New Law Guiding the Way Humans Perceive the World

Laws of perception explain why people see the world the way they do. Alan Stocker of the University of Pennsylvania and his former graduate student Xue-Xin Wei, now a postdoc at Columbia University, have discovered a new such law, one of only a handful in existence. The researchers confirmed a link between how sensitive people are to changes occurring in front of them, what's called the discrimination threshold, and the perceptual bias, or the amount perception deviates from reality. They published their findings in the Proceedings of the National Academy of Sciences . To understand the new connection, Stocker suggests considering a wall that's uniformly lit. An experimenter changes the brightness of the light ever so slightly, then a little more and a little more. "The discrimination threshold tells us how fine the experimenter can actually change the light levels such that we still cannot detect it," said Stocker, an associate professor of psychology.