Morality and soap in engineers and social scientists: the Macbeth effect interacts with professions.

Several studies demonstrate that physical cleansing is actually efficacious to cope with threatened morality, thus demonstrating that physical and moral purity are psychologically interwoven. This so-called Macbeth effect has been explained, for example, by the conceptual metaphor theory that suggests an embodiment of the moral purity metaphor. Recent research draws attention to individual differences when using conceptual metaphors. The present study shows that the moral purity link interacts with different professions. Engineering and social science students were asked to hand copy a text in which the protagonist behaved in an immoral way (or in a moral way, control condition). Subsequently, they had to rate cleansing and other products. Both groups of participants showed higher ratings for cleansing products when hand copying the unethical story, but this Macbeth effect was significantly stronger for the group of engineering students. The results demonstrate that the Macbeth effect interacts with individual differences of the chosen profession. The outcome is discussed in terms of recent theories on individual differences in disgust sensitivity.