The impact of ­COVID-19 on the physical health of the world’s citizens is extraordinary. By mid-May there were upward of four million cases spread across more than 180 countries. The pandemic’s effect on mental health could be even more far-reaching. At one point roughly one third of the planet’s population was under orders to stay home. That means 2.6 billion people–more than were alive during World War II–were experiencing the emotional and financial reverberations of this new coronavirus. “[The lockdown] is arguably the largest psychological experiment ever conducted,” wrote health psychologist Elke Van Hoof of Free University of Brussels-VUB in Belgium. The results of this unwitting experiment are only beginning to be calculated.

The science of resilience, which investigates how people weather adversity, offers some clues. A resilient individual, wrote Harvard University psychiatrist George Vaillant, resembles a twig with a fresh, green living core. “When twisted out of shape, such a twig bends, but it does not break; instead it springs back and continues growing.” The metaphor describes a surprising number of people: As many as two thirds of individuals recover from difficult experiences without prolonged psychological effects, even when they have lived through events such as violent crime or being a prisoner of war. Some even go on to grow and learn from what happened to them. But the other third suffers real psychological distress–some people for a few months, others for years.

— Read on www.scientificamerican.com/interactive/the-biggest-psychological-experiment-in-history-is-running-now/