If you join a teacher fraternity and choose to dress like most of the others…

Social influence on behaviour is commonly classified into three forms based on why the behaviour changes: conformity is a voluntary shift in one's own actions or appearance to match a group's typical norms, made with no explicit request or command from anyone; compliance is a change made in direct response to a specific request from another person or group; and obedience is a change made in direct response to an order from a recognised authority figure. Group identity, by contrast, is simply the psychological sense of belonging to a group, not a behaviour at all.

In the scenario, a new member of a teacher fraternity begins dressing the way most of the group already dresses. Nobody asks them to do so and nobody orders them to do so; the change is entirely self-initiated, driven only by a wish to match the group's existing norm. That is the defining feature of conformity: an unprompted, voluntary alignment with group norms.

Checking each option against this definition:

• Group identity — names the sense of belonging to the fraternity, not the act of changing one's dress to match it; it does not describe any behaviour change.

• Group obedience — would require a specific order from an authority figure, for example a supervisor mandating a dress code; no such order appears in the scenario.

• Group compliance — would require a specific request from a person or the group asking the individual to dress a certain way; the scenario contains no such request.

• Group conformity — matches directly: the dress change happens purely because the individual wants to align with what most others in the group already wear, with no request or order involved.

Since the behaviour is a voluntary, unprompted alignment with the group's existing norm rather than a response to any request or order, it is best classified as group conformity.