Do we really have a 'best side'?
Welcome to That Thinking Feeling, a blog about the everyday questions that psychology can answer. I used to be a psychology researcher and lecturer, so I have some of the answers! Others I have to look up, but then distil them for you in a fun way.
Surprisingly, psychology can tell us whether we have a best side! But before we begin, take a selfie – but make sure you’re smiling! (This is for science. I am not just asking you to smile for no reason, promise.)
OK. Now, have a look at that selfie. Have you turned sideways at all, even a little bit? Which side of your face is showing more? (This might be a tricky question to answer – my phone keeps selfies in mirror image format, but yours might flip it over.) I bet you’ve got more of the left side of your face in the photo – by which I mean the left as viewed by someone looking at you, not your own left.
Now, the time I tried getting my students to take a selfie when I was teaching them about this in a classroom it only half-worked, so I could be wrong. But when Bruno and Bertamini [i] tested the idea by asking 300 people in Italy and the UK to take selfies, they found that most of them did have more of the right side of their faces showing than the left side, regardless of things like handedness and gender. Since then, the same thing has been found in people in multiple different countries including Thailand, Brazil and Russia [ii].
So, people clearly think that they have a ‘best side’. Why, though?
The main theory is that people show more emotion on the right side of their face than the left side. Allow me to demonstrate with a selfie of my own and the magic of photo editing.
Which one of these versions of me is looking most happy? I’d say it’s the right side mirrored one: my mouth is smiling more; my eyes are wider open and my eyebrows are raised more than the left side mirrored one. Way back in 1978, researchers [iii] suggested that emotion is expressed more strongly on the left side of the face. This is because the bit of the brain that deals with showing emotion on the left side of the face is slightly quicker and more expressive than the bit that deals with showing emotion on the right side of the face.
We like seeing a facial display of emotion. It lets us know what to expect from the other person, what actions might be socially appropriate, whether (if they’re looking fearful) we should check behind us for large predators like lions or overbearing bosses. I think what’s happening when we show our right side to the camera is probably the result of all the times we got a sliiiightly more beneficial response from showing other people the right sides of our faces than we did when we showed them the left sides of our faces. Though there are situations in which this can be undesirable – for example, scientists are judged as more scientific if they are showing the other side of the face in a portrait, perhaps because they are perceived as less ‘emotional’ and more ‘rational’ [iv]. (I am getting a strong whiff of sexism here, what joy.)
So… do we show all emotions more strongly on the right side of the face? Maybe.
Before we get to the answer, it’s important to know that much of the brain is contralateral. This means that in most, but not all, cases, the left side of the brain deals with the right side of the body, and the right side of the brain deals with the left side of the body.
Unfortunately, to make matters wildly confusing, when researchers talk about the left side of the brain, they’re talking about the left side as perceived by the person with the brain. When researchers talk about the left side of the face, they’re talking about the left side as perceived by someone looking at that face.
I am not good at left and right at the best of times so this is an absolute nightmare for me.
Bear all this in mind as I tell you about three theories:
The right-hemisphere hypothesis [v] says that the right hemisphere is more involved in every emotion than the left hemisphere. If this is correct, every emotion should be shown more on one side of the face than the other.
The emotional-valence hypothesis [vi] says that the right hemisphere is more involved in negative emotions like fear and grief, while the left hemisphere is more involved in positive emotions like love and happiness. If this is correct, we should show negative emotions more strongly on one side of the face and positive emotions more strongly on the other.
The approach-withdrawal hypothesis [vii] says that the right hemisphere is more involved in emotions that make us want to withdraw from something, and the left in emotions that make us want to approach something. This overlaps quite a lot with the emotional-valence hypothesis because negative emotions typically make us want to withdraw (think of disgust), while positive emotions make us want to approach (think of love) – but this is complex because of emotions like sadness, which are negative but may make us want to approach others for support.
We don’t yet know which of these theories is correct, if any. Maybe more than one of them is right [viii]! To make matters more complicated (and also more interesting), we are far from the only animals to have some kind of difference in the way the two halves of the brain deal with emotion. In fact, it seems to be common to all vertebrates [ix], so it’s probably quite an old feature of the brain, in evolutionary terms.
To finish, I’d like to tell you one last cool fact from Bruno and Bertamini’s selfie study. Back in the days before cameras, people couldn’t take selfies (this is not the cool fact, please bear with me for a couple of sentences). However, if you had access to the right materials, you could draw or paint yourself, like Sofonisba Anguissola in the painting below.
Starting around the 17th century, there was a huge rise in the number of artists choosing to paint self-portraits showing the left side of their faces – except it’s actually their right side, because good mirrors had started to become available. Later, when photography started becoming widespread, the trend reversed – right cheeks are really right cheeks again, and not left cheeks in reverse.
[v] Borod, J. C., Kent, J., Koff, E., Martin, C., & Alpert, M. (1988). Facial asymmetry while posing positive and negative emotions: Support for the right hemisphere hypothesis. Neuropsychologia, 26(5), 759-764.
[vii] Davidson, R. J., Ekman, P., Saron, C. D., Senulis, J. A., & Friesen, W. V. (1990). Approach-withdrawal and cerebral asymmetry: emotional expression and brain physiology: I. Journal of Personality and Social Psychology, 58(2), 330.
[viii] Killgore, W. D., & Yurgelun-Todd, D. A. (2007). The right-hemisphere and valence hypotheses: could they both be right (and sometimes left)? Social Cognitive and Affective Neuroscience, 2(3), 240-250.
[ix] Leliveld, L. M., Langbein, J., & Puppe, B. (2013). The emergence of emotional lateralization: evidence in non-human vertebrates and implications for farm animals. Applied Animal Behaviour Science, 145(1-2), 1-14.