Humans are often creatures of habit. People tend to regularly take the same route to work, choose the same restaurants to eat in and create routines for their daily tasks. Along these same lines, people also have a tendency to sit in the same spot in a room. Quite often, the seat in which a person sits the first time they enter a room is the one to which they continue to gravitate.
As fascinating as this might be to behavioral science, it is actually embedded within Jewish tradition.
“Rabbi Helbo, in the name of Rabbi Huna, says: Whosoever has a fixed place for his prayer has the God of Abraham as his helper. And when he dies, people will say of him: Where is the pious man, where is the humble man, one of the disciples of our father Abraham! -- How do we know that our father Abraham had a fixed place [for his prayer]? For it is written [in Genesis 19:27]: And Abraham got up early in the morning to the place where he had stood” (Talmud Brachot 6b).
A person’s set place in a synagogue is known in Hebrew as a makom kavua.* It is considered proper to always sit in one’s makom kavua when at prayer. However, if another person, such as a visitor, unsuspectingly sits in one’s place, it is better to sit near one’s makom rather than embarrass the other person. One’s makom kavua, while important, is not set in stone, and one may change it if one is unhappy with the space.
For families that attend services together, the same rules of respect that apply to parents’ regular places at the table apply to their seats at the synagogue. Additionally, there is a custom to change one’s synagogue seat when one is in mourning.
*A makom kavua is not limited to a specific chair but the area in which one sits and is generally thought to be a span of daled amot, a radius of 6-8 feet.