A couple of Sundays ago, I went with some friends to a popular local eatery for breakfast. Bustling at any time of the week, the place is so busy on weekends that upon arriving, diners find themselves at the back of a long line that not uncommonly stretches halfway around the block. Once finally inside the front door, one still finds oneself separated from the counter by a line of 15 to 20 people, and increasingly aware of the limited number of available tables as one approaches the cashier taking orders.

In spite of the anxiety one feels during this slow crawl to the counter, a table virtually always comes available just in time, due in large part to the establishment’s strict policy of requiring diners to display order numbers on their tables before taking a seat. On this particular occasion, however, a pair of diners decided they would bypass the policy. A woman slipped out of line and took a table against the wall while her partner, standing right in front of us, pretended not to know her.

When my friends and I ordered and found our own table—which, as usual, proved to be no problem in spite of the policy violation—we grumbled over the incident throughout the meal to the extent that I’m not sure if any of us remember what we actually ate.

Looking back on the incident, I am surprised by the vehemence of the anger it triggered in us. Even more surprising, however, was how very personal our anger was. We didn’t view the policy infringement as a case of ordinary people taking advantage of an opportunity to bend the rules when they thought no one was looking. We saw it as a sign of bad character—the actions of people temperamentally inclined to view themselves as being above the rules by which the rest of polite society operates. A study recently published in PLOS One sheds some light on the reasons for our unreasonably personal reaction. It turns out that some classes of bad behavior are more likely to touch a nerve than others.

Domains of human morality

Building on previous research viewing morality as comprising several different domains, researchers from the University of Michigan and the University of Illinois investigated the “weight given to various moral acts and how social judgments may differ as a function of social domain.” In other words, they wanted to find out whether or not all categories of “moral” behavior are created equal.

Dividing the moral landscape into seven different domains—family, reciprocity, bravery, hierarchy, equality, property, and unity & communal sharing—the research team presented a group of participants with seven positive and seven negative behaviors for each domain, attributing each behavior to a different “social target” (i.e., hypothetical person). In the family domain, for example, participants were presented with the behavior statements, “Mark helped a member of his family” and “Dave failed to help a member of his family,” and in the hierarchy domain, they were presented with the statements, “Phil honored the rules of his superiors” and “Jake failed to honor the rules of his superiors.”

Morality domains and social judgment

Presented with these moral actions, participants were asked to give their responses to the social target on three points: (1) whether or not the person was “principled, ethical, and morally upstanding,” (2) whether the described behavior was due to something about the person’s character or the result of the situation the person was in, and (3) whether or not they would be willing to cooperate with the social target.

In participants’ responses to all three questions, the domains of equality and property—how fairly people treat us and how much respect they show for our personal belongings—elicited by far the strongest reactions. Behaviors adhering to the principles of equality and property were viewed more positively than adherence in the five other domains, and violations in these two domains were viewed more negatively than violations in the other domains.

Equality and property violations draw the harshest social judgment

Participants were also more likely to view behaviors within these two domains—whether positive or negative—as being the result of the target’s personal disposition rather than a product of situational circumstances or environment. And when asked whether they would be “willing to cooperate” with the target (letting them borrow one’s car, for example, or telling them personal information), participants showed far less inclination to trust targets who committed violations in the equality and property domains.

The study indicates that, of all the different domains that make up the moral landscape of our daily lives, it is people’s behavior in the equality and property domains that evokes the most intense and personal reactions from us. We feel appreciation and gratitude when they treat us fairly and show respect for our belongings, and feel an equivalent degree of outrage and anger when they fail to do so.

In light of the results of these studies, my group’s reaction to the table-snatching couple was not all that surprising. Their overt disregard for a house rule that everyone else in the restaurant followed was a violation of the equality domain, and their consequent appropriation of coveted seating that, by all rights, belonged to whoever stood between them and the counter, violated the property domain. And like the participants in the studies described above, we took these violations personally, blaming the sinners rather than the sin.