The telling figure below from an NBER paper (wp) by Allen, Dechov, Pope and Wu has been shared by several people this summer. From data on almost 10 million marathon finishing times, they show how people use their prospective finishing time as motivation to provide more effort and bunch at every 30 min. interval.
Figure 2. Distribution of marathon finishing times-Allen Dechov Pope Wu 2014 Reference-Dependent Preferences- Evidence from Marathon Runners
Noah Smith has a nice take on the Singularity, or the Slackurality, which is his prediction of what will happen as intelligent machines, like intelligent humans, will come to have other motivations than just “inventing thinking beings more intelligent than themselves.” Someone meeting this AI-slacker might have to exclaim: “How unsearchable are his judgments and how inscrutable his ways!” (Rom 11:33)