In the study, monkeys were given the task of searching for one particular tilted, colored bar among a field of bars on a computer screen.
By monitoring the activity of neurons in three of the animals' brain regions, researchers found that the monkeys spontaneously shifted their attention in a sequence, like a moving spotlight that jumped from location to location.
The study also showed that brain waves act as a kind of built-in clock that provides a framework for shifting attention from one location to the next.
The work could have implications for understanding or treating attention deficit disorder or even potentially speeding up the rate of cognition in the brain.
"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. Ours is the first study based on direct evidence of neurophysiological activity," said lead author Earl K. Miller, the Picower Professor of Neuroscience.
The researchers also found that the spotlight of the mind's eye shifted focus at 25 times a second and that this process of switching was regulated by brain waves.
"This is one of the first examples of how brain waves play a specific role in cognitive computations," said Picower Institute postdoctoral associate and co-author Timothy J. Buschman.
Miller said: "Attention regulates the flood of sensory information pouring into the brain into a manageable stream. 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. 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," Miller added.
The researchers' next step is to expand their search for brain wave function beyond the visual. They hope to discover whether brain waves are specific to visual function or act as a "general clock" for the brain.