 21. Emotion and Personality  451
What is clear from this brief review, how -
ever, is that the great majority of studies on 
emotion and personality have focused on the 
PA–NA distinction. In the remainder of this 
chapter, we detail four new developments 
in the science of emotion that are ripe for 
exploration, and point to intriguing ways to 
advance the study of individual differences 
and personality.
The Rise of Social Functionalism: 
Emotions  Structure Social Interactions 
within  Relationships
The first major development we discuss is 
the rise of the social functionalist perspective 
in research on emotion. Most 20th-  century 
research on emotion examined solitary in -
dividuals in the laboratory, with a focus on 
mapping the antecedent causes and subjec -
tive, physiological, and expressive profiles 
of different emotions (e.g., Kreibig, 2010; 
Lench et al., 2011; Matsumoto, Keltner, Shi -
ota, O’Sullivan, & Frank, 2008; Mesquita 
& Frijda, 1992; Roseman, 2013). This work 
was guided to varying degrees by theoreti -
cal claims that emotions serve intrapersonal 
or individual-  level adaptive functions: For 
example, emotion-  related peripheral physi -
ology enables survival and reproduction- 
relevant action (Levenson, 1999); subjective 
experience prioritizes and organizes thought 
in ways that guide social-  cognitive processes 
in ways that are fitting to the present con -
text (e.g., Storbeck & Clore, 2007; Forgas, 
1995).
Since then, the field has witnessed a pro -
nounced shift in focus toward the social 
functions of emotion. This perspective is 
grounded in the general observation of how 
profoundly social humans are accomplish -
ing through relationships the most essential 
tasks, from the raising of vulnerable off -
spring to the gathering of food (Richerson 
& Boyd, 1998; D. Wilson & Gowdy, 2015; 
E. Wilson, 1975). Emerging out of this per -
spective is the idea that emotions structure 
brief social interactions, ultimately enabling 
individuals to meet the problems and oppor -
tunities of social life (e.g., Bartlett, Condon, 
Cruz, Baumann, & DeSteno, 2012; Kelt -
ner & Haidt, 1999; Niedenthal & Brauer, 
2012; Shiota et al., 2006; van Kleef, 2016). This shift has deep theoretical origins. It has 
precedent in analyses of emotions as mediat -
ing the relationship between the developing 
child and its caregivers (J. Campos, Cam -
pos, & Barrett, 1989). A social functional 
approach to the emotions can also be found 
in European ethology, which conceptualized 
emotions as the grammar of social living— 
the set of mechanisms by which individuals 
interact (Eibl-  Eibesfeldt,1989).
A social functionalist approach to the emo -
tions translates to two core assumptions that 
have guided a next wave of science. The first 
is that emotions provide moment-  to- moment 
structure to the social interactions we expe -
rience throughout the day (van Kleef, 2016). 
For example, early parent–  child interactions 
are structured by closely synchronized emo -
tional displays such as cries, touch, mutual 
gaze, and laughter, and the appraisals and 
inferences these expressive behaviors evoke 
(Feldman, 2007). The flirtations that initi -
ate romantic commitments include subtle 
exchanges of coy glances, blushes, postural 
shifts, suggestive smiles, and provocative 
touches (Moore, 2010). Interactions within 
social hierarchies include emotion-  laden be -
haviors that reduce the rank of some (e.g., 
teasing, derogation, gossip, laughter, threat 
displays, and sarcasm), and actions that 
elevate the rank of others (e.g., praise, ad -
miration, and imitation) (Feinberg, Willer, 
& Keltner, 2012; Keltner, Young, Oemig, 
Heerey, & Monarch, 1998; Van de Ven, 
2017). Hostilities toward outgroups are 
riddled with the rhetoric of disgust and con -
tempt (Mackie, Silver, & Smith, 2004; Rose -
man, 2013).
The second assumption is that, building 
on these momentary interactions, emotions 
are at the heart of the long-term interde -
pendent bonds that are a defining feature 
of the human species, a foundation for in -
dividual development, and a central as -
pect of contemporary life (e.g., Bartlett et 
al., 2012; Bowlby, 1969; Keltner & Haidt, 
2003; Nesse, 1990; Shiota et al., 2006). At -
tachment processes are rooted in emotions. 
So too are friendships. Our place in lasting 
hierarchies is negotiated through the emo -
tions we express, feel, and perceive in others. 
Family life is rife with emotion. It is hard to 
imagine these relationships absent recurring 
and strong emotion.