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Inequality's Unhealthy Consequences

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CAN ECONOMIC INEQUALITY BE HAZARDOUS TO A SOCIETY’S HEALTH? Dr. Akihiro Nishi, assistant professor of epidemiology at the Fielding School, notes that there is substantial evidence showing that wide gaps between rich and poor are associated with higher mortality rates. The reasons are unclear, but scholars have speculated that highly unequal societies may result in increased overall stress levels, leading to higher rates of cardiovascular disease and other stress-related conditions. More inequality can also mean less social support, reflected in reduced access to health care and other health resources among large segments of the population.

In work he started as a postdoctoral researcher at Yale University and is continuing at the Fielding School, Nishi is building on those findings while adding a wrinkle: The visibility of wealth inequality within a society appears to be more harmful than the presence of inequality itself. Publishing in the journal Nature in 2015, Nishi and colleagues concluded that visible inequality — from knowing about the salaries of others to seeing evidence of a neighbor’s wealth in the form of a luxurious home or fancy car — has a negative effect on levels of cooperation, and contributes to even greater inequality.

For the Nature study, Nishi’s group conducted an experiment in the form of an online game, wherein participants were placed into computer-simulated “societies” with varying degrees of inequality. Within each society, some individuals could see how much money their neighbors had while others could not. The game repeatedly asked participants to make choices that tested their interest in cooperating with others — for example, they could invest in their neighbors with the potential of gaining financially in return, or they could keep their money to themselves. In each group, participants could see their neighbors’ choices after every round, potentially affecting their own choices in future rounds.

When participants in the experiment didn’t know about the wealth of others, their level of cooperation wasn’t affected by their society’s economic inequality. But in unequal societies where wealth was visible, wealthier individuals were less likely to invest in their neighbors, widening the gulf between rich and poor. “We know that when a comparison of salaries is possible within a company, it can lead to lower levels of job satisfaction,” Nishi says. “Our study suggests that visible wealth inequality also leads to lower levels of social cohesion, which is not what we would hope for from the standpoint of public health.”

Nishi notes that although conclusions about the public health effects of visible wealth inequality can’t be drawn from the Nature study, it raises public health questions for future study. Among the questions Nishi intends to pursue: whether policies to make wealth inequality less visible — through pay secrecy or school uniforms, for example — might result in mental health benefits and improved social cohesion within a company or a community.