How much free will do humans really exercise? Philosophers, theologians, scientists, and ethicists have been discussing this question since those disciplines were first practiced. Whether you believe we have unlimited free will, or believe we are prisoners of our genes and life circumstances, it is evident to most people living in the 21st Century that the structure of our brain plays a role in determining what we can or cannot do. If I put my hand on a hot stove, my brain is going to scream at me to remove it, no matter how much I want to prove how much free will I can exercise.
What about something as basic to human interaction as the decision whether to lie or to tell the truth? Is it a straightforward question of integrity? Is it a fully rational decision made by the conscious mind? Or is there some area of the brain that calculates costs and benefits?
A recent research project explored the part of the brain which is active during decisions about telling the truth or lying. It is called the dorsolateral prefrontal cortex, and it is located directly behind the forehead.
I frequently read the abstracts of studies on current scientific research. Even if the topic, and the study itself, is over my head, the abstract, or the openings paragraphs in the study, can often give me a clear idea of the findings. Then, if the findings are interesting enough to me, I can try to slog through the more detailed parts of the study.
This morning I was reading the website Science Daily, which aggregates science news. One of the articles was Possible neurological basis for the tradeoff between honesty, self-interest.
The article reported on a study by Lusha Zhu, Adrianna C Jenkins, Eric Set, Donatella Scabini, Robert T Knight, Pearl H Chiu, Brooks King-Casas, and Ming Hsu at Virginia Tech's Carilion Research Institute. Their results ran in the journal Nature Neuroscience, with the title Damage to dorsolateral prefrontal cortex affects tradeoffs between honesty and self-interest.
Here's an excerpt from the Carillon Institute's web page, describing the specific question the researchers were trying to answer:
“We prefer to be honest, even if lying is beneficial,” said Lusha Zhu, the study’s lead author and a postdoctoral associate at the Virginia Tech Carilion Research Institute, where she works with Brooks King-Casas and Pearl Chiu, who are assistant professors at the institute and with Virginia Tech’s Department of Psychology. “How does the brain make the choice to be honest, even when there is a significant cost to being honest?”
Previous studies have shown that brain areas behind the forehead, called the dorsolateral prefrontal cortex and orbitofrontal cortex, become more active during functional brain scanning when a participant is told to lie or to be honest.
But there’s no way to know if those parts of the brain are engaged because an individual is lying or because he or she prefers to be honest, King-Casas said.
This time, researchers asked a different question.
“We asked whether there’s a switch in the brain that controls the cost and benefit tradeoff between honesty and self-interest,” Chiu said. “The answer to this question will help shed light on the nature of honesty and human preferences.”
Their findings indicate that such a switch does indeed exist, and that damaging the switch can affect behavior:
We found that lesions of the human dorsolateral prefrontal cortex (DLPFC) decreased the effect of honesty concerns on behavior in economic games that pit honesty motives against self-interest, but did not affect decisions when honesty concerns were absent. These results point to a causal role for DLPFC in honest behavior.
I'm very fond of the notion that I can sit down, decide on a course of action, and carry out my decision by sheer exercise of will power. And I believe that we have significant leeway in making choices in our lives. I also think we can train ourselves to exhibit virtuous behaviors like honesty, But studies like the one at Virginia Tech help us understand the biological limitations we are working with. Decisions about truth and honesty, right and wrong, involve many physical processes in our brain, some of which are in our direct control, and others which go on behind the scenes.