Palmer and Hollin (1998) used questionnaires to compare the moral reasoning abilities of 126 male convicted offenders with 122 male non-offenders. The researchers found that male offenders had significantly poorer moral reasoning compared to male non-offenders, supporting moral reasoning as an explanation of criminal behaviour
Thornton and Reid (1982) found criminals convicted of robbery were more likely to be at the pre-conventional morality stage than criminals convicted of assault. This suggests moral reasoning is a better explanation of some criminal behaviours than others.
There are examples of criminals of all stages of moral reasoning, which suggests that other factors besides pre-conventional moral reasoning are needed for a complete explanation of criminal behaviour.