Nobel Prize winner Daniel Kahneman, who pioneered theories in behavioral economics that heavily influenced the discipline, has died at age 90, his employer confirmed Wednesday.

Kahneman, who wrote best-selling book "Thinking, Fast and Slow," argued against the notion that people's behavior is rooted in a rational decision-making process — rather that it is often based on instinct.

Princeton University, where Israeli-American academic Kahneman worked until his death, confirmed his passing in a statement on its website.

"Many areas in the social sciences simply have not been the same since he arrived on the scene. He will be greatly missed," said former colleague and professor Eldar Shafir in a press release.

In 2002, Kahneman was awarded the Nobel Memorial Prize in Economic Sciences in recognition for his research in the fields of psychology and economics.

His most popular theory opposed traditional economic approaches that people were fully rational and self-interested. Instead, the theory argued that people have mental biases that can distort their judgments.