668 vI. SELF‑ AND S OCIAL P ROCESSES
tain situation,” the idea of person–  situation 
interaction grows from two conceptual 
roots—one focusing on people’s disposi -
tions, and the other, on situational factors.
The Dispositional  Roots
The dispositional root is the understanding 
that a person’s behavior is affected by stable 
qualities of that person. For example, wheth -
er a person is generally talkative or quiet is 
determined in part by some quality of that 
person. There is a psychological disposition 
that affects the person’s tendency to behave 
in a talkative and outgoing manner, or con -
versely, in a quiet and reserved manner.
In its traditional form, this view empha -
sizes dispositions that are cross-  situationally 
broad, which means that they affect behavior 
across a wide range of situations. For exam -
ple, according to John, Naumann, and Soto 
(2008), extraversion is a personality trait re -
flecting the degree to which one enacts an 
energetic approach to the social and mate -
rial world, and conscientiousness reflects the 
degree to which one exhibits “socially pro -
scribed impulse control that facilitates task- 
and goal-  directed behavior.” (p. 120). This 
covers a lot of ground. Considering the num -
ber of situations that are part of the social 
and/or material world, and considering that 
many situations involve (or could involve) 
task-  directed and goal-  directed behavior, 
traits such as extraversion and conscientious -
ness are seen as affecting behavior across an 
extremely broad range of situations.
Dispositionally oriented research often fo -
cuses on the way individuals act differently 
from each other, on average, and experience 
different life outcomes. When focused on 
dispositional sources of behavior, a research 
project would ideally begin by measuring a 
person’s behavior in each of several situa -
tions and taking the average. For example, 
a researcher might observe an individual in 
several situations, measure his or her talk -
ativeness in each, and compute his or her 
average talkativeness. Although how much 
the person talks will surely vary from situa -
tion to situation, dispositionally oriented re -
search focuses on average tendencies, or the 
person’s typical or general level of talkative -
ness across situations.
When such averages are obtained for a 
sample of people across one set of situations, they can be correlated with, among other 
things, the same person’s behavior averaged 
across a different  set of situations, or with 
his or her scores on a measure of a relevant 
personality disposition. The first correla -
tion is an index of behavioral consistency, 
reflecting the degree to which the behavioral 
differences among people are consistent 
across sets of situations. The second reflects 
the association between the behavior and 
a specifically identified aspect of personal -
ity— the degree to which the behavioral dif -
ferences among people are related to differ -
ences in a given aspect of their personalities. 
Either way, the results reflect a dispositional 
influence on behavior. This is a standard 
method of research in personality psychol -
ogy.
Dispositionally focused work has gen -
erated a venerable research tradition. 
The foundation of this tradition is an ef -
fort to identify the important personality 
dispositions—  prototypically seen as per -
sonality traits—  that are associated with the 
average behaviors of individuals, calculated 
across situations. Many candidates for “im -
portant” dispositions are available, ranging 
from the 100 items of the California Q -Sort 
(e.g., Block, 2008) to the 61 items of the In -
ventory of the Individual Differences in the 
Lexicon (Wood, Nye, & Saucier, 2010), to 
the 11 “primary trait” scales of the Multi -
dimensional Personality Questionnaire (Tel -
legen & Waller, 2008), to the widely used 
Big Five (e.g., John, Chapter 2, this volume). 
Some of these candidates are highly spe -
cific; others are very general, and the range 
of available content is vast. Allport and Od -
bert (1936) identified 17,953 trait terms in 
the dictionary, and there may be almost that 
many instruments available in the literature 
for measuring personality dispositions.
After identifying relevant dispositions, 
researchers may go in at least two direc -
tions. One direction looks backward in 
time to seek origins of the dispositions. Per -
sonality psychologists have long been inter -
ested in both the environmental roots (e.g., 
early childhood experiences or later expe -
riences of adversity, Rakhshani & Furr, 
2020) and biological roots of personality. 
A particularly intriguing line of research 
is outlining the origins of personality dis -
positions in patterns of early experience as 
they interact with genetic predispositions 