Opinion It doesn’t smell right

The emotion of disgust,many researchers believe,evolved to protect us from contamination. It is easily elicited by faeces,pus,vomit,putrid meat and other substances linked to pathogens. A single picture,a few choice words and,yes,a slight odour can elicit a surprisingly intense reaction.

Disgust’s origins as a protector against contamination can be seen in its characteristic and universal facial expression: the wrinkling of the nose,curling of the upper lips and protrusion of the tongue. Wrinkling the nose has been shown to prevent pathogens from entering through the nasal cavity,and sticking out the tongue aids the expulsion of tainted food and is a common precursor to vomiting.

But disgust does more than just keep us away from poisonous substances. It also exerts a powerful and idiosyncratic influence on judgment. People who are feeling disgust

become harsher in their judgments of moral offences and offenders.

Consider recent experiments by the psychologist Simone Schnall and her colleagues: people who were sitting in a foul-smelling room or at a desk cluttered with dirty food containers judged acts like lying on a résumé or keeping a wallet found on the street as more immoral than individuals who were asked to make the same judgments in a clean environment. This general finding has been replicated by other psychologists using a variety of disgust elicitors and moral behaviours.

In another experiment one of us (Dr Pizarro) was involved in,a foul ambient smell — emitted,unbeknownst to test subjects,by a novelty spray — caused people answering a questionnaire to report more negative attitudes toward gay men than did people who responded in the absence of the stench. Apparently,the slightest signal that germs might be present is enough to shift political attitudes towards the right.

Why does a mechanism that originally evolved to protect us from pathogens affect our reactions to people and behaviour? One possibility is that early humans were endangered by contact with outside clans that carried diseases for which they had not developed immunity. Reacting with disgust towards members of groups seen as foreign,strange or norm-violating might have functioned as a behavioural immune system.

Moreover,similar effects were demonstrated when

researchers increased individuals’ perceived vulnerability to disease (for example,by showing them pictures of a woman battling cartoon germs in a kitchen). Participants shown such pictures felt more negatively about,say,Nigerian

immigrants than did participants who were shown slides of non-pathogenic dangers,like school bus accidents or electrical appliances teetering above bathtubs.

While this avoidance mechanism may have conferred a survival benefit on our ancestors,it can easily overfire,

causing us to shun groups and people inappropriately and

unfairly. And because it remains tightly linked to the disgust we experience in the presence of oral contaminants (like putrid meat),it makes sense that inducing disgust with a rotten smell could cause a shift in attitudes towards certain individuals or social groups.

Mr Paladino,a Tea Party activist,seems no exception to this general pattern. Obviously,the malodorous mailer alone can’t explain how Carl Paladino steamrolled Rick Lazio in the primary,62 per cent to 38 per cent. Nonetheless,election officials should keep the psychology of disgust in mind — and be wary of Purell dispensers or awful odours mysteriously appearing at polling places this November 2.

Liberman is a professor of political science at Queens College and the Graduate Centre of the City University of New York. Pizarro is a professor of psychology at Cornell.