According to a Gestalt principe called ...., when looking at a crowd of people , one tends to perceive people grouped close together as belonging to a common or related group.

The Gestalt principle that refers to this phenomenon is known as "proximity."

The Gestalt principle you are referring to is called "proximity." According to the principle of proximity, when we look at a crowd of people, we tend to perceive individuals who are grouped close together as belonging to a common or related group. This principle suggests that our brains automatically organize visual elements that are near each other into groups, allowing us to perceive the relationships among those elements. By perceiving these groups, we can make sense of complex visual scenes more easily.