U.S. researchers report they've found the first evidence people use the same brain circuitry to figure out space, time and social distances.

Scientists at Dartmouth College conducted experiments to determine whether there is an overlap, or a common mechanism, in the brain areas used to represent time, space and social relationships.

The analyzed brain scans of study participants while they viewed objects photographed at different distances, viewed photos of friends or acquaintances, and read phrases referring to the immediate or more remote future.

"The results showed that the same brain patterns that decide whether something is physically near to us versus far away also decide whether we are thinking about the near or distant future or seeing a friend versus an acquaintance," senior author and psychology Professor Thalia Wheatley said.

"In other words, there is a common neural code for space, time and social distance. Near, now and dear [friends] activate one pattern and far, later and acquaintance activate a different pattern."

The results suggest why people use distance metaphors to talk about time and friendship, such as close friends or distant relatives, Wheatley said.

"These metaphors stick because they echo the very neural computations involved," she said. "Our brains use distance to understand time and social connectedness."

"This mapping function may have a particularly important benefit in determining whether we care enough to act: Is something happening here, now, to someone I love? Or over there, years from now, to a stranger?"