Faith, Truth and Forgiveness: How Your Brain Processes Abstract Thought

Researchers at Carnegie Mellon University have leveraged machine learning to interpret human brain scans, allowing the team to uncover the regions of the brain behind how abstract concepts, like justice, ethics and consciousness, form. The results of this study are available online in the October 29 issue of Cerebral Cortex.

"Humans have the unique ability to construct abstract concepts that have no anchor in the physical world, but we often take this ability for granted," said Marcel Just, the D.O. Hebb University Professor of Psychology at CMU's Dietrich College of Humanities and Social Sciences and senior author on the paper. "In this study, we have shown that newly identified components of meaning used by the human brain that acts like an indexing system, similar to a library's card catalog, to compose the meaning of abstract concepts." 

The ability of humans to think abstractly plays a central role in scientific and intellectual progress. Unlike concrete concepts, like hammer, abstract concepts, like ethics, have no obvious home in the parts of the brain that deal with perception or control of our bodies.

"Most of our understanding of how the brain processes objects and concepts is based on how our five senses take in information," said Robert Vargas, a CMU graduate student in Just's lab and first author on the paper. "It becomes difficult to describe the neural environment of abstract thoughts because many of the brain's mental tools to process them are themselves abstract."

In this study, Just and his team scanned the brains of nine participants using a functional MRI. The team sifted through the data using machine learning tools to identify patterns for each of the 28 abstract concepts. They applied the machine learning algorithm to correctly identified each concept (with a mean rank accuracy of 0.82, where chance level is 0.50).

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