A rational agent can be anything that makes decisions, typically a person, firm, machine, or software.
Rational agents sometimes behave in manners that are counter-intuitive to many people, as in the traveler's dilemma.
Neuroeconomics is a concept that uses neuroscience, social psychology and other fields of science to better understand how people make decisions.
Unlike rational agent theory, neuroeconomics does not attempt to predict large-scale human behavior but rather how individuals make decisions in case-by-case scenarios.
Artificial intelligence has borrowed the term "rational agents" from economics to describe autonomous programs that are capable of goal directed behavior.