One of the limitations of research on anger in schizophrenia is that it has tended to look more at the presence of anger rather than how it is stylistically expressed. As has been documented by Chan et al. (2003), persons can respond to equivalent amounts of anger in ways that differ from one another. For instance, the way in which one expresses anger can be considered a trait, which may vary to the extent to which it is expressed inwardly, outwardly, or controllably.