The president and the first lady added their voices this week to the raging conversation on race following the protests that erupted in the wake of grand juries not indicting police officers who killed two unarmed black men — Michael Brown and Eric Garner.

In an interview with People magazine, Mrs. Obama recalled a trip to Target during which “the only person who came up to me in the store was a woman who asked me to help her take something off a shelf. Because she didn’t see me as the first lady, she saw me as someone who could help her. Those kinds of things happen in life. So it isn’t anything new.”

Could the Target shopper who asked Mrs. Obama for help simply not have recognized her and needed, presumably, a taller person’s assistance? Sure, in theory. Or could the encounter have been disdainful and presumptuous, a manifestation of some inherent bias? Sure, that too could have been the case.

Could there have been some combination of those forces at play? Also possible.

The truth is, we don’t know. The lady asking for help might not even know. We are not always aware of our biases, let alone are we always able to articulate them. And people can sometimes be hypersensitive to bias when they are submerged in it.