Growing up, Roberto S. Luciani had hints that his brain worked differently than most people. He didn’t relate when people complained about a movie character looking different than what they’d pictured from the book, for instance.

But it wasn’t until he was a teenager that things finally clicked. His mother had just woken up and was telling him about a dream she had. “Movielike,” is how she described it.

“Up until then, I assumed that cartoon depictions of imagination were exaggerated,” Luciani says, “I asked her what she meant and quickly realized my visual imagery was not functioning like hers.”

That’s because Luciani has a condition called aphantasia — an inability to picture objects, people and scenes in his mind. When he was growing up, the term didn’t even exist. But now, Luciani, a cognitive scientist at the University of Glasgow in Scotland, and other scientists are getting a clearer picture of how some brains work, including those with a blind mind’s eye.

In a recent study, Luciani and colleagues explored the connections between the senses, in this case, hearing and seeing. In most of our brains, these two senses collaborate. Auditory information influences activity in brain areas that handle vision. But in people with aphantasia, this connection isn’t as strong, researchers report November 4 in Current Biology.

While in a brain scanner, blindfolded people listened to three sound scenes: A forest full of birds, a crowd of people, and a street bustling with traffic. In 10 people without aphantasia, these auditory scenes create reliable neural hallmarks in parts of the visual cortex. But in 23 people with aphantasia, these hallmarks were weaker.

The results highlight the range of brain organizations, says cognitive neuroscientist Lars Muckli, also of the University of Glasgow. “Imagine the brain has an interconnectedness that comes in different strengths,” he says. At one end of the spectrum are people with synesthesia, for whom sounds and sights are tightly mingled (SN: 11/22/11). “In the midrange, you experience the mind’s eye — knowing something is not real, but sounds can trigger some images in your mind. And then you have aphantasia,” Muckli says. “Sounds don’t trigger any visual experience, not even a faint one.”

The results help explain how brains of people with and without aphantasia differ, and they also give clues about brains more generally, Muckli says. “The senses of the brain are more interconnected than our textbooks tell us.”

The results also raise philosophical questions about all the different ways people make sense of the world (SN: 6/28/24). Aphantasia “exists in a realm of invisible differences between people that make our lived experiences unique, without us realizing,” Luciani says. “I find it fascinating that there may be other differences lurking in the shadow of us assuming other people experience the world like us.”