Picture yourself as a sleeper agent in a foreign capital. Everyday you go to your sham job amid a throng of other commuters. You’ve done this for months, but one day you begin to notice that a particular face trailing behind you no longer just blurs into the crowd as it had for who knows how long. It’s now familiar and easier to perceive. That’s the moment you realize you’ve been “made.” You are being followed. They know who you are and you’d better get out.
Terrifying? For your imaginary self, sure, but to Takeo Watanabe, professor of cognitive, linguistic, and psychological sciences, your little leap in perceptual acuity would be just another data point. An expert in visual perception, he studies the means by which it improves. This is called perceptual learning.
“I’m interested in how we can learn to have a better sensitivity to visual stimuli,” he said. “I’m interested not only in how we can learn to develop that higher sensitivity, but also in how the brain can let us do that.”
Eyes take in light and process it a bit, but the brain is really the organ that sees because seeing is about significance. We perceive what we think is important.
Until about a decade ago, scientists were mostly convinced that perceptual learning required intense and intentional attention. Learning to distinguish very subtle differences, they thought, could only happen when you concentrated on them. In an October 2001 paper in Nature, Watanabe showed that such focus wasn’t necessary at all. His experiments at Boston University showed that the brain will catch on to a stimulus, even when it is virtually invisible and totally irrelevant, after it has seen it enough times.
“If a weak stimulus is presented again and again, that can make your brain think that the stimulus is important,” he said. “Important information is usually repeated.”
Because perception is a rather fundamental capability, it’s no surprise that studies of perceptual learning have intriguing applications. One of the research questions Watanabe is asking right now amid the transition from Boston University to Brown is whether controlled exposure to purposely blurred letters can help aging readers get ahead of the degradation in their vision. Can people train themselves to more easily distinguish among the blurry characters?
“Reading defocused letters is to [distinguish between the] right letters and noises,” Watanabe said. “Through perceptual learning we can remove some amount of noise in the brain so that we can learn to read better.” Initial results are not yet published but seem promising, he said.
Watanabe is bringing other projects with him to Brown, too, including four National Institutes of Health-funded investigations into fundamentals of perceptual learning. One is to tease out the factors important to efficient learning. Another is to establish a sleep lab to determine why slumber appears to strengthen perceptional learning. Another is to test how perceptual learning occurs with older people’s brains. Finally, he will look at the underlying mechanisms and changes in the brain, as measured with functional magnetic resonance imaging, that make perceptual learning happen.
The availability of Brown’s fMRI machine in Sidney Frank Hall was one of the enticements that convinced Watanabe to come down I-95 from BU. At Brown, fMRI is on the main campus; at Boston University it was in a medical school that is remote from the main campus.
A variety of other factors also influenced Watanabe to move his research and teaching here. Among them is the chance to work with Brown’s undergraduate students.
“Brown undergraduates are very special and very bright,” he said. “I expect them to collaborate with me.”
And, of course, he expects them to be his students. At Boston University he taught a general course in perception, but amid a community of vision scientists at Brown he’ll be able to teach more specific advanced classes such as one about consciousness in relation to visual and cognitive processing from a neuroscientific viewpoint.
That should be one class where students will understand the benefit of keeping their eyes front during the lecture. If they see a concept presented repeatedly, they can bet it’s important.