Social psychologists have long known that men tend to express love first in relationships, even though public perception is just the opposite, and the new project started by confirming those assumptions.

In surveys of 45 people who walked by a street corner, Ackerman and colleagues found that 65 percent of people believed that women usually said, “I love you” first in relationships, while 85 percent believed that women were the first to develop serious feelings.

But two subsequent studies, in which people who ranged in age from their mid-20s to their 60s reflected on their current or most recent relationships, showed that men actually declare love first about 70 percent of time.

In a series of three follow-up studies, people responded to questions about how happy it made them to hear declarations of love. Some imagined being in a fictional new relationship. Others had actually just been told “I love you” for the first time in a relationship in the prior week. Their answers revealed a range of nuances.