 31. Persons, Situations, and Person–Situation Interactions  669
(e.g., Belsky & Pluess, 2013; Caspi, Hariri, 
Holmes, Uher, & Moffitt, 2010). A second 
direction looks forward in time to identify 
(and perhaps predict) life outcomes that 
eventually become associated with person -
ality dispositions. Researchers have found 
that a number of important outcomes can 
be predicted from measures of personality 
gathered years earlier, including criminal 
behavior, mental health, occupational suc -
cess, relationship satisfaction, and physical 
well-being (e.g., Ozer & Benet-Martínez, 
2006; Soto, 2019).
Dispositionally oriented research has re -
vealed many important facts, two of which 
are particularly relevant here. First, many 
personality dispositions can be distilled to 
a small set of fundamental traits. The Big 
Five framework identifies extraversion, neu -
roticism (or its converse, emotional stabil -
ity), agreeableness, conscientiousness, and 
openness to experience (John, Chapter 2, 
this volume). The HEXACO framework 
(Honesty–  Humility, Emotionality, eXtra -
version, Agreeableness, Conscientiousness, 
Openness to Experience) is similar, but 
adds Honesty–  Humility as a sixth factor 
(Ashton & Lee, 2007). Any comprehensive 
theory of personality must account for such 
dispositional organization. A second fact is 
that broad personality characteristics, such 
as personality traits, matter. They predict 
behavioral trends and have consequential 
outcomes, again ranging from criminal be -
havior to success in occupations and rela -
tionships to—  literally—  the length of one’s 
life (Ozer & Benet-Martínez, 2006; Roberts, 
Kuncel, Shiner, Caspi, & Goldberg, 2007; 
Soto, 2019). For many outcomes, broad per -
sonality dispositions matter as much as, or 
more than almost anything else, including 
socioeconomic status, money, or relation -
ship quality. Any comprehensive theory of 
personality must find room for such disposi -
tions.
The Situational  Roots
The situational root of interactionism is the 
recognition that a person’s behavior is af -
fected by attributes of the situation in which 
the behavior occurs. People are particularly 
likely to enact a given behavior in particu -
lar situations, and there is something about 
those particular situations  that triggers or elicits that behavior. For example, a situa -
tion that includes one’s friends likely elicits 
talkativeness and affection. A situation that 
includes loud music and adult beverages may 
elicit dancing.
Situationally oriented research often fo -
cuses on behavioral differences across situ -
ations. Prototypically, the situations are ex -
perimental settings, though some research 
examines behavior in naturally occurring 
situations. To examine a situational effect, 
researchers usually measure several individ -
uals’ behavior in each of two or more situa -
tions and take the average (across people) of 
the behavior in each situation. For example, 
we might put people in a relaxed, unstruc -
tured situation in which they are free to do 
whatever they want, and a situation that is 
highly structured and includes a difficult job 
that must be completed, and measure how 
talkative people are, on average, in each situ -
ation. Although some people will be more 
talkative than others in each situation—  they 
won’t all act exactly the same way—the situ -
ational approach bypasses these individual 
differences to focus on the average person’s 
behavior in each situation.
When such averages are obtained from 
a sample of people, they can be compared, 
usually with a statistic such as an indepen -
dent groups t -test (if the two situations were 
experienced by different groups of people) 
or a dependent groups t -test (if the two situ -
ations were experienced by the same indi -
viduals). The difference in the averages from 
the two situations reflects a situational in -
fluence on behavior. For example, we might 
find that the average person in the relaxed, 
unstructured situation is more talkative 
than the average person in the highly struc -
tured, task-  oriented situation, suggesting 
that “situational structure” tends to affect 
talkativeness. This is a standard method of 
research in social psychology.
Like dispositionally oriented work, situ -
ationally oriented work also has a venerable 
research tradition. The foundation of this 
tradition is an effort to discover how people 
tend to respond in important ways to vari -
ous experimentally manipulated attributes 
of situations. This approach has served as 
the basis of research programs intended to 
test theories of social behavior and cogni -
tion, such as self-  perception theory (Bem, 
1972), cognitive dissonance theory (Cooper, 