When Your Eyes Tell Your Hands What to Think

EVANSTON, Ill. --- Sixteen-year-old Shélan O’Keefe sat on the “L” train contemplating whether to attend one of Northwestern University’s Science Cafés for middle and high school students at the Evanston Public Library -- or just go home. She felt a bit under the weather, but the talk was about optical illusions, a topic she found fascinating.

O’Keefe decided to go, and she’s glad she did. Her observation during the question period sparked an idea for a research project, landed her a summer job at the university and, at age 18, made her a co-author of “Visual Influence on Haptic Torque Perception” published last week in the scientific journal Perception. 

Steven Franconeri, associate professor of cognitive psychology at Northwestern, gave the Science Café talk that day and later offered O’Keefe a research opportunity.

At the Science Café, Franconeri demonstrated a visual illusion where you can mentally ‘flip’ the direction you perceive an object facing.

“Imagine looking directly down into a paper cup,” Franconeri explained. “If you close one eye so that you are only seeing the world in 2D, it’s actually ambiguous whether the cup is upright or upside down. With a little practice, you can actually change which one you see. In the demonstration we used a wire champagne hood instead of a cup, but the idea is the same.”

But an observation by O’Keefe set the room abuzz with discussion. “When I hold the object in my fingers, and then I flip it in my head, I could swear that the weight actually shifts,” she said.

“Shélan brought a fresh perspective that allowed her to notice something that I assumed wouldn’t be possible,” Franconeri said. “I was anxious to test the idea and gather more evidence for her observation.”

After exchanging emails with O’Keefe in the following weeks, he offered her an opportunity to test her observation as part of a four-week research project in his lab. She worked alongside Yangqing “Lucie” Xu, a doctoral candidate in psychology.

Throughout the summer and into the fall, Xu and O’Keefe, who was then a homeschooled student, worked tirelessly on the project, designing and building dozens of devices that they might use to test her idea in the lab. 

In the end they used a vertical stick with a weight on one side, paired with a set of mirrors that could trick the observer into seeing the weight on the left, when it was actually on the right. The data neatly confirmed Shelan’s initial observation -- even when people were told to report on which side they felt the weight, they could not ignore what they saw, and often reported the opposite answer.

“When you pick up an object, your brain automatically decides how to control your muscles based on what your eyes provide about the object’s shape, ” said Xu, lead author of the study. “When you pick up a mug by the handle with your right hand, for example, you need to add a clockwise twist to your grip to compensate for the extra weight that you see on the left side of the mug.  

“But this visual information is so powerful and automatic that we cannot turn it off,” Xu said. “When people see an object weighted in one direction, they actually can’t help but ‘feel’ the weight in that direction, even when they know that we’re tricking them.”   

O’Keefe, as the second author on the paper, was an “indispensable” collaborator to Franconeri and Xu. Xu said she often forgot O’Keefe was a high school student with no prior lab experience. 

“She’s very self-motivated, passionate about science, and a quick learner,” Xu said. “She's an extremely creative and talented person -- an actor, musician, and artist on the side. That creativity was indispensible to the scientific testing, especially across the dozens of construction projects that it took to design the testing apparatus.”

These days, O’Keefe, who sings, writes song lyrics, plays guitar, drums and “a mean ukulele,” plans to enroll in college next fall, is busy researching and applying to colleges and planning campus visits. She’s not sure about a major just yet. She has many interests in addition to music, including acting and filmmaking, but has not ruled out a career in science.

“I’ve always romanticized being a scientist, and I thought that I would have to wait to do all this,” said O’Keefe. “This amazing experience gave me the confidence to go forward. It was very gratifying.”