How stress can lead to inequality

February 18, 2015

Stress is a staple of our lives today, and we know intuitively that it can influence our confidence in competing with others. But how exactly does stress do that? Scientists at EPFL have carried out the first behavioral study to show how stress actually affects our degree of confidence, implying that it can even be a cause of social inequality rather than just a consequence of it. On a biological level, the researchers have also associated the effects of stress with the release of the hormone cortisol. The study is published in Psychoneuroendocrinology.

Confidence is essential to our ability to compete in society; when we don't feel confident, we are less likely to make the kind of decisions that can give us a financial and social edge over others. By driving social competition, confidence becomes central in the organization and function of human societies, and marks the way individuals interact with each other.

At the same time, little is known about what influences people's confidence. Two major factors seem to be stress and the person's general anxiety. Technically, this is referred to as "trait anxiety", and it describes how prone a person is to see the world as threatening and worrisome. The question, however, is how stress and trait anxiety impact an individual's confidence in a competitive context.

Stress and confidence

The teams of Carmen Sandi at EPFL and Lorenz Goette at UNIL have now shown that stress can actually boost the competing confidence of people with low trait anxiety, but significantly reduce it in people with high trait anxiety. The scientists designed an elegant behavioral experiment, which began with more than two hundred people taking two online tests: one to assess their IQ, and one to measure their trait anxiety.

A week later, about half of the study's participants underwent a standard psychological procedure (called TSST-G) designed to cause acute social stress, such as going through a mock job interview and performing mental arithmetic tasks before an impassive audience. The other half of the participants formed the control group, and did not undergo the stress-inducing procedure.

All participants, stressed and non-stressed, were then given two options in a game where they could win money: they could either take their chances in a lottery, or they could use their IQ score to compete with that of another, unknown participant's; the one with the higher IQ score would be the winner.

In the non-stressed, control group, nearly 60% of participants chose the IQ score competition over the lottery, showing overall high confidence in the participants, regardless of their trait anxiety scores. But in the group that experienced stress before the money game, things were different. The competitive confidence of participants varied depending on their trait anxiety scores. In people with very low anxiety, stress actually increased their competitive confidence compared to their unstressed counterparts; in highly anxious individuals, it dropped.

The findings suggest that stress is a catalytic force acting on a person's competitive confidence. Stress, it seems, can raise or suppress an individual's confidence depending on their predisposition to anxiety.

Stress and cortisol

The researchers also found that the effects of stress on the participants' confidence were mediated by the hormone cortisol, which is normally released from the adrenal glands, on the top of our kidneys, in response to stress. The team examined saliva samples from the stressed participants for the presence of cortisol. In people with low anxiety, those that showed higher confidence also showed a higher cortisol response to stress. But in highly anxious people, high cortisol levels were associated with lower confidence, which connects the behavioral effects of stress to a biological mechanism.

The findings of this behavioral experiment can be seen as a simulation of confidence in social competition and the way it relates to socioeconomic inequality. Studies have shown that, in areas with wide socioeconomic inequality (e.g. a wide rich-poor gap), people on the low end of the social ladder often experience high levels of stress as a consequence.

"People often interpret self-confidence as competence," says Carmen Sandi. "So if the stress of, say, a job interview, makes a person over-confident, they will be more likely to be hired - even though they might not be more competent than other candidates. This would be the case for people with low anxiety."

Far from being only a product of competitive inequality, stress must now also be regarded as a direct cause of it. In other words, stress can become a major obstacle in overcoming socioeconomic inequality by trapping highly anxious individuals in a self-perpetuating loop of low competitive confidence.

Carmen Sandi is now interested in relating the effect of stress on confidence with brain imaging. Although there is much yet to be learned in this area, she believes that it can change the way we look at social dynamics as a whole. "Stress is an important engine of social evolution," she says. "It affects the individual, and by extension society as whole."
This work represents a collaboration of EPFL with the University of Lausanne (UNIL). The study was partly sponsored by the Swiss National Science Foundation.


Goette L, Bendahan S, Thoresen J, Hollis F, Sandi C. Stress pulls us apart: Anxiety leads to differences in competitive confidence under stress. Psychoneuroendocrinology 18 February 2015.

Ecole Polytechnique Fédérale de Lausanne

Related Stress Articles from Brightsurf:

Stress-free gel
Researchers at The University of Tokyo studied a new mechanism of gelation using colloidal particles.

Early life stress is associated with youth-onset depression for some types of stress but not others
Examining the association between eight different types of early life stress (ELS) and youth-onset depression, a study in JAACAP, published by Elsevier, reports that individuals exposed to ELS were more likely to develop a major depressive disorder (MDD) in childhood or adolescence than individuals who had not been exposed to ELS.

Red light for stress
Researchers from the Institute of Industrial Science at The University of Tokyo have created a biphasic luminescent material that changes color when exposed to mechanical stress.

How do our cells respond to stress?
Molecular biologists reverse-engineer a complex cellular structure that is associated with neurodegenerative diseases such as ALS

How stress remodels the brain
Stress restructures the brain by halting the production of crucial ion channel proteins, according to research in mice recently published in JNeurosci.

Why stress doesn't always cause depression
Rats susceptible to anhedonia, a core symptom of depression, possess more serotonin neurons after being exposed to chronic stress, but the effect can be reversed through amygdala activation, according to new research in JNeurosci.

How plants handle stress
Plants get stressed too. Drought or too much salt disrupt their physiology.

Stress in the powerhouse of the cell
University of Freiburg researchers discover a new principle -- how cells protect themselves from mitochondrial defects.

Measuring stress around cells
Tissues and organs in the human body are shaped through forces generated by cells, that push and pull, to ''sculpt'' biological structures.

Cellular stress at the movies
For the first time, biological imaging experts have used a custom fluorescence microscope and a novel antibody tagging tool to watch living cells undergoing stress.

Read More: Stress News and Stress Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to