When you're searching for a friend in a crowd, it appears that your "mind's eye" acts like a spotlight to scan the scene in front of you until you find the right person.
Researchers from the Massachusetts Institute of Technology monitored the brain activity of monkeys as they searched for a specific tilted, colored bar among a field of bars on a computer screen. The results showed that the monkeys spontaneously shifted their attention in a sequence, like a spotlight that moved from location to location.
The study also found that brain waves act like a form of built-in clock that times the shifts in attention from one location to the next. The mind's eye spotlight in the monkeys shifted focus at a rate of 25 times a second.
The findings could help improve understanding and treatment of attention-deficit disorder or could lead to ways to increase the rate of cognition in the brain, according to the researchers, who were from MIT's Picower Institute for Learning and Memory.
"For many years, neuroscientists have been debating competing theories on whether humans and animals spontaneously search elements of a visual scene in a serial or parallel manner," study author Earl K. Miller, a professor of neuroscience at MIT, said in an MIT news release. "Ours is the first study based on direct evidence of neurophysiological activity."
"Attention regulates the flood of sensory information pouring into the brain into a manageable stream," Miller said. "In particular, a lot of different areas of the brain are involved in vision. If they all competed at once, it would be chaos."
"Brain waves may provide the clock that tells the brain when to shift its attention from one stimulus to another," he said. "Oscillating brain waves may provide a way for several regions across the brain to be on the same page at the same time -- very similar to the way computers use an internal clock to synchronize the many different components inside."
A report on the findings appears in a recent issue of Neuron.
- Robert Preidt