Abstract:

Disgust emotion has been evolved to avoid disease infection. When the risk of disease is high, people will be more likely to comply with the commonly accepted social rules and practices to reduce the chance of infection. It has been demonstrated that, when primed with disgust emotion, compared with the neutral emotion, people rated moral transgressions and violations more harshly. However, disgusting emotion was not bring inborn. The disgust emotion responds to parasite pressure not only over evolutionary time, but also over lifetimes. Rozin et al. (2000) proposed a developmental model of disgust describing the particular categories of disgust elicitor appear in a certain sequence and Stevenson’s study (2010) demonstrated this model, that is core disgust developed first, while sociomoral disgust was the last. Therefore, the relationship between disgust and sociomoral judgment was developed with growth. However, there have not been studies to examine the development of the disease avoidance function of disgust emotion. In this study, we employed grade 1 (about 7 years old) and grade 4 (about 10 years old) primary school students and adults (about 21 years old) to investigate the influence of disgust on moral judgment across age. Half of the participants first rated a set of disgusting stimuli pictures of feces, dead insects, and rotten foods and then completed the moral judgment, whereas the other half of participants first completed the moral judgment and then rated the disgusting stimuli. Moral judgment behaviors included some moral violation behaviors (e.g., tearing a friend’s favorite book apart, giving a piece of moldy bread to a homeless person, cutting up the neighbor’s dog that died in an accident and eating it for dinner). Participants rated the disgusting stimuli on a 5-point scale, with the following anchors: really dislike, dislike a bit, unsure, like a bit, and really like. On a 3-point scale ranging from 1 (not at all) to 3 (very much), participants rated the extent to which each of the three types of behavior was wrong, the extent to which it deserved punishment, and the extent to which they wanted to make a friend (for primary school student participants) or to be a roommate (for adult participants) with the person committing the moral transgression. The results showed that both adults and grade 4 students under the disgust condition rated the conduct related moral violations behaviors more harshly than the control group under the control condition. Grade 4 students under the disgusting condition avoided the person committing the moral violation more than participants under the control condition. However, the same results were not found in primary school students of lower grade. The correlation between the disgust ratings and the critical judgment of moral transgression was statistically significant in the primary school student participants. It is concluded that that the influence of disgust emotion on moral judgment appears after 7 years of age and develops with growth, then stays at a constant level in adulthood.