If a stranger or acquaintance comes closer than this range, they are perceived as invading one's personal space. This varies according to culture. North Americans have a larger personal zone than South Americans, for instance. Eye contact mediates the effect of personal space. When personal zones are violated, as in elevators, avoiding eye contact reduces the stress of the encounter.
Eye contact has far broader effects.
We look into each other's eyes for signals of what is going on inside. In our culture, eye contact signifies trust, confidence, and believability. But eye contact is meaningful in every culture. In other cultures, the absence of direct contact signifies deference to those more powerful. In fact, power and dominance dynamics in groups can often only be handled with nonverbal methods .