Psychologists utilize personality characteristics like extroversion, neuroticism, or anxiety to describe normal thought, emotion, and behavior patterns that vary from person to person. According to this viewpoint, a group of features that are difficult to modify and rather stable make up personality traits.
However, during the past two decades, there has been some debate on the presumption that these characteristics can be consistently measured using questionnaires that determine typical behavior. Not only do behavioral changes occur often, but they also do so hour by hour and day by day. Someone might be friendly and accommodating at noon but pessimistic and strict at two. Such fluctuations in day-to-day emotions and behavior, referred to as intraindividual variability.
When Peter C. M. Molenaar, an emeritus professor of human development and psychology at Pennsylvania State University, advocated for IIV in a manifesto titled “Bringing the Person Back into Scientific Psychology, This Time Forever,” the name for this new subject first appeared. He mocked conventional approaches to psychological testing while demonstrating the degree of dynamic flux in personality using a series of math and physics computations.
After the release of Molenaar’s manifesto, this perspective on the significance of IIV has only grown in popularity. It has helped us understand personalities better and changed some treatment techniques. Researchers have discovered that individuals respond differently to stressful daily situations, such as fighting with their spouse or getting stuck in traffic—can yield important insights about people’s long-term emotional and physical health.
