Why does social geography affect our behavior? Why can it lead to group-based bias? Why is it so powerful that it can overcome the forces of the modern world that work to close the spaces between us?

In this chapter, I will answer these questions. It is the centrality of both groups and space in the mind that helps to explain why group-based biases – taking forms as disparate as voter turnout and violent conflict – are affected by social geography. Groups are a central part of the way our minds organize the world. Space is, too. Within our minds, space acts as a demagogue, shaping our mental images of groups.

Not long ago, I boarded a flight from Boston to Washington, DC. Across the aisle was a light-skinned Arab woman in a hijab, the Muslim headscarf, and her Black Muslim husband. Despite all my best intentions as a liberal – one married to a Muslim woman, no less – that simple blue scarf turned my mind to every negative stereotype about the danger of Muslims on planes.

When our own prejudices are laid bare, we realize how easily negative stereotypes can be brought to the surface. This is an awful, awful way to react to somebody. I have in-laws who detest flying because they are aware of the prejudices their fellow travelers have about them.

Near the end of the short flight, I looked over and saw the woman unwrapping her headscarf and thought to myself, “She must not be very religious if she will adjust her scarf in public.” But rather, it turned out, as far as I know, that she wasn't Muslim or Arab at all. She was just a non-Muslim woman with a scarf around her head, tucked in a certain way that made it look like a hijab. This event stuck in my memory because it was remarkable to feel the accessibility of my stereotypes change so quickly, away from those associated with a Muslim woman and toward those associated with a non-Muslim, “American” woman married to a Black man.