In fact, when riot shields are raised, the seemingly simple fact that civilians can’t see the cops’ faces flips a psychological switch for some citizens in the crowd — and that image acts to dehumanize the officers, said Norm Stamper, who served as chief of the Seattle Police Department during the 1999 WTO riots.

“It makes a huge difference. We are social creatures, we are human beings. We need to see people’s eyes and we need to see people’s expressions,” said Stamper, who worked 34 years in uniform and holds a PhD in leadership and human behavior.

“When it’s all hidden behind a military presence — like a Kevlar helmet — people aren’t going to see the face of that officer. Citizens, in effect, depersonalize their police officers for very understandable reasons,” Stamper added.

A fellow former top cop agreed that in the minds of those standing against a line of battle-ready officers, the person behind the badge vanishes.