We introduce a construct called “humanness sensitivity,” which we define as the ability to recognize uniquely human characteristics. To evaluate the construct, we used a “concurrent study design” to conduct an internet-based study with a convenience sample of 42,063 people from 88 countries.We sought to determine to what extent people could identify subtle characteristics of human behavior, thinking, emotions, and social relationships which currently distinguish humans from non-human entities such as bots. Many people were surprisingly poor at this task, even (...) when asked simple questions about human relationships or anatomy. Participants were best at identifying subtle aspects of human cognition and worst at identifying subtle aspects of human communication. Test scores were good predictors of whether someone was employed and modest predictors of other self-reported criterion measures. We also found that people identifying themselves in marginal societal categories identified themselves as less human and also scored lower on our test. As computers continue to become more human-like, our study suggests that the vast majority of humankind will likely have great difficulty distinguishing them from people. Can methods be devised for improving this ability? Might humanness sensitivity help people to make such distinctions? Will people who excel at differentiating humans and non-human entities—like the “blade runners” in the 1982 and 2017 feature films—someday hold a special place in society? (shrink)