Robert Bolesław Zajonc (/ˈzaɪ.ənts/ ZY-ənts; Polish: [ˈzajɔnt͡s]; November 23, 1923 – December 3, 2008) was a Polish-born American social psychologist who is known for his decades of work on a wide range of social and cognitive processes. One of his most important contributions to social psychology is the mere-exposure effect. Zajonc also conducted research in the areas of social facilitation, and theories of emotion, such as the affective neuroscience hypothesis. He also made contributions to comparative psychology. He argued that studying the social behavior of humans alongside the behavior of other species, is essential to our understanding of the general laws of social behavior. An example of his viewpoint is his work with cockroaches that demonstrated social facilitation, evidence that this phenomenon is displayed regardless of species. A Review of General Psychology survey, published in 2002, ranked Zajonc as the 35th most cited psychologist of the 20th century. He died of pancreatic cancer on December 3, 2008 in Palo Alto, California. Biography Early life Zajonc, born in Łódź, Poland on November 23, 1923, was the only child of the family. In 1939, before the Nazi invasion of Poland reached Łódź, his family fled to Warsaw. During their short stay, the building they were living in was hit by an air raid. Both of Zajonc's parents were killed, and he was seriously injured. The rest of his time in Warsaw was dedicated to studying at an underground university in Warsaw until he was sent to a German labor camp. He escaped from the work camp, got recaptured, and then sent to a political prison in France. After escaping for the second time, he joined the French Resistance, continuing his studies at the University of Paris. In 1944, he moved to England where he became a translator for the American forces during their European Campaign. Career After the end of World War II, he immigrated to the United States, where he applied for undergraduate admission at the University of Michigan. Under probation, he was accepted. In 1955, he received his Ph.D. from the University of Michigan, where he was a professor for nearly four decades, until 1994. During his time there, he held the positions of Director for the Research Center of Group Dynamics in the 1980s and Director of the Institute for Social Research in the 1990s. He then became Professor Emeritus of Psychology at Stanford University. Personal life and death