Turning away customers looking for an afternoon jolt of caffeine, 8,000 Starbucks shops across the U.S. began closing up early on Tuesday to hold training for 175,000 employees on recognizing hidden prejudices.

It was part of the coffee chain’s effort to deal with the outcry over the arrest of two black men last month for sitting in a Philadelphia Starbucks without buying anything.

Self-described loyal Starbucks customer Darnell Metcalf, a 55-year-old black man from Miami, said he was dubious about how much a four-hour training session might accomplish for employees “raised to look at certain people a certain way and act a certain way.”

And he said the problem is not confined to Starbucks but exists at plenty of other retail chains where he has seen people profiled.

“It makes it look like they’re trying to, you know, quiet the storm,” Metcalf said outside a closed-for-training Starbucks. “They’re not solving nothing. They’re not going to fix this overnight. … It’s not Starbucks the corporation. It’s only certain employees who are like that.”

Starbucks has not said how much the training will cost the company or how much money it expects to lose from closing the stores during what is usually its least busy time of day.

“It’s quite expensive,” Chairman Howard Schultz said Tuesday. “We’ve had certain shareholders call and say, ‘How much is this going to cost and how do you justify this?’ My answer to them was simply: We don’t view it as an expense. We view it as an investment in our people and the long-term cultural values of Starbucks.”

At the company’s famous Pike Place Market location in Seattle, commonly referred to as the original Starbucks, the store stopped letting people in at 1 p.m.

Trina Mathis, who was visiting from Tampa, Florida, was frustrated that she couldn’t get in to take a photo but said the shutdown was necessary because what happened in Philadelphia was wrong.

“They need to … try to do all they can to make sure their employees don’t make that same mistake again,” said Mathis, who is black.

The training in unconscious, or implicit, bias was not mandatory, but Starbucks said it expected almost all of its employees to participate. It said they will be paid for the full four hours.