Penn researchers have discovered a new law of perception that helps to explain why people see the world the way they do. The new law links the discrimination threshold (measured by how sensitive people are to changes occurring in front of them) to the perceptual bias (the amount perception deviates from reality). The link was confirmed by Alan Stocker, professor of psychology in the School of Arts & Sciences and electrical and systems engineering in the School of Engineering & Applied Science, and his former graduate student Xue-Xin Wei, Gr’15, now a postdoc at Columbia University.

The researchers knew from a theory they developed several years ago that humans go through a two-step process to perceive a stimulus. Step one is encoding, the process by which the one absorbs information from the senses, filters the information and sends it to the brain. Step two is decoding, or “taking that signal and combining it with what we know about the world, intelligence, prior beliefs that get used to interpret this encoded signal in a way that makes sense,” according to Dr. Stocker. Research has established that the encoding step shapes the decoding step, but Drs. Stocker and Wei theorized the decoding might also influence the encoding. The next step was connecting the discrimination threshold and perceptual bias.

While no practical applications have been developed for the new perception law yet, it helps researchers develop a better idea of the importance of people’s previous experiences in shaping their perceptions.