Yellen and Akerlof have collaborated on research, including topics such as poverty, unemployment and a paper on the costs of out-of-wedlock childbearing. One of their most talked-about papers at Berkeley, on why lower wages don’t always lead to higher employment, came from the experience of hiring a nanny for the first time. “Firms are not always willing to cut wages, even if there are people lined up outside the gates to work. So why don’t they?” asks Yellen. The couple’s conclusion: some employers set pay higher to demonstrate that they value employees in a way that motivates them to do good work, even when markets are ready to undercut those wages. Yellen says Akerlof (along with James Tobin) has been her biggest intellectual influence. Both frequently state that their lone disagreement is that she is a bit more supportive of free trade than he is.