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Robert Bolesław Zajonc (// ZAY-ənts; 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.
Early life 
Robert Boleslaw Zajonc, an only child, was born in Lodz, Poland on November 23, 1923. In 1939, before the Nazi invasion of Poland reached Lodz, 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 died, and he was seriously injured. The rest of his time in Warsaw was dedicated to studying at an underground university, until he was sent to a German labor camp. He escaped the work camp, was 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 became a translator for the American forces during their European Campaign.
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 PhD from the University of Michigan, where he was a professor there for nearly four decades, until 1994. During his time there, he held the positions of Director of the Institute for Social Research and Director for the Research Center of Group Dynamics. He then became Professor Emeritus of Psychology at Stanford University.
Mere Exposure Effect 
One important contribution was the demonstration of the mere exposure effect, the phenomenon that repeated exposure to a stimulus brings about an attitude change in relation to the stimulus. He focused on processes involved in social behavior, with an emphasis on the relationship between affect, or emotion, and cognition. For example, he found that participants reacted more favorably toward the nonsense words zebulons and worbus through repeated exposure.
Social facilitation 
Zajonc was also well known for demonstrating how social facilitation (how the presence of others increases or decreases performance) works in humans and other animals, notably in cockroaches, which indicated that social facilitation is not entirely the result of higher cognitive processes.
Confluence Model 
Zajonc, along with Greg Markus, developed the Confluence Model (1975), which provided a mathematical model of the effect of birth order and family size on IQ scores. This theory suggests that children are born into intellectual environments that affect intelligence—first born children are born into adults-only families, all others are born into mixed adult/child families. As families increase in size, the overall IQ of the family drops; children from larger families do have slightly lower IQs. The last child in the family is denied the opportunity to tutor younger children, and there is a slight "extra" decrement for being the youngest child in a family. These effects are theoretically important, but the size of the effects is fairly small (amounting to a range of about 3 IQ points)
Empathy and Facial Features 
Robert Zajonc and a group of his colleagues did a study to try and evaluate how couples who have been together for 25 years (i.e. married couples) begin to develop similar facial features. The study involved 110 participants (55 couples) whose photographs were taken in their first year of marriage. The participants were also asked what they thought the chances were of looking like their spouses 25 years later. The majority of the description of changes that the participants anticipated was mostly facial. Twenty-five years later when the new photos were taken, the results could not be explained by simply comparing the images, but by the fact that each couple believed that their facial features actually changed and looked similar to their spouses. Zajonc and his colleagues developed numerous explanations for how such a phenomenon could happen. Three explanations that were ruled out as possibilities were similar diets, environmental influence, and conscious selection. High fat diet making each spouse face chubby was ruled out because not all the participants were chubby. Since all the couples came from the same part the US Midwest they were able to rule out environment as a factor. The thought of people picking a spouse that will most likely grow old to look similar to each other wasn’t ruled out completely, but predisposition wasn’t the best reason. The explanation the scientists agreed on was empathy. Most married couples who have been together for 25 years or longer can identity with the other persons feelings. A lot of human emotions and feelings are expressed through the face, and when two people make similar facial expressions for 25 years it could result in similar wrinkle patterns. There isn't enough evidence to prove this theory to be completely true, but it is definitely a possibility.
Preferences Need No Inferences 
In 1980, a speculative and widely-argued paper entitled "Feeling and Thinking: Preferences Need No Inferences," invited in honor of his receipt of the 1979 Distinguished Scientific Contribution Award from the American Psychological Association, made the argument that affective and cognitive systems are largely independent, and that affect is more powerful and comes first. This paper precipitated a great deal of interest in affect in psychology, and was one of a number of influences that brought the study of emotion and affective processes back into the forefront of American and European psychology.
Zajonc was married to American social psychologist Hazel Rose Markus, known for her contributions to cultural psychology.
See also 
- Audience effect ("in subjects ranging from cockroaches to humans")
- Facial feedback hypothesis
- Sydney Symposium of Social Psychology
Selected bibliography of Zajonc's work 
This is a partial bibliography of Zajonc's works in English.
- 1965. Social facilitation. Science, 149, 269-274.
- 1966. Social facilitation of dominant and subordinate responses. Journal of Experimental Social Psychology, 2(2), 160-168.
- 1968. Attitudinal effects of mere exposure. Journal of Personality and Social Psychology, 9(2, Pt. 2), 1-27.
- 1975. Birth Order and Intellectual Development, with G. Markus. Psychological Review, 82, 74-88.
- 1980. Feeling and thinking: Preferences need no inferences. American Psychologist, 35(2), 151-175.
- 1982. Affective and cognitive-factors in preferences, with H. Markus. Journal of Consumer Research, 9(2), 123-131.
- 1984. On the primacy of affect. American Psychologist, 39(2), 117-123.
- Fox, Margalit (2008-12-07). "Robert Zajonc, Who Looked at Mind's Ties to Actions, Is Dead at 85". The New York Times. Retrieved 2010-05-22.
- Kenrick, Neuberg, & Cialdini, . Social Psychology. 5ed. Pearson, 2009. Print.
- Esping, Amber. "Does Birth Order Affect Intelligence". Human Intelligence. Indiana University. Retrieved 27 January 2013.
- "Stanford Psychology Department - Faculty - Robert B. Zajonc". Stanford University web site. Archived from the original on 2008-01-24. Retrieved 2008-12-04.
- "Professional Profile: Robert Zajonc". Social Psychology Network web site. Retrieved 2008-12-04.
- "Obituary". University of Michigan web site. Retrieved 2009-10-11.