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Workplace stress: Opposites attract

August 24, 2011

Picture by Michael Schmid (Wikipedia)

Individual atoms are like tiny bar-magnets pointing in a certain direction, and the arrangement of a large number of these atomic magnets on a periodic lattice determines the macroscopic magnetic properties of a bulk material. In most materials, atoms at different lattice sites are oriented randomly and experience thermal fluctuations, resulting in no net magnetization. Under certain conditions however, in some materials like iron, nickel and cobalt, there can be an order in the orientation of atoms at different lattice points.

For example, if all the atomic magnets point in the same direction (“ferromagnetism”), the whole material acquires a macroscopic magnetization and behaves as the familiar magnet that we stick onto our refrigerators. This long range order arises out of a strong interaction (“exchange coupling”) between neighbouring atomic magnets in the lattice. The magnitude and sign of this exchange energy is a result of the quantum mechanical behaviour of the atoms and details of the lattice. If this exchange energy has the opposite sign, it can result in “anti-ferromagnetism”, where all the neighbouring atoms are anti-aligned to each other i.e. an atom pointing ‘up’ is surrounded by atoms pointing ‘down’ and vice versa. Imagine moving along a line in such a lattice – one would see a periodic arrangement of ‘up, down, up, down’ repeat forever.

Researchers at the Hitachi corporation in Japan have now seen such anti-ferromagnetic behaviour in the stress levels of humans in the workplace. They measured the stress levels of 630 people working in 11 different divisions of a software development company using standard questionnaires. They also monitored face-to-face interactions using “sociometric badges”  that the employees were told to wear for a 4-week period. The badges were equipped with accelerometers, infrared sensors and microphones to measure the movement and speech of every employee. A face-to-face communication ‘lattice’ was then constructed by making the people as nodes and establishing links between people who had on average more than five minutes per day of communication time.

The scientists calculated the correlation between the stress levels of employees as a function of the distance (number of links) between them on the ‘communication lattice’. Remarkably, they found a negative correlation between the stress levels of nearest neighbours (people separated by a single link). For next-nearest neighbour employees (separated by two links), the correlation was positive. For employees separated by three links, the correlation was found to be negative again, and the alternating positive-negative pattern continued till the maximum separation of five links. The result was replicated in all the different divisions of the company.

This is clear evidence of anti-ferromagnetic order, and it seems in the workplace, relatively low stress is experienced by people around other highly stressed people and vice versa. This is counter-intuitive and even more surprising considering the results of similar experiments conducted in groups of friends or family i.e. people who know each other well, where a positive correlation and ‘diffusion’ of stress between individuals was found. There, being around stressful people meant increased stress for the person.

The authors attribute this difference in the ‘macroscopic’ behaviour of the group to the difference in the ‘microscopic’ details of the human-human interactions. In analogy with statistical physics, they model human-human interaction as an “exchange coupling” and simulate the minimum energy configuration for a particular communication lattice. The situation of the ‘friends-group’ and the ‘workplace-group’ was reproduced just by taking opposite signs of the exchange coupling, suggesting a major difference in the nature of human-human interaction in the two cases. People tend to be competitive and less cooperative in their interactions in the workplace, while they tend to be kind, helpful and empathetic towards friends and family.


Watanabe, J., Akitomi, T., Ara, K., & Yano, K. (2011). Antiferromagnetic character of workplace stress Physical Review E, 84 (1) DOI: 10.1103/PhysRevE.84.017101


From → Physics, Statistics

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