more or less the same way. We talk about it today with Prof. Alessandro Rizzi, one of the greatest experts in the world of color.

GA: Prof. Rizzi, what is the main factor that influences hair colors? And how does the perception of color in the human brain “work” on a chemical level?

AR: The answer to the first question is simple: light. In the field of Beauty this becomes the most interesting key. The question of the more or less good hairdresser is given by the training of his brain that processes the information captured by the eye.

At the base, however, there is the sensation – which is our ability to discriminate colors; above this is developed the perception – further processing of our brain that also considers our experience, the interpretation of the scene, our education and profession.

Parallel to the musical field, a note corresponds to the frequency of oscillation of an instrument; a frequency of light, on the other hand, does not necessarily give exactly that color: it is something more elaborated and mediated in the brain, it is something much more complex.

A complex cortical processing such as the generation of the sensation of color has connections with many things, starting from a very recent discovery: the circadian cycle (read that regulates the alternation wake-sleep of our body, controlled by some ganglionic cells. The latter transmit the visual signals acquired by cones and rods, but are also influenced by sunlight that hits the lower part of the retina and transmit this additional information to the system that regulates the circadian cycle. The deep neurological aspects related to the perception of color are still to be discovered …

GA: Let’s talk about color in the salon. Why is it so difficult to create the really correct shade when making a hair dye?

AR: Cosmetics in general is a very important field of application for colour: the hair is a fantastic example. On colour spaces, additivity, subtraction, pigment mixing, etc. we find all the literature on hairdresser training: but then there is a huge gap between the “measured” colour – the one for which instrumental measurement is given – and the final result. The chromatic and aesthetic value of the hair does not or differs greatly from the average colour: it goes without saying that this colour is difficult to measure and must be analysed in context, passing from what we can define as “chromatic appearance”.

Appearance is the result of our visual system on the spatial – as well as spectral – distribution of what is observed. If I observe a simple flat colour, it will deviate a little from the measured colour; if I observe a hair, I see it rich in reflections and minimal chromatic differences with phenomena of scattering, chaotic bounces of light energy. 

The difficulty in measuring hair colour has made dyeing it an art and the best yardstick for classifying a hairdresser.

Visual inspection by experienced personnel remains the most reliable approach to date, assisted by light as close to natural light as possible.

This statement is the result of scientific research published in the authoritative journal COLORATION TECHNOLOGY.

GA: Is there a correlation between the choice of a colour and the emotional/emotional state of the person who requests it?

AR: Colour reveals a very strong emotional component: it is our sensory reaction.

There’s a lot to read about the relationship between colour and emotions, maybe even too much. Many of the things written on the subject are vague and contradictory. This does not mean that the relationship does not exist, but it is proof that describing or simplifying it is not easy. 

Who has gone further in describing this relationship is perhaps Max Lüscher, a Swiss sociological psychotherapist and philosopher (see). Already in 1949 he had developed a psychological test of the projective type that bears his name and is based on the choice of certain colours: with this test he shows that by prioritising certain carefully chosen colours we stimulate a particular emotional response and reveal our inner world.

The answer is therefore yes: colour speaks about us and influences us, perhaps it even frightens us a little: there is a revolutionary aspect to its ability to stimulate profound responses. Colour can transmit a lot on a conscious and unconscious level: it talks about people and makes people talk… 


As we understood from our conversation with Prof. Rizzi, the nature of colour is much more than just the physical aspect of the stimulus that enters the eye. 

In my book La Cosmetica Umanistica – to be published on October 22nd – you will find further information about it and a very interesting in-depth study – written by Prof. Rizzi together with Dr. Angelo Moretti – that explains the “mechanics” of colour. 

The text takes place in the form of a dialogue as in the ancient literary traditions and features Physis <; the physical aspect of the chromatic signal, and Perceptum <; the result of the complex processing carried out by the brain, the final appearance of colour. Do not fail to read it!

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