BEHAVIORAL IMMUNE SYSTEM Week 14 Physiological Immune System

BEHAVIORAL IMMUNE SYSTEM Week 14

Physiological Immune System Mounting an immune response is metabolically very costly.

Prevention is better than cure Pre-emptive action: Avoid infection is less costly than combating infection

Behavioral Immune System 1. 0 • A suite of psychological mechanisms designed to avoid infection. • Note: This is not a branch of behavioral medicine, i. e. , not how behaviors immune system

How does it work (1)? By inducing disgust Curtis et al. (2004). Evidence that disgust evolved to protect risk of disease. Proc R Soc Lond.

Disgust Qualia Revulsion feeling Physiology Nausea Wrinkled nose (sometimes laughter)* Cognition Fear of oral incorporation Fear of contamination, even irrationally Fear of animal-nature reminders *Hemenover & Schimmack (2007). Mixed feelings of amusement and disgust. Cog & Emo.

Classic studies • Excrete a cup of saliva. Swallow it. • Eat chocolate cake shaped like poop. • Eat a sterilized cockroach. Rozin et. al. (1986). Operation of the laws of sympathetic magic in disgust and other domains. J Pers Soc Psychol.

Newer studies Even nutritious food is seen as disgusting, if they are foreign Chan et al. (under review). Disgust and fear lower olfactory threshold. [Data from pretest].

How does it work (2)? By the “smoke detector principle”: Cognitive biases Similar to allergies – Erring on the conservative side: False alarms are better than misses Miller & Maner (2012). Overperceiving disease cues: The basic cognition of the behavioral immune system. J Pers Soc Psychol.

How does it work (2)?

How does it work (3 A)? By orientating attention automatically

How does it work (3 B)? By sustaining attention Ackerman et al. (2009). A pox on the mind. J Exp Soc Psychol. Cisler et al. (2009). Attentional bias differences between fear and disgust. Cog & Emo. Van Hoof et al. (2013). Disgust- and not fear-evoking images hold our attention. Acta Psychologica.

How does it work (4)? By lowering threshold of detection

Visual detection Successful behavioral avoidance depends on first detecting the threat Sherman et al. (2012). The faintest speck of dirt: Disgust enhances impurity detection. Psychol. Sci.

Olfactory detection Some threats are better detected by smelling than by looking. So, will disgust individuals have better smelling capabilities for disease cues?

Smelling disease cues Humans are able to smell cues of diseases in other humans Olsson et al. (2014). The scent of disease: Human body odor contains an early chemosensory cue of sickness. Psychol. Sci.

Olfactory thresholds are lowest when… Navarrete-Palacios et al. (2003). Lower olfactory threshold during the ovulatory phase of the menstrual cycle. Biol Psychol.

Olfactory detection Will disgusted individuals have better smelling capabilities? You know this already from Week 8. Chan et al. (under review). Disgust and fear lower olfactory threshold.

How does it work (5)? Through personality: The disgust sensitivity questionnaire Core It bothers me to hear someone clear a throat full of mucus. Contamination I never let any part of my body touch the toilet seat in a public washroom. Core disgust Contamination Animal nature It would bother me to be in a science class, and see a human hand preserved in a jar. Animal nature Haidt et al. (1994). Individual differences in sensitivity to disgust: A scale sampling seven domains of disgust elicitors. Pers Ind Diff. Olatunji et al. (2007). The disgust scale: Item analysis, factor structure, and suggestions for refinement. Psychol Assess.

How does it work (5)? Through personality: The disgust sensitivity questionnaire ^Would you… Actual (n = 68) r. DS Flap like chicken 37 -, 08 Eat cornchip 58 -, 22 Poop-shaped fudge 38 -, 31* Pin in pig’s head 14 -, 31* Used someone’s hat 47 -, 33* Eat ashes 1 -, 33* Lip sterilzed cockroach 7 -, 43* Haidt et al. (1994). Individual differences in sensitivity to disgust: A scale sampling seven domains of disgust elicitors. Pers Ind Diff. Olatunji et al. (2007). The disgust scale: Item analysis, factor structure, and suggestions for refinement. Psychol Assess. ^Rozin et al. (1999). Individual differences in disgust sensitivity: Evaluations of behavioral measures. J Res Pers.

How does it work (5)? People high in “germ aversion” are low in extraversion. Duncan et al. (2009). Perceived vulnerability to disease. Pers Ind Diff.

How does it work (6)? By enhancing memory to disgust cues

How does it work (6)? Encoding Retrieval Chapman et al. (2009). Evidence for the differential salience of disgust and fear in episodic memory. J Exp Psy.

How does it work (7 A)? By integrating with the physiological immune system BIS PIS Seeing a sick person more immuno T-cells Schaller et al. (2010). Mere visual perception of other people’s disease symptoms facilitates a more aggressive immune response. Psy Sci.

How does it work (7 B)? By integrating with the physiological immune system PIS BIS Suppression of physiological immune system (e. g. , during mothers’ 1 st trimester) more ethnocentric & xenophobic attitudes. Navarrete et al. (2007). Elevated ethnocentrism in the first trimester of pregnancy. Evol Human Beh.

Other cool findings Age & Disgust sensitivity Curtis et al. (2004). Evidence that disgust evolved to protect risk of disease. Proc R Soc Lond.

Other cool findings Cross cultural disgust sensitivity 3, 0 3, 6 2, 5 3, 4 India 2, 0 3, 2 1, 5 3, 0 1, 0 2, 8 Ghana USA male female Skolnick & Dzokoto (2013). Disgust and contamination: A cross-national comparison of Ghana and the United States. Front Psy. Chan & Ginting (in progress). Gender differences in disgust sensitivity is not universal.

Behavioral Immune System 2. 0 • These mechanisms have implications for the regulation of various social behavior, sometimes in nonobvious ways. • The kinds of social behavior affected should be traceable to components of disgust, even though it may be irrational.

Recall: The components of disgust Oral incorporation Contamination Animal nature

Why Animal Aversion? Rot easily Produce feces Embody emotionally charged ideas Closer to humans; evokes cannibalism taboo Need to maintain boundary between selves and animals: mortality fears Loughnan et al. (2014). The psychology of eating animals. Cur Dir Psychol Sci.

The meat paradox The eaters The eaten The act of eating Google “Kittiwat Unarrom human bread”

Culinary systems Not just the type of food we eat… But our whole culinary thinking starting from food preparation! Haidt (2008). Disgust. In Handbook of Emotions Martins & Pilner (2006). Identification of the characteristics of foods underlying rejections based on disgust. Appetite. Bastian, Loughnan, Haslam, & Radke. (2011). The denial of mind to animals used for human consumption. Per Soc Psy Bull.

Political preferences N = 25000 Americans Inbar et al. (2012). Disgust sensitivity, political conservatism, and voting. Soc Psychol Per Sci. Inbar et al. (2009). Conservatives are more easily disgusted than liberals. Cog & Emo. Tybur et al. (2010). Extending the behavioral immune system to political psychology. Evol Psychol

Outgroups WWII: Jews were described as “vermin”, “bad as the plague”, “pestilence”, “parasites”. Disease-related derogatory descriptives Disgust Action to remove disgust agents Taylor (2007). Disgust is a factor in extreme prejudice. Br J Soc Psy.

Evidence “How much funds should our Canadian government spend to recruit workers from Poland (familiar) or Peru (foreign)? ” Faulkner et al. (2004). Evolved disease-avoidance mechanisms and contemporary xenophobic attitudes. Grp Proc Intergrp Beh.

At a more subtle level: Prejudice People with physical disfigurements Obese Elderly Anyone who looks…“different”…in a negative way Ackerman (2009). Disjunction of attention and memory in the processing of physical disfigurement. J Exp Soc Psy.

Applications to behavioral change? Moralization of behavior* “This is immoral” Because moralization triggers disgust, which can sometimes defy rationalizations Haidt & Singh (1999). The moralization of cigarette smoking in America. J Consumer Psychol. *Chan et al. (2014). Reminders of God lead to greater risk taking. Soc Psy Pers Sci.

But what about moral disgust? Behavioral immune system Psychological immune system (immunizing from psychological contamination) • Neurobiological similarities between moral disgust and core disgust 1 • Produce metaphor-consistent effects 2 1 Borg et al. (2008). Infection, incest, and iniquity: Investigating the neural correlates of disgust and morality. J Cog Neurosci. 2 Lee & Schwarz (2010). Dirty hands and dirty mouths. Psychol Sci.

The broader picture Psychological immune system Human threat management system 1 • Quick to detect angry faces, esp. male + outgroup faces 2 • Negativity bias 3 Behavioral immune system 1 Neuberg • Better sound detection in avoidant state 4 et al. (2011). Human threat management systems: Self-protection and disease avoidance. Neurosci Biobehav Rev. 2 Becker et al. (2007). The confounded nature of angry men and happy women. J Pers Soc Psychol. 3 Baumeister & Bratslavsky (2001). Bad is stronger than good. Rev Gen Psychol. 4 Chan et al. (in prep). Vigilance in hearing: Avoidance lowers auditory threshold.