Sometimes it’s literally a glob of grease, other times it’s a synthetic sticker. We’ve all seen baseball and football players with the black rectangles under their eyes on sunny days, which is thought to help reduce the sun’s glare and allow athletes to better pick up the ball. But does it actually work?
The underlying concept behind eye black is that it reduces the amount of glare that reaches your eyes thanks to the fact that the color black absorbs most light frequencies. In theory, excessive light from sources in our peripheral vision will be absorbed by the black color, increasing the contrast of the objects we're are looking at and focusing on directly.
There have been a handful of studies done in the past decade, including one by the University of New Hampshire and one by Yale University. Although these two and others began with skepticism and have all yielded slightly different results—while accounting for the effect of variables such as eye color and gender—they have agreed that traditional eye grease made of beeswax, paraffin, and carbon does in fact reduce glare and improve contrast sensitivity. They also all concluded that anti-glare stickers and petroleum jelly have no impact.
“I thought we would find it to be like war paint and a psychological advantage more than anything else,” Dr. Brian M. DeBroff, the lead author of the Yale study, told The New York Times. “We were surprised to find a benefit from the grease.”
Even though the effect was found to be somewhat minimal, DeBroff has adopted somewhat of an “it can’t hurt” stance regarding its application to high-intensity sport situations.
“Certainly in football and baseball, where tracking a ball at high speed is an important aspect, any competitive advantage could be beneficial,” DeBroff said.
Despite this, researchers are still unsure how much impact the glare reduction and contrast improvement translates into an “on-the-field” advantage for athletes. Dr. Kenneth Fuld, chairman of the University of New Hampshire’s psychology department and the sponsor of the aforementioned study conducted by the university, points out that tennis players regularly perform at a high level despite the fact that they do not wear eye black.
“I would be highly doubtful that it would have much of an effect, if any,” Fuld said.
Although it is extremely reasonable to conclude that it is a coincidence, it is interesting to note that last year’s two top NFL receivers in terms of receiving yards, Calvin Johnson of the Detroit Lions and Andre Johnson of the Houston Texans, both regularly wear eye black during games.