 34. Personality and Subjective Well‑Being 737
punishment and nonreward. Extraverts are 
thought to be higher in BAS strength; thus, 
they should be more sensitive to signals of re -
ward. This reward sensitivity should be ex -
pressed in the form of enhanced information 
processing and increased positive emotions 
when exposed to positive stimuli. Similarly, 
the neuroticism dimension is thought to re -
flect individual differences in BIS strength. 
Thus, neurotics should be more sensitive 
than emotionally stable people to signals of 
punishment.
Tests of these hypotheses have proceeded 
either by ruling out instrumental explana -
tions of the associations (e.g., by determin -
ing whether social activity mediates the as -
sociation between extraversion and positive 
affect; e.g., Lucas, Le, & Dyrenforth, 2008; 
Srivastava, Angelo, & Vallereux, 2008) or 
by examining possible direct links between 
the constructs. For instance, Larsen and 
Ketelaar (1991) showed that extraverts are 
more sensitive than introverts to laboratory- 
based positive mood induction procedures, 
and that neurotics are more sensitive than 
emotionally stable individuals to negative 
mood induction procedures. Lucas and Baird 
(2004) provided meta-  analytic evidence that 
the extraversion effect is not reliable; but 
subsequent research suggests that such reac -
tivity emerges when mood inductions reflect 
appetitive stimuli (Smillie, Cooper, Wilt, & 
Revelle, 2012). Other researchers have used 
paradigms that assess attention to and mem -
ory for positive and negative events (e.g., 
Derryberry & Reed, 1994; Rusting, 1998). 
Finally, researchers have linked these indi -
vidual differences and affective reactions 
through specific psychophysiological pro -
cesses (e.g., Canli, 2004; Depue & Collins, 
1999; Depue & Morrone-  Strupinsky, 2005). 
Theoretical progress on the links between 
these traits and well-being outcomes have 
advanced rapidly in recent years.
Summary
The research we have reviewed in this chap -
ter shows that when studying SWB, person -
ality matters. Happiness, like most person -
ality characteristics, is moderately heritable 
and moderately stable over time. In addi -
tion, happiness has been linked to specific 
personality traits and processes. In fact, the correlations between SWB and personality 
characteristics such as extraversion and neu -
roticism are stronger than correlations with 
any demographic predictor or major life 
circumstance that has been studied so far. 
Thus, a theory of well-being that fails to in -
corporate personality characteristics would 
be incomplete, and much of what we know 
about well-being comes from taking a per -
sonality perspective on the construct.
That being said, some caution is warrant -
ed when interpreting the evidence that has 
been presented in support of personality ef -
fects. For instance, it is important not to in -
terpret strong heritabilities as evidence that 
happiness cannot change. Until researchers 
understand the processes that underlie sta -
ble individual differences in SWB, questions 
about the possibility for change remain un -
answered. In addition, our review suggests 
that researchers should be careful not to 
dismiss effects that may appear at first to 
be quite small, but that have important im -
plications for individual experience. Income 
may only account for about 5% of the vari -
ance in happiness, but this relatively small 
effect can hide the fact that the wealthy are 
considerably happier than individuals who 
live at the poverty level and below. Finally, 
although the stability of SWB over long pe -
riods of time is impressive, it appears that, at 
most, about 35% of the variance reflects a 
stable trait component that does not change 
over time (though the percentage of reliable 
variance is probably higher). In addition, the 
study of major life events shows that signifi -
cant changes in life circumstances can have 
large and lasting effects on happiness. Thus, 
well-being is responsive to life events and 
changing life circumstances—  which leaves 
hope that it can be improved.
Researchers and practitioners hoping to 
use SWB in applied settings are sometimes 
dismayed by the effects described in this 
chapter. But it is important to realize that 
even if there is a reasonable amount of stabil -
ity and strong personality effects, attempts 
to improve overall levels of SWB can still 
be a worthwhile goal. As an analogue, we 
can consider physical health. If it were pos -
sible to construct a purely objective index of 
overall physical health, it is likely that this 
index would be moderately to strongly sta -
ble over time, moderately heritable, and at 
least somewhat related to personality traits. 