1. Everything is Connected
An extended example…
The behavioral immune system revisited.
- Visual attention.
- Cultural differences.
- Clinical disorders.
- Psychoneuroimmunology.

2. The behavioral immune system revisited…

3. Implications for visual attention.

4. [Longer response time indicates that face holds attention for longer.]
(Ackerman et al., 2009)

5. [Longer response time indicates that face holds attention for longer.]
Key results:
Compared to “normal” faces, disfigured faces hold attention for longer.
Especially under conditions in which perceivers feel more vulnerable to infection.
(Ackerman et al., 2009)

6. Implications for cultural differences.

7. Cross-national differences in extraversion:
(Schaller & Murray, 2008)

8. Cross-national differences in the magnitude of conformity effects in psychology experiments.
(Murray, Trudeau, & Schaller, 2011)

9. Cross-national differences in percent of left-handed people:
(Murray, Trudeau, & Schaller, 2011)

10. Higher levels of pathogen prevalence associated with fewer…
Innovation:
Higher levels of pathogen prevalence associated with fewer…
Nobel prizes in the sciences.
Patents.
Other indicators of technological innovation.
(Even when controlling for cross-national differences in economic development, etc.)
(Murray, 2014)

11. Cross-national differences in authoritarian attitudes:
(Even when controlling for cross-national differences in economic development, etc.)
(Murray, Schaller, & Suedfeld, 2013)

12. Systems of government:
Cross-national analyses of contemporary political systems:
Higher pathogen prevalence associated with lower levels of democracy.
(Thornhill, Fincher, & Aran, 2009)
Cross-cultural analyses of small-scale societies:
Higher pathogen prevalence associated with authoritarian governance.
(Murray et al., 2013)

13. Cross-national differences in individualism / collectivism:
(Even when controlling for cross-national differences in economic development, etc.)
(Fincher, Thornhill, Murray, & Schaller, 2008)

14. Implications for clinical disorders.

15. Obsessive-Compulsive Disorder (OCD): (quoted from CPA fact sheet)
- “Some individuals suffer with a special type of unwanted thought intrusion called obsessions... The most common obsessive content involve (a) contamination by dirt or germs, (b) losing control and harming oneself or other people, (c) doubts about one's verbal or behavioural responses, (d) repugnant thoughts of sex or blasphemy, (e) deviations from orderliness or symmetry, (f) the possibility of sudden sickness (e.g., fear of vomiting), or (g) the need to save even the most useless objects.”
- “Compulsions are repetitive, somewhat stereotypic behaviours or mental acts that the person performs in order to prevent or reduce the distress or negative consequences represented by the obsession... Typical compulsions include repetitive and prolonged washing in response to fears of contamination, repeated checking to ensure a correct response, counting to a certain number or repeating a certain phrase in order to cancel out the disturbing effects of the obsession.”

16. Obsessive-Compulsive Disorder (OCD):
Results from lots of studies…
People who are more easily disgusted are more likely to display typical symptoms of OCD (e.g., fear of contamination, compulsive washing).
Implies that OCD may result from hyperactive “behavioral immune system.”

17. Some possible fitness-relevant benefits of these behavioral symptoms:
Depression:
Background:
Symptoms of depression: depressed mood; fatigue, decreased activity, social withdrawal, etc.
“Sickness behavior”: depressed mood; fatigue, decreased activity, social withdrawal, etc.
Some possible fitness-relevant benefits of these behavioral symptoms:
Conserve metabolic resources that can be used to fight existing infections.
Reduce risk of contracting new infections.
Reduce risk of transmitting infections to kin.
The “infection-defense hypothesis” of depression: Depression may reflect physiological mechanisms that evolved as defenses against infection.

18. Psychoneuroimmunology.

19. One intriguing hypothesis:
Visual perception of potentially infectious things in the immediate environment

20. Visual perception of things that arouse disgust
Results from several recent experiments:
Visual perception of things that arouse disgust

21. (Aggressiveness of immune response)
White blood cells’ production of interleukin-6 (IL-6) following bacterial stimulation.
(Aggressiveness of immune response) ?
[Or]
(Schaller, Miller, Gervais, Yager, & Chen, 2010) 21

22. Increase in production of IL-6
Results:
Increase in production of IL-6
More aggressive
immune response
to infection
Guns Photos
Disease Photos
(Schaller, Miller, Gervais, Yager, & Chen, 2010)