How to check the photo of an unnamed person?

In the "add people" feature, I would like to be able to view the photo of a recognized but unnamed person. Sometime you need context to identify the person. Then I would add him or her to my list of people. And there I would assign a name. But I do not know how to preview the full photo without adding the person to my people list. I did not find a way to do it in El Capitan, and I don't know how to do it in Sierra. How can I do it?

I want to avoid adding faces/persons to my list of people if I cannot or do not want to name them. After I have added a person, there seems to be no way to remove him or her from the list of people. You can only "hide", which is not the same.