Extraordinary Perception Deficit Sheds Light on How We See

Office of News and Information - Johns Hopkins University - 901 South Bond Street, Suite 540 - Baltimore, Maryland 21231 - Phone: 443-287-9960 | Fax: 443-287-9920 To the casual observer, the student seemed absolutely normal. Though she often made mistakes in spelling and math, those were usually ascribed to carelessness. After all, the girl — known here as "AH" to protect her anonymity — was a top student in history at The Johns Hopkins University. In reality, though, AH had an extraordinary deficit in visual perception that caused her often to see objects on the opposite side from where they actually were. It was a deficit that Michael McCloskey , professor of cognitive science at Johns Hopkins, discovered when working with the student back in the late 1990s. "When AH looks at an object, she sees it clearly and knows what it is, but she's often dramatically wrong about where it is," said McCloskey, who has spent years studying AH's fascinating case. "For example, she may reach out to grasp a coffee cup that she sees on her left, but miss it completely because it is actually on her right.