Certain people, researchers have discovered, can’t summon up mental images — it’s as if their mind’s eye is blind. This month in the journal Cortex, the condition received a name: aphantasia, based on the Greek word phantasia, which Aristotle used to describe the power that presents visual imagery to our minds.

I find research like this irresistible. It coaxes me to think about ways to experience life that are radically different from my own, and it offers clues to how the mind works.

And in this instance, I played a small part in the discovery.

In 2005, a 65-year-old retired building inspector paid a visit to the neurologist Adam Zeman at the University of Exeter Medical School. After a minor surgical procedure, the man — whom Dr. Zeman and his colleagues refer to as MX — suddenly realized he could no longer conjure images in his mind.

Dr. Zeman couldn’t find any description of such a condition in medical literature. But he found MX’s case intriguing. For decades, scientists had debated how the mind’s eye works, and how much we rely on it to store memories and to make plans for the future.