Psychological Science Demo - 1218

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random slopes for the effect of interpersonal value
across stimuli. We removed random slopes that prevented model convergence. People were more comfortable with exposure to pathogens when the targets were
described as high in prosocial personality traits (M =
−0.93, 95% CI = [−1.04, −0.81]) than when they were
described as low in prosocial personality traits (M =
−1.8, 95% CI = [−1.89, −1.70], F(1, 822) = 126.1, p < .001.
When WTR was added as a predictor, both WTR and
the manipulation were related to comfort with exposure
to pathogens (both ps < .001; see Fig. 2). The effect of
the manipulation and WTR remained when we further
controlled for participant pathogen-disgust sensitivity,
participant sex, and target sex, ps < .001. Full details
are provided in the Supplemental Material.

Discussion
Results from each of three studies revealed that motivations to avoid infection-risky contact varied markedly
across targets with no clear symptoms of illness. Much
of this variation was accounted for by targets' interpersonal value to perceivers. Participants were less averse
to infection-risky contact with targets from categories
that are, on average, more highly valued (e.g., close
friends vs. disliked others), and they were less averse
to infection-risky contact with agreeable and honest
strangers than with disagreeable and dishonest ones.
Further, even within target categories, comfort with
infection-risky contact related to a continuous measure
of interpersonal value-for example, people who valued
their closest friend more were also less averse to infection-risky contact with that friend. We discuss how these
findings can inform both the burgeoning behavioralimmune-system literature and our understanding of
how infectious disease spreads.

Implications for understanding the
behavioral immune system
The behavioral-immune-system literature largely focuses
on understanding how people detect and respond to
features that putatively provide information regarding
infectiousness, such as pustules and swellings (Ackerman
et al., 2018; Murray & Schaller, 2016; Neuberg et al.,
2011; Oaten et al., 2011). The current study is a step
forward in understanding pathogen avoidance even in
the absence of such cues, and it raises critical issues
for future research.
First, growing evidence suggests that the behavioral
immune system does not output the same pathogenavoidance motivations across all contexts. It is instead
flexible, weighing strands of information to determine
the fitness value of contacting another person or item

Tybur et al.
(Neuberg et al., 2011; Tybur & Lieberman, 2016). The
current findings demonstrate that interpersonal value
is one such strand. Other findings suggest that pathogen avoidance is relaxed in situations that require some
exposure to pathogens, such as sexual interactions
(e.g., Fleischman et al., 2015) and childrearing (e.g.,
Case et al., 2006). Future work can test whether relaxed
pathogen avoidance toward offspring and mates results
only from their high interpersonal value or whether
sexual value and genetic relatedness, which inform
interpersonal value (but are not redundant with it),
additionally shape pathogen avoidance (cf. Tooby et al.,
2008).
Second, researchers have speculated that people are
more disgusted by infection-risky contact with strangers
relative to friends because social familiarity is treated
as a cue to infectiousness, just as rashes and sores are
(Curtis et al., 2004; Peng et al., 2013; Stevenson & Repacholi,
2005). Similarly, the behavioral-immune-system literature is replete with proposals that prejudices toward
members of various groups partially stem from people
treating morphological features (e.g., in the cases of the
physically disabled, obese, and elderly) or foreign ecological origin (e.g., in the case of immigrants) as cues
to infectiousness (for a summary, see Murray & Schaller,
2016). The current results suggest an alternative-or, at
least, supplementary-approach to understanding how
the behavioral immune system contributes to social
biases: Prejudices toward the aforementioned groups
might result from perceptions of interpersonal value
rather than perceptions of infectiousness. Recent studies has reevaluated claims that anti-immigrant prejudices partially result from perceptions that foreign
ecological origin is indicative of infectiousness (e.g.,
Karinen, Molho, Kupfer, & Tybur, 2019; van Leeuwen
& Petersen, 2018); future work could similarly clarify
whether the behavioral immune system outputs prejudices toward the obese, elderly, and physical disabled
because they are perceived as infectious or because
they are perceived as not offering the interpersonal
benefits that offset the infection risks posed by any
social interaction.
Third, if infection-risky contact is embraced with
interpersonally valued others and avoided with interpersonally devalued ones, then contact rituals (e.g.,
hugs, handshakes) might be used to signal, regulate,
and maintain interpersonal valuation. Refusals to
engage in such rituals with a specific target might be
interpreted as suggesting that the target is not valued
enough to risk infection, is perceived as having some
symptom of contagious illness, or both. These considerations might contribute to our understanding of the cultural evolution and maintenance of greeting rituals. They
also highlight an important limit on the generalizability

Psychological Science Demo

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