By Emma Young
One of the best-known but also most contentious ideas in psychology has to be that there are “universal” expressions of at least some human emotions. According to this idea, which was pioneered by Paul Ekman, particular patterns of facial muscular movements are reliable indicators of anger, disgust, fear, surprise, happiness, sadness and contempt, no matter where you are in the world. In other words, these expressions are a fundamental part of being human.
The idea of universal emotional expressions has been challenged, however. Some psychologists argue that even within the US or UK, say, facial movements that we routinely associate with certain emotions — such as a smile with feeling happy — don’t reliably match in that way. Others think that facial “expressions” are better understood as social signals. According to this model, when someone smiles, it doesn’t mean that they’re happy but rather that they want to be sociable and cooperative, while a frown doesn’t mean “I’m angry” but rather “I want you to bend to my will”. Physical social signals, beyond facial movements, have been identified, too. And now a new paper in Scientific Reports enters this field, with the claim that a downwards head-tilt is a “possibly universal” signal of dominance.
Zachary Witkower at the University of Toronto and colleagues studied members of a remote community in the forested Bosawas Biosphere Reserve in Mayangna, Nicaragua. Relatively few of the 119 adults (aged 18-75) were fluent in Spanish, most had never seen a US TV programme, their knowledge of global celebrities was paltry, and 94% had never used the internet. So, the team argues, they are unlikely to have learned particular ways of responding or behaving from Western culture.
Each participant was shown two pairs of images. The first pair showed just the eyebrow/eye/nose bridge regions of two computer-generated male heads. These heads, which had neutral facial expressions, were identical, except that one was upright and the other was tilted forwards 10 degrees. An experimenter said: “Please select the image in which the person is likely to be a leader because he is willing to use aggression and intimidation to get his way” and the participants made a choice. Then they were shown the same two heads, but in full this time, and were asked the same question.
When American participants were given this task, they tended to choose the head-tilted image. This was true whether they saw the eye region or the full head. And Witkover and colleagues found the same thing for this remote population. When only the facial strip was shown, the head-tilted version was chosen as the likely aggressive leader 72% of the time. When full faces were shown, the head-tilted version was chosen 84% of the time. A forwards head tilt was clearly associated with dominance/aggression.
As the effect was stronger for full faces, it might be that the whole face gives more anger/dominance information than the eye region alone. However, as the researchers note, because the full-face pair always followed the eye-region pair, participants might just have become more confident in their perceptions of anger/dominance on the second viewing.
A big question is: what explains the finding?
The researchers argue that when the head is tilted down a little, this gives the illusion that the brow has been lowered. Numerous studies have linked a lowered, frowning brow with anger, dominance and threat. This new research “provides the first evidence to suggest that humans across highly diverse cultural contexts perceive dominance from a downwards head tilt alone,” the team writes. And because they think it’s due to the illusion that the brow has been lowered, signalling anger/threat, they argue that “this visual illusion might therefore be a universal feature of human cognition”.
Why should a lowered brow signal threat/anger? The team suggests that we evolved to automatically associate angles in our environment with threat and danger. According to this idea, sharp, angular things (like rocks) would generally have been dangerous — and the angular V-shape that forms when the brow is lowered might have come to signify threat, too.
But there are other potential explanations for their findings. Their theory could even be flipped on its head. Picture someone about to run at you, to attack. Their head will be tilted forwards, not straight upright. So a downward tilted head could itself be a signal of threat. And a frown may give the illusion that this is happening — rather than a downward head tilt giving the illusion of a scowl.
Claims of human “universals” are always subject to strong scrutiny. The team’s claims will be no different. It will take more research, especially on more non-WEIRD populations, to rule out other possibilities and firm up their ideas.