How much of our decision making is controlled by rational thought, and how much is determined by more primitive brain structures? How do we rationalize decisions based on the latter? What motivates our decisions?

These and other difficult questions were addressed at the symposium moderated by Harvard Medical School (HMS) Professor of Psychiatry Paul Barreira Friday titled “Decisions, Decisions: Health, Wealth, Happiness, and Neurobiology.”

Marc Hauser, co-director of the Mind, Brain, and Behavior Initiative, talked about how researchers are using observations of both primates and children — as well as transcranial stimulation and other high-tech processes — to tease out differences between innate and culturally determined decision making.

Professor of Economics David Laibson said that economists used to consider human beings “rational actors making perfect decisions.” Now, researchers ask how the brain is involved in economic decision making. MRIs have shown that people respond similarly to rats and monkeys when confronted with near-future versus delayed rewards: “If I get it now, it counts. If I get it in a week, I don’t care.” He compared the rational and primitive parts of the human brain to the proverbial angel and demon on one’s shoulders, and noted that heeding the wrong one can “lead us down … self-defeating paths.”

Jerome Groopman of HMS and the Beth Israel Deaconess Medical Center, turned the conversation from economics to medicine. Groopman, author of “How Doctors Think,” said that several years ago while doing rounds with interns, he noticed that “all too often these bright, motivated, affable trainees were not thinking deeply,” but were “quick to seize on the first bit of information offered,” often because of their easy access to technology. It suddenly occurred to him that, “I wasn’t really sure how I thought as a physician. If I didn’t understand that, how could I teach them?”

He found that doctors are “not rational operators,” but also learned that “it’s not beneficial to always be rational.” There are times, for example, when the art of medicine can get lost in the science of technology.

Linda Hill, faculty chair of the Leadership Initiative at Harvard Business School (HBS), discussed the case-study approach taken at HBS, saying, “Many people believe leaders are born, not made — but research suggests otherwise.” One of the most important things to teach business students is “not to focus on decision making but on a sense of moral agency and courage.”

Sue Goldie — a professor of health decision science at the Harvard School of Public Health (HSPH) — took a more global view of decision making, using the examples of maternal death and cervical cancer in the developing world to discuss the “complexity, uncertainties, multiple competing objectives, and trade-offs in public health.”

Inequality and justice, why, where, when, who