William James, the founder of modern psychology, wrote in 1890 that "everyone knows what attention is."

But 110 years later, the debate over exactly how the brain decides where to focus its visual energies continues to flourish.

A new study published this month in the journal Nature by scientists from the Harvard Vision Sciences Laboratory and Rutgers University supports the idea that the brain breaks up the visual field into discrete objects and catalogues all the properties of each object together.

Alex O. Holcombe, the Harvard member of the research team, explains the findings by waving his ballpoint pen in the air.

The experiments show, he explains, that if an observer looks at the pen and tries to focus only on the "Papermate Fine Point" label and not the rest of the pen, he cannot. The brain perceives the pen as a distinct object and notes all of its properties together--whether people like it or not.

"You process all of the pen, not just the color of it...not just the writing part, even though you may not want to do that," Holcombe says.

The team's discovery is the latest development in decades of research on how just how people select certain bits of visual information for special attention.

When subjects in psychology experiments are asked to pay attention to one visual cue and ignore everything else, dramatic results can take place.