Origins and Consequences of Individual Differences

The History and Legacy of Psychology at Minnesota

Psychology at Minnesota is well-known for its rigorous commitment to the study of individual differences. When psychologists speak of 'individual differences' they are referring to a set of variables, e.g. personality traits held by all humans, across many cultures - that vary in expression from one individual to another. The “Big 5” traits of personality psychology are examples of well-known dimensions.  Although the field of psychology’s long-standing commitment to understanding individual differences has not been without controversy, scientific consensus as of the beginning of the 21st century indicates that Minnesota has been on the right path with regard to its approach.  Minnesota is now positioned as a leader in numerous fields in which individual differences are a key aspect, such as the applied fields of psychology, personality psychology and behavioral genetics, cultural psychology, as well as clinical science and psychopathology.  

Read more about how our faculty contribute to this area of excellence:


The study of individual differences is rooted in the idea that human beings differ in meaningful ways and that these differences are relatively stable, reliably predictable, measurable, and quantifiable.  Between WW2 and the 1970s, numerous psychologists at Minnesota became well-known internationally for screening individuals for different personality traits and then matching them with different job duties.  For instance, Donald Patterson supported the war effort through his troop screenings that supported the massive buildup of the armed forces in WW2; Lloyd Lofquist in counseling psychology and Marvin Dunnette in industrial and organizational psychology became similarly influential through using screenings in their respective areas; and, of course, Starke Hathaway's Minnesota Multiphasic Personality Inventory (MMPI) has been an enduring testament to the importance of the study of individual differences in clinical and other settings.

In the 1960s and 1970s, Paul Meehl in collaboration with many Department psychologists began to consider questions of psychopathology from the perspective of individual differences and genetics.  Famously, Meehl noted that schizophrenia did not occur randomly and that the data indicated that the disease was heritable.  Nevertheless, some members of families became afflicted with the illness while others did not.  Did certain individual traits make some individuals more resilient, and others more susceptible?  Psychology's strength in individual differences expanded significantly when in the 1980s, David Lykken and others established what we now know as the Minnesota Center for Twin and Family Research.  Studying twins is of course one natural experiment that allows researchers to pose and answer questions about genetic and environmental contributions to human individual differences.  The emphasis on empiricism, evidence, and data in the study of human behavior are all hallmarks of research that considers individual differences, and advances in genetic technologies (e.g. being able to sequence human genomes)  and computing power have only expanded the work in recent years.

Since the 1990s the study of individual differences has been subject to the same concerns as has much of the field:  a concern about the importance of reproducibility and a recognition of the importance of expanding research to include participants more diverse than only persons of European descent.  Faculty in the department have played a key role in this expansion, charting the similarities and differences in psychological phenomena both within and between racial, ethnic, and cultural groups. As the work has expanded, long-standing controversies have grown in relevance. One of the more controversial aspects of the individual differences tradition is the idea that intelligence is a trait that is difficult to modify and that IQ is a quantifiable feature that some individuals have in greater or less measure than others.  Researchers from a variety of perspectives are surmounting these challenges and contribute to ongoing debates and those yet to come.  Given our past successes and our willingness to engage constructively with current challenges, Minnesota remains a vibrant center for understanding individual differences in a scientifically rigorous and respectful manner.

Share on: