DENVER (AP) -- Before he closes his book, San Francisco Giants outfielder Hunter Pence stares and stares at a card marking his page.
It's an eye exercise, designed to merge two 3D circles into one shape.
The task is trickier than it sounds, and Pence insists the endeavor helps him at the plate to decipher a tailing fastball from a nasty slider.
Just as Colorado third baseman Nolan Arenado believes playing pingpong sharpens his eye-hand coordination and his teammate Charlie Blackmon credits the video game ''Call of Duty'' for his sizzling start. Longtime major leaguer Ellis Burks even used to stare at a candle in a darkened room to visualize locking onto a target.
Anything to help catch up with a pitch that arrives in less time than it takes to say ''play ball.''
The baseball adage used to be ''see ball, hit ball.'' Really, though, it's more like ''see ball, recognize and identify the pitch, figure out if it's worth taking a swing at and then hit ball.''
Players generally have about two-tenths of a second - the blink of an eye - to decide whether to swing or not. The human eye really isn't fast enough to follow a 95 mph fastball from the pitcher's hand all the way to the plate.
''I've been around the game for 40 years, and it's almost unbelievable that hitters can actually hit the opposing pitchers pitches the way they do,'' said Dr. Bill Harrison, who works with numerous major and minor leaguers on improving their vision. ''It's a phenomenal capability.''
But there are plenty of creative ways to train the brain to ensure the bat is in the right place and the eyes are spotting the right pitch. Some methods are learned from watching veterans around the clubhouse, others through word of mouth.
As a young hitter, Giants outfielder Angel Pagan used to stare at tennis balls shot out of a machine at 120 mph. He would call out the numbers and colors painted on the tennis balls as they rocketed past him, an approach he first heard about through Mariners great Edgar Martinez and eight-time All-Star Carlos Beltran.
''Working your eyes like that will send a proper message to your brain so you can recognize a pitch a little bit quicker,'' Pagan explained.
When Philadelphia first base coach Juan Samuel was in the big leagues, he and Tony Fernandez used to pitch kernels of corn to each other and hit the seeds with a broomstick. They also spun beer caps at each other, just to get used to the spin.
They went through plenty of kernels and caps to hone their batting eye.
''If you get used to hitting these little kernels, then the baseball is going to look this big for you,'' Samuel said as he held out his hands about a foot apart. ''As much as we train our hands and everything, you've got to train your eyes.''
Harrison has been teaching vision techniques since he first worked with Hall of Famer George Brett. He believes vision training is almost a hidden secret, especially with hitters focusing so much on the biomechanics of a swing. He instructs young hitters - like Miami slugger Giancarlo Stanton - to follow the pitch all the way through to the catcher's glove.
''Because a hitter needs to see pitches before they can hit them. There's a stored visual memory of what a pitch looks like,'' Harrison explained.
For instance, a two-seam fastball leaving a pitcher's hand will have a spin pattern that resembles a railroad track and a slider has a red-spot appearance.
''As they begin to know what pitches look like, they then pick it up early and project what it's going to do,'' Harrison said. ''It goes from a visual process to a brain process. Our brain really is aware of things that we're not consciously seeing. It's like a subconscious vision.''
Eye-hand coordination is a big component, too, which is why Arenado enjoys pingpong. So does Seattle designated hitter Corey Hart.
Blackmon plays ''Call of Duty'' with teammate D.J. LeMahieu.
''Improves reaction time, making us better hitters,'' said Blackmon, who's tied for fifth in the NL with a .329 average. ''No game is ever the same and you make in-game adjustments, just like in baseball.''
Burks is a legend around the Rockies clubhouse, with Drew Stubbs and Michael Cuddyer talking reverently about him honing his skills by staring at a flickering flame for five minutes in the dark. Burks said the routine - learned from a yoga instructor - bolstered his concentration.
''After staring at a candle, you can really lock onto a target,'' said Burks, who spent 18 years in the big leagues.
This helps, too: confidence.
''It's weird, because when you're feeling good at the plate and seeing the ball well, you recognize those pitches right away,'' Stubbs said. ''But when you're scuffling, you don't seem to see the spin at all.
''The more confidence you have, the more you can slow the ball down, track it and recognize it.''
AP Baseball Writer Janie McCauley in San Francisco and AP freelancer Ian Harrison in Toronto contributed to this report.