Australasian Science Magazine

By Dyani Lewis

Doyen of the field of neuroesthetics Prof Semir Zeki explains the neuronal behaviour that underlies perceptions of ‘beauty’.

Hi I'm Dyani Lewis, thanks for joining us. What is beauty? Is there an objective way of defining what it is that makes something beautiful or is beauty truly, as the old saying goes, in the eye of the beholder? These questions were for centuries the domain of philosophers and artists evolutionary biologists since Darwin have also speculated on the question of whether there are universal features of beauty that hold true for different species.

But it's only been very recently that neurobiologists have stepped into the fray, with developments in brain imaging techniques, we can now start to ask not only what do you find beautiful. But also what actually is going on in your brain when you lay eyes on a beautiful person, or a stunning landscape painting, or when you hear a spine tingling piece of music.

To tell us about our brain on beauty, I'm joined on Up Close today by a pioneer in the field of neuroesthetics. Semir Zeki is Professor of Neuroesthetics in the Department of Cell and Developmental Biology at University College London, welcome to Up Close Semir.

SEMIR ZEKI
Thank you for having me.

DYANI LEWIS
Semir, let's start with human beauty. When we talk about how beautiful a person is, evolutionary biologists would point to certain features that make a person more or less attractive. Features that would indicate whether they are perhaps fit to father or mother our children for example. Does this mean that there are universal standards of beauty within the human species?

SEMIR ZEKI
I think there are universal standards of beauty, and maybe the easiest way of defining them is negatively. In other words I think that no one who's got eyes which are not in the sort of position normal eyes are at, would be classified as beautiful by any race or any nation. Somehow for example a man like Francis Bacon, relied on this fact, he said he wanted to give people a visual shock, and he always disfigured the faces and the bodies in such a way he was guaranteed to produce a visual shock and nobody would find it beautiful.
Now whether there is a standard of beauty which is applicable to all races, which is identical, is a somewhat more difficult question. There is no doubt in my mind that someone who is say from the United Kingdom would find somebody from Africa or Eskimo Land or China as beautiful. But there might be subtle differences which make people prefer beauty of their own race right? But I think in raw terms, there is a sort of minimal standard which has to be satisfied, for a face to be considered beautiful. And the same is true of bodies, I mean you can't possibly consider a body with, for example one arm, half the length of the other as beautiful, it won't happen.

DYANI LEWIS
So things like symmetry are important?

SEMIR ZEKI
Yes but to symmetry not as a general term, because symmetry might be important in the case of say the body, but symmetry is not necessarily considered to be a feature defining beauty in architecture. The Japanese don't especially like symmetry, they prefer asymmetry, as indeed I think do the Chinese up to a point. So that's more arguable.

DYANI LEWIS
So as soon as we move away from the human body, we get far more into the area where beauty is a very subjective phenomenon?

SEMIR ZEKI?
Well I think once we get away from what one might broadly call biological features, for example face, the body, but also landscapes. Things which say I think is beautiful, but I can't tell you why, whereas with a building you might be able to say I think this is beautiful, I can tell you because A, B, C and D.

DYANI LEWIS
Does this mean that we really can't define beauty?

SEMIR ZEKI
Well, I don't think anyone has really succeeded giving a definition of beauty which is valued across everything that's perceived as beautiful. But I think what you can do is give a definition of beauty in subjective terms. You can say I think this is beautiful and that defines it as something beautiful for you, which is not to say it necessarily defines it as beautiful for everybody. Beauty is a subjective experience, but so are many other perceptual experiences so it's not unique in being subjective.

DYANI LEWIS
Now you are interested in neurobiology of beauty perception, what kind of techniques do you use to study this, and how does that compare with how scientists might have studied beauty say 50 years ago?

SEMIR ZEKI
Well in some ways it does not differ significantly and in other ways it differs radically. It does not differ significantly in the approach which earlier people, earlier scientists, psychologists were interested in using. Just to give you a very very simple example, I draw say 10 lines of different length, how do you classify them on a scale of one to 10, do you find them beautiful or not? A psychophysical approach all right? We do that, but we go beyond and put people in scanners and ask them to classify these things again according to how beautiful they experience them to be in the scanner.
For example we take subjects and give them 300 paintings, belonging to different categories, such as faces, portraits and landscapes and abstract paintings and still lifes. Each one classifies each painting according to how beautiful they experience them to be on a scale of one to 10. Then having classified them they view them again and reclassify them, rerate them in the scanner. Then we look at the activity in their brains when they're looking at the paintings which they have rated according to beauty.

DYANI LEWIS
That activity that you see in the scanner, a functional magnetic resonance imaging or FMRI scanner, what does that activity actually represent in the brain?

SEMIR ZEKI
Well in very general terms, when cells are active, more blood is channelled to an area in which they are located and you can capture this change in blood flow. It is an indirect measure of activity and in practice it works quite well.

DYANI LEWIS
Now when people are shown a beautiful face, what neural responses do you see in their brains?

SEMIR ZEKI
Well when they view beautiful faces, you see of course activity in the visible areas, you see activities in the areas which are critical for the perception of faces, and you also see activity in a part of the emotional brain, which is known as the medial orbito-frontal cortex. The activity in the medial orbito-frontal cortex seems to correlate with the experience of beauty, and it's got a relationship. So the more intense the declared experience of beauty of a face, the more intense the activity there is. So it's quantifiable.

DYANI LEWIS
Does this then offer us perhaps a definition of what beauty is? If this area lights up, that is beauty?

SEMIR ZEKI
Well this experiment on its own does not, but if you combine it with other experiments, for example looking at beautiful faces and beautiful landscapes and beautiful still lifes, and listening to beautiful music and looking at beautiful mathematical equations. All of them, when experienced the beautiful, have as a correlate activity in the medial orbito-frontal cortex. So this tells you two things really, one is that beauty is at one level something abstract, and philosophers of these subjects have always spoken about it in the abstract.
In the sense that they don't restrict themselves to say musical beauty or poetic beauty, or they talk about in the abstract at one level. The second point is that it is quantifiable, there has been a debate in the philosophy aesthetic as to whether judgments of taste can ever be quantified, it appears that they can. And the third thing is that there is now a definition of beauty, which does not define beauty at all, but it tells you that whenever we experience something beautiful, you have as a correlate activity in the medial orbito-frontal cortex.

DYANI LEWIS
This region of the brain doesn't do other things?

SEMIR ZEKI
It is active when people have rewarding experiences or when they have pleasant experiences, but traditionally people have not been able to separate out the beautiful from the pleasant from the rewarding. Something beautiful cannot be unpleasant and it usually is rewarding in one way or another.

DYANI LEWIS
So it might be difficult then to separate it out from a rewarding experience that we get from say food or alcohol, if we're addicted to alcohol?

SEMIR ZEKI
The medial orbito-frontal cortex is actually quite a large area of cortex, and it might be possible to separate it out, there might be different groups of cells that are involved. What you require to do that, is to get the same subjects, to say look at something beautiful and then say be rewarded in a gambling task or something like that, and see whether the identical regions are active.

DYANI LEWIS
This is Up Close, I'm Dyani Lewis, and in this episode we're talking about how we perceive beauty with neurobiologist Professor Semir Zeki. Going back briefly to evolutionary biology, does the activity that you see correlate with the identification of attributes that you might describe as desirable in a mate, for example symmetry. Or is the neural activity caused by something else, like just the pure pleasure of viewing or hearing the beauty?

SEMIR ZEKI
I think Darwin would have said that sexual reflection is at the basis of beauty, and I think there's no doubt that it's an important element. Whether it's restricted to sexual selection is another matter, I doubt it. There's very beautiful plumage whose function is to camouflage right, and these are perceived as beautiful by us and I suspect also by other animals. I'll be very doubtful if this is uniquely sexual selection, I think that it has got other functions as well. May I just say one thing first, that neurobiology, unlike what people often think, does not try to define beauty. Neurobiology is really much more concerned with what are the mechanisms in the brain that allow us to experience beauty. It's a very different question.
But there are certain areas which it has studied, which raise the question of what is beauty pointed to. For example the experience of mathematical beauty, now mathematical beauty, the experience of mathematical beauty also correlates with activity in the medial orbito-frontal cortex. Mathematicians have prized beauty in mathematic formulations very very much, and according to them, not according to me, I'm not a mathematician. They would say well these are perhaps pointers, truths about the structure of the universe. Plato did regard mathematical beauty as a highest form of beauty, and I think that people like Paul Dirac would say mathematical formulations, what one should prize above all is not simplicity but beauty. Implying that if you find beauty in a mathematical formulation it is telling you something very truthful.
Now what is it telling you something truthful about? It could be two things. One would be the structure of the universe which is represented in our brains, but another aspect is the logic of the operations of the brain. This is beautiful because it is so satisfying, but is satisfying to whom and to what, satisfying to our brains. So either way it's revealing something about us and about the universe, which puts in a sense the study of beauty at a more elevated level.

DYANI LEWIS
And yet mathematical beauty is not something that is accessible to everyone by any means?

SEMIR ZEKI
Indeed, that's what makes it so interesting, see because the musical and visual beauty I've been telling you about earlier, has been studied in subjects who are largely not musicians and not artists. So it is what the common person would experience as beautiful, and by the way different people think that different paintings are beautiful. They're not all agreed on that ,but whenever they experience something as beautiful, there's a correlate activity on the medial orbito-frontal cortex.
This is not the case with mathematical beauty, here you have to have extremely extremely educated people, from a chosen culture, mathematical culture. Yet there is also a strong emotion that they feel when they experience mathematical formula as beautiful. The actability that correlates with the experience of mathematical beauty is in the same place as the activity that correlates with the experience of musical or physical beauty. Which raises the question, if you're driving experience of beauty from something which is so so specialised, what is that telling you?
May I just give you an example in an area of mathematics. String theory as I understand it, again I'm not a mathematician, but string theory as I understand it is a theory for which there is no experimental evidence. The question is would we have ever come up or would mathematicians have ever been able to come up with a theory like string theory, unless we have the kind of brain structure and brain logic that we have. This is an interesting question to address.

DYANI LEWIS
But I guess the question that I'd like to ask is, with mathematical beauty especially I guess we can acknowledge that there's a fair amount of processing going on. And even when we view an image. There's visual processing that's happening in the visual cortex or auditory processing if we're listening to music. So the medial orbito-frontal cortex, is that doing this process of judging whether something is beautiful, or is this the final point in the brain that says ah ha because of all the other processing that's gone on, now I light up and I'm active because it's beautiful, and other parts of the brain have determined it to be so?
SEMIR ZEKI
Well this is an extremely interesting question from the point of view of neurobiology. First of all you have brought in the question of judgment, and this is an extremely important issue which was raised in the philosophy of aesthetics by Immanuel Kant and others. The question is when you experience something as beautiful, it implies having made a judgement about it. So the question does the judgment come before the experience, does it come afterwards, or is it coterminous, this is not clear, and this is being studied.
So with visual stimuli or with musical stimuli or with mathematical stimuli, you are doing a lot of processing. So is there some kind of filtering in the visual areas or the auditory areas or the cognitive mathematical areas because apparently there are such areas. Is there some kind of filtering which says now this is good enough for me to send signals to the medial orbito-frontal cortex. Because the medial orbito-frontal cortex is not directly connected to the visual centres, so the question is what kind of conditions does a visual or auditory stimuli have to satisfy, in neural terms, for it to be considered experience as beautiful.
Which of course brings you to the primordial problem of to what extent are there objective qualities in the stimulus, that activate these areas in particular ways, which will then qualify them to experience as beautiful?

DYANI LEWIS
That's right, and conversely with Francis Bacon picture, are there - I don't know is there an ugliness region of our brain that gets lit up in response to those paintings?

SEMIR ZEKI
Well certainly it's similar to our experiences, ugly do correlate with activity in other parts of the brain. Whether they do so specifically with Francis Bacon paintings I don't know. But what Francis Bacon did do, and he did say, I want to give me a visual shock. What he did do, he basically disturbed, perhaps disturbed is not the correct word, he subverted, the normal representation of what the face or what the body should look like. To the extent that you could no longer consider the face as beautiful although you could consider the painting as being very painterly and masterful. The face or the body could no longer be considered beautiful.
I don't know if many people, including art critics by the way, who would say that Francis Bacon's paintings are beautiful. They're very valuable paintings, they've very important paintings, they're in an important position in the history of art and so on, but I don't think many people would call them beautiful.

DYANI LEWIS
There are things though that are perhaps not something that we might immediately think of as beautiful, but that we can learn to appreciate over time, and perhaps think of as beautiful after a while. I guess for example we might have more of an appreciation of jazz music after we've listened to it for some time. So can we train our brain to view something as beautiful?

SEMIR ZEKI
There's no doubt of that, of course we can. We're always asked, and this is in a way it's a sort of a stick to beat us with. What about culture and what about learning? Of course culture and learning are extremely important and you cannot assume that somebody who loves western music would love Chinese music and vice versa. But they must be as Clive Bell the art critic would say, there must be a skeleton that's left behind once you take all these trimmings off. See Clive Bell was quite interesting, he said that the last person, the last person to appreciate a great painting is the art historian. Because he knows too much. This is his words not mine, you want to go to savages and see what they appreciate.
So what is the skeleton which is left behind once you've taken off all the trimmings, all the cultural background, all the educational background. Is there something that's left? This is what makes it very interesting to compare the basic visual structures that you must obey to experience something that's beautiful on the one hand. What are the basic mathematical structures that you have to obey, because there you're now moving to a territory which is dependent upon learning and culture. So you've got two different sources which are so disparate in terms of the amount of cultural background required in one and none in the other. Yet they both have something in common, which is you've got certain basic rules, what are they and what do they reveal about the brain.

DYANI LEWIS
And I guess people have tried to invoke things like the golden ratio to try and explain some of these things?

SEMIR ZEKI
The golden ratio has been evoked many many times, and the golden ratio has been, I gather, quite successful in bagzilla facial surgery. But the golden ratio does not work for many other kinds of beauty, so it so rather unique. But people have been looking for basic rules, and I don't think that there is a basic rule or even a basic set of rules that applies to all that we experience as beautiful. The only rule which I think applies to everything that an individual experiences as beautiful, is a neural rule, which is that it always correlates with activity in the medial orbito-frontal cortex.

DYANI LEWIS
I'm Dyani Lewis and my guest today is Professor of Neuroesthetics Semir Zeki. We're talking about the neurobiology of beauty here on Up Close. Semir, the other thing that can very much taint our perception of beauty, and some might say very much for the better, is love. How does love influence our perception of beauty?

SEMIR ZEKI
Well I don't know that this has been specifically addressed in neurobiology, but no doubt one finds the person one loves beautiful, maybe grows to find them beautiful. But it is known that the faces of people whom we find attractive also leads to activity in the medial orbito-frontal cortex. But I suspect that there are instances of people growing to love somebody who they then find more beautiful as they love them more, I'm not so sure.

DYANI LEWIS
Are the same areas of the brain activated when we view a loved one, compared with if we view something that we consider is beautiful?

SEMIR ZEKI
If you find that there is something especially beautiful about the loved person, yes, if the face is beautiful, yes. But the general activity of the brain when you look at the face of someone you love is quite different from the activity in the brain when you look at a painting which you find beautiful. By the way I do want to say one thing, because I sense that there's a lot of misunderstanding about that.
When we say that there's activity in the brain, when you look at something beautiful, when we say the activity is in these areas. We are not saying that there is a beauty spot in the brain, nor are we saying there's a love spot in the brain. This is an important question, I mean if you were to sit down and disconnect this area from the rest of the brain, you can't experience beauty or love. So these are areas which are especially active, and that's what you can say about them. In some cases for example colour visions a good example, there's an area of the brain V4 which is especially active when you see colours. If that area is damaged you can't see the world in colours anymore.
This has not been studied in as much detail for love and beauty, but there's certainly a set of areas in the brain which is very active when you look at the picture of someone you love. By the way, irrespective of gender, in other words, whether it is a straight or a gay or a lesbian relationship, as long as you love the person, there is activity in those areas. So again there is a sort of an almost footprint as it were which tells you that these areas are indicating that you are looking at a face of someone you love. But again, it does not define love at all, nor is there a love spot in the brain.

DYANI LEWIS
Another way of looking at activity in the brain is to look at what the neurotransmitters, the chemical messengers in the brain are doing. Have there been any studies looking at what different neurotransmitters might be doing when we view something that's beautiful?

SEMIR ZEKI
Not specifically, but a lot more has been done in the case of love. Neurotransmitters such as dopamine, oxytocin are all involved in love, but these neurotransmitters are also heavily linked chemically with other neurotransmitters. So that whether they're acting independently is not at all clear. Let me give you an example, the serotonin is heavily interlinked with oxytocins and dopamine, and in situations where people are passionate in love, the levels of serotonin go down to obsessive compulsive levels and levels of dopamine go up. We tend to talk about dopamine as being the important molecule of vasopressin, well actually they're all heavily interlinked with each other.
There are of course different kinds of dopamine receptors, and what the role of different kind of dopamine receptors are is not clear. But what is interesting is this, that if you take voles, well removed from humans, so you can talk about them more dispassionately. This is what should be known by Larry Young and Tom Insel in the United States, you take voles which are mountain voles, they are very very polygamous. You take prairie voles extremely monogamous. If you take a prairie vole, it mates with another prairie vole, it forms a terrific concept of its mate, and stays quite loyal. Even if you separate them for a long time they will mate with each other again afterwards.
Mountain voles on the whole no, they don't, they're very very promiscuous. Now if you take prairie voles and give them an antagonist to oxytocin, they also become quite promiscuous right? So here is a very important aspect of behaviour, which in human society we'd call adulterous behaviour. Which is regulated, perhaps not [uniquely], can be influenced by the levels of oxytocin activity and oxytocin receptors. So there are inroads being made into understanding this and they have got important implications.
Let's be quite clear about the implications of these things. People will often say to you that this is absolutely outrageous, ridiculous, you're talking about a kind of activity that belongs in the morals sphere, and talking about it in terms of single neurotransmitters. Well yes of course you are, because in fact the imbalance in neurotransmitters can affect people's behaviour.

DYANI LEWIS
Coming back to beauty and where the study of beauty originated, which is very much in the domain of the philosophers. Are there things that neurobiologists can still learn from artists and philosophers on the subject of beauty perception?

SEMIR ZEKI
Oh yes, neuroesthetics is very very young and a juvenile subject. It is heavily inspired by the previous debate in the humanities and the output of artists and musicians in formulating its questions. It is very important to realise, the questions that neuroesthetics addresses are vastly different from the questions that art history or philosophy of aesthetics addresses. But there is no doubt that many of the questions that neurobiology and neuroesthetics addresses, are heavily inspired by the debates of the humanities, and they have been formulated. There is a very important issue here which people don't seem to realise. I'm not being condescending, I think this applies to scientists as well as humanists.
The supposition that there is a different way of thinking in science and a different way of thinking in the humanities is not true. The process of thinking, of inductive, deductive and analogic thinking in science and in the arts are the same. And in many ways the conclusions reached in the humanities and the arts, are conclusions reached by the same brain processes as one reached in the sciences. It's just that in science you require more proof. Now in the case of proof, I think you can say that the work of, if you take Sophocles or Shakespeare, has actually undergone quite rigorous statistical tests, in that it has been appreciated by so many people over so long a period of time, that it carries with it some truths.
Therefore it is worth considering what these truths are, and then applying them in neurobiology. This is extremely important to realise, that it's not you cannot gain knowledge from the arts, you can gain a great deal of knowledge from the arts, not just pleasure but knowledge, and then apply them studying the brain.

DYANI LEWIS
And now that we do have this medial orbito frontal cortex that we've focused in on as lighting up, as being active when we perceive beauty, where to next?

SEMIR ZEKI
Oh well there's a huge amount still to be decided on. First of all are there subdivisions in medial orbito-frontal cortex. Secondly what are the properties of a stimulus that activate the areas. This going back to a question you asked earlier, are there what I call significant configurations in the stimuli that activate the visual or the audible areas, in a particular way. And only when these areas are activated in that particular way do you get activity in the medial orbito-frontal cortex. What is the relationship of the transmitters in the medial orbito-frontal cortex to each other and to other transmitters?
Also for example it is quite interesting to consider that a lot of what we consider to be very beautiful and very moving, is actually quite painful. I mean nobody's going to call the Pieta of Michelangelo a joyful thing, it's not, it's a very powerfully disturbing and arousing thing. But it's also experienced as very very beautiful. Or nobody's going to call the Hammerklavier of Beethoven as joyful dancing music, because it's not, but it's very beautiful. So there are all these questions that remain to be answered.
But I take you back to one of the first questions you asked me, which is the importance of culture and learning. Now it is quite important to learn how a painter or an artist would react to works of visual art. But also how a painter and artist would react at different stages of his or her development. It is quite interesting, Cezanne, Cezanne for example painted the Montagne Sainte-Victoire, how many times? Maybe 110 times. He said that he himself was changing as he was painting it. So these are all interesting questions again to be address. The same is true for musicians. It must be true that our aesthetic sense develops as does our expertise, and does our connoisseurship.
But then you see you enter a different world, which is the plasticity of the brain, how hospitable is the brain to new ideas, it's what periods is it hospitable to new ideas, and how restricted it is to receiving new ideas. They are all very interesting general neurobiological questions, which can be applied specifically to works of art and to basically the aesthetic experiences.

DYANI LEWIS
Semir Zeki thank you for being our guest today on Up Close.

SEMIR ZEKI
Thank you for having me.

DYANI LEWIS
Semir Zeki is Professor of Neuroesthetics in the Department of Cell and Developmental Biology at University College London.