The hoop is anchored to her body; it doesn’t move if she tilts or rotates her head. “Obviously, this is a construct in her head, not a real hula hoop stuck to her chest,” says Ramachandran. But if she turns her head to the right, the left side of the calendar became fuzzier, as it would be if it was an actual physical object. More bizarrely, the memories that she had appended to those months also became indistinct and harder to recall.
To Ramachandran, this beautifully illustrates a concept called “embodied cognition,” which says that the way we think isn’t just the product of our brains, but is also profoundly influenced and constrained by our bodies. In this case, Emma’s neck and eye muscles are effectively opening and shutting the gates to at least some of her memories. “It’s one of the most striking examples of embodied cognition that I know of,” Ramachandran says. “And it provides strong hints that [the calendar form] is a legitimate biological phenomenon.
Then again, much of this relies on Emma’s own testimony. So when Ramachandran met a second woman with a calendar form, a 20-year-old named Megan, he did some experiments. Her calendar is a mirror-image check mark, with January on the top-left corner, September at the bottom, and December on the top-right.
First, Ramachandran asked Megan to name the months of the year backwards from a random starting point. Most people find this task harder than they expect—they hesitate, or make mistakes. But Megan was much faster than average, even on more difficult variations like skipping every other month, or two months at a time. She was actually reading the months off her calendar: Ramachandran filmed her shifting her gaze to the right positions and sometimes moving her index finger too.
“These results show the calendar is not some vague figment of her imagination,” he writes. “It is vivid enough to enhance performance on a cognitive task that is difficult for non-synesthetes.” (When I tried the test he said, “You’re better than most regular people but still about half Megan’s speed.”)
Rosa Rugani from the University of Padova is intrigued by the case, but notes that Ramachandran asked Megan to draw out her calendar before the test. “It’s possible that the effort in drawing the calendar, which requires visualizing it, might have helped in the task,” she says.
That said, Ramachandran found that Megan’s calendar is also vulnerable to visual illusions. For example, if you stare at a contracting spiral for several seconds and then look at another object, it will seem to expand. That illusion won’t work if you just imagine an object on a white screen; you have to be looking at a real thing. And indeed, when Megan visualized her check-mark-shaped calendar on a screen, it did expand, behaving like a real object.
Here’s another illusion. When old-fashioned TV screens lost signal, they’d show snow—black dots on a white background. If you put a black rectangle over the screen, the dots within that shape seem to clump together and move more slowly. And if you move the black border, the dots within seem to get dragged along. And that’s exactly what Megan saw when she visualized her calendar on top of a display of electronic snow.