Atypical appearance disgust
The items which comprised this factor related to irregular body shape (‘man with a disfigured face’), poverty (touching a ‘homeless man’) and illness (‘hearing someone wheeze heavily’). Differences between the sexes for atypical appearance were small (t2320 = 3.68, P<.001, Difference [D]=0.16). The researchers hypothesized that a stronger female nurture motive might explain these differences.
Items which comprised this factor included problems with the skin and body surface such as ‘… a friend shows you a big, oozing lesion …’ and ‘seeing pus come from a genital sore’. The effect size sex difference was moderate for this type of disgust (t2320 = 7.15, P<0.001, D=0.31).
These items were about prostitution and promiscuity (‘A street prostitute offers you sex for money’, ‘You discover that your romantic partner once paid for sexual intercourse’). Women rated sex significantly more disgusting than men (t2320 = 15.89, P<.001, D=0.70).
These items involved poor hygiene behavior and contamination resulting from poor hygiene (‘Listening to someone sniffle and snort continually’ and ‘Seeing some snotty tissues left on the table’). The difference between the sexes for hygiene disgust was moderate (t2320 = 10.86, P<.001, D=0.48).
This factor comprised of spoiled or unfamiliar foodstuffs that were described as being in decay or deterioration (‘Finding a furry green patch on a loaf of bread’ and ‘eating onion flavored ice-cream’). The difference between the sexes for food disgust was similar to hygiene (t2320 = 10.11, P<.001, D= 0.44).
This factor comprised of all items about animals (raw chicken, slugs, worms, cockroaches, teeming insects). Items included ‘You watch a fly crawl across your friend’s sleeping face’, and ‘After losing a bet, you have to hold a fat wriggling worm in your bare hands for 60 seconds’). The effect size difference between the sexes was the biggest for animal disgust (t2320 = 18.57, P< 0.001, D=0.82).
From an evolutionary standpoint, emotions are seen as directors of action and behaviors; they cause us to take action that puts us in a better state for survival and reproduction. An emerging consensus, the so-called ‘parasite avoidance theory’, posits that disgust in particular has evolved in animals to direct behaviors that reduce the risk of infection.
To test whether the disgust motive reflects how infectious diseases are avoided, researchers (led by the London School of Hygiene & Tropical Medicine [LSHTM]) came up with a list of scenarios – based on disease transmission epidemiology – and surveyed 2679 individuals from the UK, US and Canada to ascertain the level of disgust from each scenario.
‘Transmission route: Fomites (direct contact) — Seeing a chef using an apparently clean dust-pan to serve vegetables in a restaurant.’
Disease threats were categorized into 6 main transmission pathways: 1. direct interpersonal contact; 2. interpersonally through aerosolized droplets; 3. interpersonal sexual contact; 4. contact with a secondary host or vector (e.g. a rodent or insect); 5. ingestion of contaminated food or water; and 6. contact with a fomite.
The researchers hypothesized that the disgust system should have an internal structure that orchestrates different types of protective behavior, and their goal was to clarify that structure.
The results confirmed the ‘parasite avoidance theory’ and shed light on the types of disgust and actions taken. Using Velicer’s MAP analysis, the researchers categorized the disgust structure into 6 factors. These factors ‘likely’ reflect a pathogen detection system that does not ‘see’ microscopic pathogenic microbes directly but has evolved to categories of perceptible cues as to what to avoid.
“We have presented evidence that the disgust motive has a factor structure that reflects the different tasks that human ancestors have had to accomplish to avoid falling prey to infectious disease,” concluded the authors.
Click through the slideshow for a rundown of the 6 factors.
Curtis V, de Barra M. The structure and function of pathogen disgust. The Royal Society. 2018. DOI: 10.1098/rstb.2017.0208.