The term originated in 1938 by the sociologist Willard Waller in his book The Family: A Dynamic Interpretation.
Throughout his research Waller found that power in a dating couple is almost never equally distributed between the two participants.
The first major study to test the principle came in 1972 in a paper by Kenneth Eslinger, Alfred D Clarke and Russell R Dynes.
[1] In the paper the researchers interviewed 113 randomly selected college students that were enrolled in sociology courses to find out if a difference in emotional involvement existed in relationships and whether or not the level of involvement was affected by how the person was raised.
In 1994 a study[4] of 413 heterosexual American adults found correlations between the power balance between the partners and the emotional involvement of them to be both negative and significant.
The study found that the partner less emotionally involved typically made the decisions about how to handle the couple's birth control.
While typically the principle of least interest is used in sociology to describe relationships, it has also been used to explain business deals.