Copyright © 2007-2017 Russ Dewey
Darwin commented on the inborn emotional expressiveness of babies. Babies are also able to interpret facial expressions.
Cohn and Tronick (1983) had mothers imagine how they felt on a day when they were tired. The mothers were instructed to look away from the baby, speak in a monotone, and turn the corners of their mouths down. The babies responded by crying, grimacing, and otherwise showing distress.
Paul Ekman is a leading investigator of facial expression. He is famous for a coding system that identifies 80 distinct muscles in the face.
As mentioned on the previous page, Ekman's system provided an objective way to define facial expressions, well adapted to computerized facial recognition programs. It is a very useful tool for researchers.
What coding system did Ekman develop? Why is it useful for researchers?
Ekman's early work tested Darwin's idea that all humans interpret facial expressions the same way. Ekman showed pictures of humans expressing happiness, fear, surprise, anger, disgust, and sadness to people from cultures all over the world.
Faces interpreted the same way by people in different cultures
People in different cultures all interpreted these facial expressions the same way. The expressions show anger, fear, disgust (top row) then surprise, happiness, and sadness (bottom row).
What is an easy way to tell a sincere smile from a nervous or polite smile?
Using his system, Ekman could document the fact that (for example) there are at least four distinct smiles that do not necessarily convey happiness. One type, with a tense upper lip, masks anger.
Another type, the insincere smile, lasts too long, up to 10 seconds. (A genuine smile is more likely to last 2 seconds.) The insincere smile is frozen into place with the aid of clenched teeth.
A third type of smile is intended to cushion criticism. The lips are closed and the corners of the mouth are drawn upward. It is the type of smile a teacher might use when telling a student what is wrong with a term paper.
The fourth smile is a "reluctant, compliant smile" of someone who is giving in to pressure from somebody else. It might be called a grim smile. The eyes are cast downward, the corners of the mouth are drawn sideways and slightly up (Goleman, 1984).
Ekman and Davidson (1993) reported that raised cheeks and "crow's feet" wrinkles around the eyes often accompany a truly happy smile. Non-happy smiles (such as the four types outlined above, are not accompanied by this raising of cheeks and wrinkling around the eyes.
Ekman found that a French neurologist, Duchenne de Boulogne, had previously reported this fact in 1862. Duchenne observed that "the emotion of frank joy" is expressed by pulling up the sides of the mouth, which "obeys the will," and by movement of the muscles around the eyes, which is "only put into play by the sweet emotions of the soul..."
What is Duchenne's marker?
Ekman called the latter Duchenne's marker. Ekman and co-workers showed that Duchenne's marker could be easily observed in real time (without slowing down a video recording) and that it was indeed useful in distinguishing happy smiles from other types.
Crying is an obvious way that humans express emotion. Other primates cry out (vocalize) when separated from caregivers, but they do not produce tears.
Kim Bard notes that she has "direct experience with parenting over 50 chimpanzee infants" but has never observed tears. Bard also says chimp babies will immediately stop crying out, when re-united with caregivers.
Human babies like her own were sometimes inconsolable, continuing to cry after being picked up. She did not observe this in chimps.
Elephants can produce tears. Some experienced elephant handlers claim elephant tears can reflect emotional states, but this has not been verified in a way that satisfies scientists who study emotion. Most believe that tears expressing emotion are unique to humans.
In humans, there are three types of tears: continuous tears bathing the cornea, reflex tears produced by irritants, and emotional tears arising from sadness or joy. The first two types are shared by other animals (and may account for elephant tears).
Emotional tears in humans have been described as an "enigma." They are instinctive, because children born deaf and blind will weep without any opportunity to learn this behavior.
If the ophthalmic branch of the fifth facial nerve is severed, reflex or irritant weeping is inhibited. But emotional tears can still occur (Suplee, 1987).
One noted expert on tears, biochemist Dr. William H. Frey, analyzed tears and found unusual levels of stress-related chemicals in them. He proposed that tears, in humans, might be involved in relieving emotions by expelling stress chemicals (Brody, 1982).
What biological function did Frey propose for tears?
Other exocrine processes, like exhaling, urinating, defecating, and sweating, all release potentially toxic substances from the body. Frey suggested that tears might be no exception. He proposed that this might account for the subjective feeling of relief after a good cry, or the feeling of a need to cry building up after a long time without tears.
Consistent with this, children who are unable to cry (due to a genetic defect) show exaggerated stress responses. However, some researchers (such as Murube, Murube, and Murube, 1999) expressed skepticism, saying the chemicals identified in tears by Frey are not toxic, and the quantities involved are not great enough to make a difference. A full-blown crying episode produces barely 1 millilitre of liquid.
What are gender-related differences in reported frequency of crying?
After becoming interested in the stress-reducing function of tears, Frey asked several hundred volunteers in the Chicago area to keep a journal for several months indicating when and under what circumstances they cried.
Women reported crying an average of five times a month, men an average of once a month. 45% of the men and 6% of the women did not cry at all during the time Frey collected data. These findings were replicated several times by later investigators.
Some women (all normal) cried every day. Women were also more likely to report "a lump in the throat" and to shed tears. Men reported that, in over three-quarters of cases, tears "welled up" in their eyes but did not actually flow. This might be partly due to the fact that men have physically larger tear ducts.
In Frey's sample, sobbing occurred in 14% of the women's crying incidents, 10% of the men's. Crying episodes lasted an average of six minutes for each occurrence, and that was the same for men and women.
When did most crying occur?
The most frequent trigger of crying was (1) arguments and (2) watching sad movies or television. Both tended to occur around 7 to 10 p.m. at night.
One in five crying episodes was provoked by happiness rather than sadness or sympathy. Several researchers reported that crying in response to happy events was found almost entirely in men.
Does crying produce relief? This has been a folk belief for over 100 years. In Frey's sample, 85% of the women and 73% of the men reported feeling better after crying. One study found that criers felt worse immediately after crying, but 90 minutes later felt much better than non-criers.
Cross-cultural research shows that crying is less common in societies that are less tolerant of emotional expression (van Hemert, van de Vijver, and Vingerhoets, 2011). Large gender differences (with more women crying) were associated with wealthier, more democratic, and more feminine countries, according to the researchers.
In a comprehensive review of theories about crying, Vingerhoets, Cornelius, van Heck, and Becht (2000) point out that most theorists have looked for direct biological causes of crying, but indirect social/evolutionary explanations may be more likely.
They cite a suggestion by F. Roes that crying evolved as a way of eliciting sympathy and warding off aggression. Crying, like other appeasement displays, mimics the behavior of the young. The "kinderschema" (child pattern) was noted by Eibl-Eibesfeldt in his studies of human ethology.
Smiling, whimpering, and other submission displays show a similar pattern: they use child-like features to inhibit aggression in more dominant animals. Consistent with the idea that tears lower aggression in dominant animals, Gelstein, Yeshurun, Rozenkrantz, Shushan, Frumin, Roth, and Sobel (2011) found that sniffing a vial of tears (compared to sniffing a vial of saline water) lowered testosterone levels in men.
Psychology and neuroscience professor Robert R. Provine suggested adult tears in humans evolved opportunistically as a social display. Originally, the presence of NGF (nerve growth factor) in tears was a way of healing eye injury. NGF (nerve growth factor) is found in tears, and it is one of Provine's research specialties. As Provine put it:
The NGF concentration in tears, cornea, and lacrimal glands increases after corneal wounding, suggesting that NGF plays a part in healing. More directly, the topical application of NGF promotes the healing of corneal ulcers and may increase tear production in dry eye . . . Although more of a scientific long shot, I suggest that tears bearing NGF have an anti-depressive effect that may modulate as well as signal mood.
Then, over time, tears became a signal of a need for caregiving.
Non-emotional, healing tears may have originally signaled trauma to the eyes, eliciting caregiving by tribe members or inhibiting physical aggression by adversaries. This primal signal may have later evolved through ritualization to become a sign of emotional as well as physical distress.
What did Provine suggest about how adult crying evolved?
In support of this theory, Provine points out some distinct differences between tears in childhood and adulthood. In childhood, crying is sustained and loud. In adults, it is private, mostly observable in close quarters. Provine elaborated:
As an adult, you cry much less than when young, and your crying is more often subdued, teary weeping than the demonstrative, vocal sobbing of childhood. . .
[T]he trauma that causes your crying is now more often emotional than physical. However, whether intentional or not, as adult or child, you cry to solicit assistance, whether physical aid or emotional solace.
Paradoxically, your adult cry for help is more private than the noisy...
Brody, J. E. (1982, August 31). Biological role of emotional tears emerges through recent studies. New York Times, p.19.
Cohn, J. E, & Tronick, E. Z. (1983). Three-month-old infants' reaction to simulated maternal depression. Child Development, 54, 185-193.
Ekman, P. & Davidson, R. J. (1993) Voluntary smiling changes regional brain activity. Psychological Science, 4, 342-345.
Frey, W. H. (1985) Crying: The Mystery of Tears. Minneapolis, MN: Winston Press.
Gelstein, S., Yeshurun, Y., Rozenkrantz, L., Shushan, S., Frumin, I., Roth, Y., & Sobel, N. (2011). Human tears contain a chemosignal. Science, 331, 226-230. doi:10.1126/science.
Goleman, D. (1984, May 22). Human emotion under new scrutiny. New York Times, pp.17,21.
Hemert, D. A. van, Vijver, F. J. R. van de, & Vingerhoets, A. J. J. M. (2011, April 28) Culture and Crying: Prevalences and Gender Differences. Cross-Cultural Research. Retrieved from: http://journals.sagepub.com/
Murube, J., Murube, L., & Murube, A. (1999) Origin and types of emotional tearing. European Journal of Ophthalmology, 9, 77-84.
Popova, M. (2012, September 7) Emotional tearing. Brainpickings. Retrieved from: https://www.
Suplee, C. (1987, May 10) Chemistry sheds light on tears. Washington Post. Retrieved from: http://articles.
Vingerhoets, A. J. J. M., Cornelius, R. R., Heck, G. L. van, & Becht, M. C. (2000). Adult crying: A model and review of the literature. Review of General Psychology, 4, 354-377.
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Copyright © 2007-2017 Russ Dewey