What exactly does it mean to be nice? Is it about being fair and respectful, or is it more about helping people in need? Both? In personality psychology, the quality of being nice falls under a broad category called agreeableness. This trait – one of five dimensions on the Big 5 model of personality – refers to how well an individual gets along with others. Compassion refers to our tendency to be emotionally concerned about others. Politeness is defined as our tendency to demonstrate good manners, adhere to social norms and avoid aggression. A growing body of research shows that personality traits can, at least in part, be changed through intervention.