Romantic love

Page 618

CHAPTER 32

Romantic Love

Arthur Aron,

Helen E. Fisher,

Greg Strong

Romantic love appears to be a nearly uni-

versal phenomenon, appearing in every cul-

ture for which data are available (Janowiak

& Fischer, 1992) and in every historical

era (Hatfield & Rapson, 2002). Analogs to

romantic love are found in a wide vari-

ety of higher animal species, and love may

well have played a central role in shap-

ing human evolution (Fisher, 1998, 2004).

Romantic love seems to be a key factor in

quality of life generally, being a source of

both some of the greatest joys and some of

the greatest problems, including depression,

rage, stalking, suicide, and homicide (eg,

Ellis & Malamuth, 2000; for a review, see

Meloy, 1998).

Given the prevalence and importance of

romantic love, it is not surprising that it

has been the subject of both artistic and

scholarly attention from the earliest times.

Among the most significant early scholarly

treatments in Western culture is Plato’s Sym-

posium , a systematic analysis of the nature

of love that continues to be influential today

(eg, Aron & Aron, 1991). There has been a

continuous stream of interest in love since

the classical Greeks, with landmarks that

continue to be influential on contemporary

thought, including Stendhal’s (1822/1927)

book-length essay De l’amour and the exten-

sive discussions of the topic by Freud (eg,

1927) and later writers emerging from that

tradition, such as Theodore Reik (1944) and

Carl Jung (eg, 1959/1925). The 19th and

early 20th century also saw interest in love,

including sociologists studying the family

(eg, Westermarck, 1921), cultural anthro-

pologists (eg, Mead, 1928), and clinical

writers outside of the Freudian tradition

(eg, Grant, 1957).

Scholarly work on romantic love in the

last few decades has been primarily centered

in social and personality psychology, largely

starting with the groundbreaking work of

Donn Byrne (1971) and other influential

work on romantic attraction (eg, Hatfield

[Walster], Aronson, Abrahams, & Rottman,

1966) and Berscheid and Hatfield [Walster]’s

(1969) significant distinction between com-

panionate and passionate love. This work

was quickly followed by important contri-

butions of Rubin (1970, 1974) on loving

595

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596 the cambridge handbook of personal relationships

and liking, Dutton and Aron (1974) on the

arousal–attraction effect, and an influential

book on attraction edited by Huston (1974).

The 1980s set the stage for much of the

current thinking on romantic love, includ-

ing the development of lay understandings

of love (Fehr, 1988), the influential exten-

sion of attachment theory to adult love

(Hazan & Shaver, 1987; Shaver & Mikulin-

cer, this volume), Sternberg’s (1986) triangu-

lar theory of love, Tennov’s (1979) descrip-

tive work on intense passionate love, Aron

and Aron’s (1986) self-expansion model of

love, evolutionary psychology approaches

(eg, Buss, 1989), and Hendrick and Hen-

drick’s (1986) adaptation of Lee’s (1977)

model of types of love into a psycho-

metrically solid and widely used multi-

dimensional scale.

These trends from the 1960s through

1980s have all continued and expanded into

the present, with the early 1990s bring-

ing some new strands, such as a stronger

interest in cultural differences (eg, Hat-

field & Rapson, 1996), work on unrecip-

rocated love (Aron, Aron, & Allen, 1998;

Baumeister, Wotman, & Stillwell, 1993), and

love ideals (eg, Fletcher, Simpson, Thomas,

& Giles, 1999; Rusbult, Onizuka, & Lip-

kus, 1993). The major developments in

the late 1990s and early 21st century have

included a new exploration of love as an

emotion (eg, Gonzaga, Keltner, Londahl, &

Smith, 2001) and the dramatic new devel-

opments in the biology of love (eg, Fisher,

1998), notably including most recently the

work on oxytocin and vasopressin in monog-

amous prairie voles (eg, Carter et al.,

1997; Lim, Murphy, & Young, 2004; Young,

Wang, & Insel, 1998), the related work

it has inspired in humans (eg, Gonzaga,

2002), and the recent neuroimaging stud-

ies of romantic love (Aron, Fisher, Mashek,

Strong, Li, & Brown, 2004; Bartels &

Zeki, 2000).

This chapter is an overview of the cur-

rent state of knowledge of romantic love,

noting as appropriate both the sources of the

ideas and the latest thinking and findings. We

conclude with some comments on potential

future directions.

What Is Romantic Love?

In this section, we first review research on

how ordinary people construe love. Then

we turn to how researchers have understood

and measured love, organizing our discus-

sion around the theme of types of love.

How Ordinary People Construe Love

Fehr (1988, 2001) suggested that the long-

standing philosophical controversies over

the meaning of love and the corresponding

diversity of conceptual and operational def-

initions in the scientific literature are due to

the possibility that ordinary people recog-

nize instances of love not by their conform-

ing to some formal definition but rather by

their family resemblance to a prototypical

examplar (just as people seem to recognize

something as a fruit by its similarity to an

apple). Thus, Fehr (1988) adapted Mervis

and Rosch’s (1981) prototype approach to

the topic of love. Specifically, she first had

a group of participants simply list words

that they considered the features of love.

She then took the features listed by more

than one individual and had another sam-

ple rate them for centrality to the concept.

The result was striking agreement across per-

sons in relative centrality of the different fea-

tures, such that some features were central

(eg, caring, intimacy) and others, although

clearly part of the concept, were more

peripheral (eg, butterflies in the stomach,

euphoria). Additional studies demonstrated

that the various prototypical features iden-

tified in this way, and particularly the most

central features, were used by people to rec-

ognize instances of love and that these fea-

tures structured processing and memory for

love-related information.

One line of research emerging from Fehr’s

work has focused on generalizability. Fehr’s

studies were with North American students.

However, replications with other age groups

and in a number of other societies have pro-

duced sets of features of love with clear pro-

totype structures, and in most cases even

the actual content (the particular features

and relative centrality of those features) have

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romantic love 597

been found to be reasonably common across

age groups and cultures (reviewed in Fehr,

2001). Another line of research emerging

from Fehr’s prototype work focuses on the

latent structure of the prototypical love fea-

tures. Across seven studies, Aron and West-

bay (1996) identified and cross-validated

three latent dimensions of these features,

intimacy (which included mainly features

with the highest centrality ratings), commit-

ment (mainly the next most central items),

and passion (mainly the least central items).

Other approaches to how ordinary peo-

ple understand love have included Shaver,

Schwartz, Kirson, and O’Connor’s (1987)

prototype work in which they found that

love and joy are related or similar, but love

is more personalized toward the object of

affection, whereas joy is more general in

nature. They also noted that people describe

love as a form of social contact that is highly

specific and focused on the love object, a

desire to be near to, to touch, kiss (and

so forth) the loved person. Yet another

approach has been to focus not on proto-

typical features but on prototypical kinds of

love. Thus Fehr and Russell (1991) found that

maternal and friendship love were prototyp-

ical of love in general, but romantic and sex-

ual love were not.

In sum, it appears that people have a com-

mon understanding of what love means in

terms of its resemblance to a set of proto-

type features, that this kind of understanding

is found almost everywhere, although there

are some differences in its content across

cultures; that in North American culture the

central features tend to be related to inti-

macy, the next most central to commitment,

and the more peripheral to passion; and that

romantic love is not the most prototypical

of love in general.

Scientific and Scholarly Delineations:

Types of Love

Scientific and scholarly work on the nature

of love has mainly emphasized identify-

ing and differentiating subspecies or aspects

of love. Most centrally is the distinction

between romantic love (the focus of this

chapter) and more general kinds of love,

such as familial love, compassionate love for

strangers, love of God, or love of country.

As noted, the focus of this chapter is on

romantic love, love in the context of roman-

tic relationships–that is, relationships of the

kind that typically have an explicit actual

or potential sexual component, such as dat-

ing and marital relationships. Aron and Aron

(1991) defined love as “the constellation of

behaviors, cognitions, and emotions associ-

ated with a desire to enter or maintain a

close relationship with a specific other per-

son”(p. 26).

With regard to the relation of roman-

tic love to other relationship constructs,

Rubin (1970) explicitly distinguished lov-

ing from liking, and developed a measure

that included separate scales for each. His

13-item love scale emphasizes dependence,

caring, and exclusiveness and was validated

in part by showing that college dating cou-

ples who scored higher on the scale gazed

longer into their partner’s eyes. His paral-

lel liking scale, on the other hand, empha-

sizes similarity, respect, and positive evalua-

tion. Importantly, the two scales were only

moderately correlated. Indeed, in one study

(Wong, 1989), intensity of unrequited love

was positively correlated with the love scores

and negatively correlated with liking scores.

Rubin’s scale has been widely used, and

other researchers have found the conceptual

distinction between liking and loving to be

very useful (eg, Davis & Todd, 1985; Stern-

berg, 1987).

Turning specifically to romantic love, a

key distinction has been between passion-

ate and companionate love. Berscheid and

Hatfield [Walster](1978) defined the first

as “a state of intense longing for union with

another”(p. 9). They defined companion-

ate love as “the affection we feel for those

with whom our lives are deeply entwined”

(p. 9). Based on their definition of pas-

sionate love, Hatfield and Sprecher (1986)

developed a Passionate Love Scale (PLS).

Example items include “I would rather be

with than with anyone else” and “I melt

when looking deeply into’s eyes.” The

PLS has been used successfully in a wide

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598 the cambridge handbook of personal relationships

variety of studies, including studies that dis-

tinguish what it measures from companion-

ate love (Sprecher & Regan, 1998); most

recently, it was used in an functional mag-

netic resonance imaging (fMRI) study in

which PLS scores correlated with activa-

tion in a region of the caudate associated

with reward (Aron, Fisher, et al., 2004). The

distinction between companionate and pas-

sionate love also maps on to a related dis-

tinction people have been shown to make

between those whom they “love” and the

subset of these with whom they are “in love,”

for whom they also typically report sexual

desire (Myers & Berscheid, 1997).

There has been little explicit attention

devoted to companionate love except as a

conceptual counterpoint to passionate love.

Thus, for example, Masuda (2003) con-

ducted a meta-analysis comparing correla-

tions of passionate and companionate love

with satisfaction involving more than 33

studies by using a variety of measures to rep-

resent each construct (for passionate love

measures, the mean disattenuated correla-

tion with satisfaction was 0.64; for compan-

ionate love measures, the correlation was

either 0.34 for studies using measures of

“friendship love,” or 0.72, for studies using

other measures such as Rubin’s liking or lov-

ing scales and measures of intimacy).

Another influential categorization fo-

cuses on “love styles.” This was originally a

circumplex model of three central and three

secondary love types, based on a combina-

tion of historical conceptions and empiri-

cal analysis of interview reports (Lee, 1977).

However, most research applications have

employed the Hendrick and Hendrick (1986,

2003) measure, which treats Lee’s styles as

six relatively independent dimensions: eros

(romantic, passionate love), ludus (game

playing love), storge (friendship love),

pragma (logical,“shopping-list” love), mania

(possesive, dependent love), and agape (self-

less love).

Yet another influential categorization of

romantic love was developed by Sternberg

(1986), based on his attempt to integrate

the existing psychology and related litera-

tures. Sternberg offers a triangular theory,

which conceptualizes love in terms of inti-

macy, commitment–decision, and passion.

Sternberg treated these three components

as ingredients that in various combinations

define types of love, such as “romantic love”

(the combination of high intimacy, low

commitment, and high passion) or “fatu-

ous love”(high passion, low intimacy, and

high commitment). Sternberg’s three com-

ponents correspond reasonably well with

Aron and Westbay’s (1996) later empiri-

cal identification of latent dimensions of lay

conceptions of love and Sternberg’s concep-

tualization has been independently influen-

tial (eg, Acker & Davis, 1992). However,

research using this conceptualization has

been hampered by the lack of a strong mea-

sure. The questionnaire Sternberg (1997)

developed has been difficult to use because

of problems of discriminant validity among

the scales assessing the three components

(eg, Whitley, 1993).

Hendrick and Hendrick (1989) factor ana-

lyzed many of the measures of love based

on the typologies we have considered (as

well as some others) and identified five latent

dimensions. The first two factors, which

accounted for most of the variance (34 and

14%), Fehr (2001) identified with passionate

and companionate love, respectively. Hen-

drick and Hendrick commented that the

last three factors are “less important but

deserve mention”(p. 791). Factor 3 could

be described as manic or ambivalent love,

Factor 4 as security–closeness, and Factor

5 as a kind of solid, practical, nonerotic,

friendship love.

Before concluding this section, we should

also note that some of the relationship qual-

ities identified as a part or type of love,

also have often been distinguished from love.

One such construct is commitment. Fehr

(1988) demonstrated that lay conceptions of

love and commitment are overlapping but

not identical; Fehr’s (2001) review of stud-

ies using measures of people’s experience

of the two constructs in actual relationships

yielded a similar conclusion. Another such

construct is closeness and intimacy (for a fur-

ther distinction of closeness vs. intimacy, see

Aron & Mashek, 2004). An interesting

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romantic love 599

theoretical suggestion is that passionate love

is a function of the rate of change in close-

ness (Aron & Aron, 1986) or rate of change in

intimacy (Baumeister & Bratslavsky, 1999).

However, there are no studies to date

directly testing these predictions, and both

closeness and intimacy seem tightly linked to

love (eg, Aron & Westbay [1996] found that

the intimacy dimension was most central to

the prototype of love, and Aron & Fraley

[1999] found that closeness was highly cor-

related with measures of love).

One way to summarize much of this lit-

erature is in terms of passion, intimacy, and

commitment. Passionate love has been dis-

tinguished from the outset from compan-

ionate love; it appears as a distinct factor

in analyses of lay features of love; it is a

strong factor when considering diverse mea-

sures of love; it is described as one of the

three components in Sternberg’s system; and

it is described as eros or mania in Lee’s

and the Hendricks’ system. Other types of

romantic love are less clear-cut. Compan-

ionate love seems to comprise a combina-

tion of commitment and intimacy, is perhaps

deeply linked with relationship satisfaction

more generally, and seems strongly linked

with types of love including friendship love,

practical love, and all-giving (agape) love.

Because most of these other topics have

entire chapters devoted to them elsewhere

in this volume (ie, chapters on commit-

ment and satisfaction), the main focus of

this chapter is on romantic love (the pas-

sionate love aspect), although we continue

to refer briefly to companionate love when

there are unique relevant findings or think-

ing that may not be covered elsewhere in

this volume.

The Biological Basis of Romantic Love

Based on a review of the relevant biological

literature, Fisher (1998) hypothesized that

avian and mammalian species have evolved

three distinct brain systems for courtship,

mating, reproduction, and parenting:(a) the

sex drive, characterized by a craving for sex-

ual gratification;(b) attraction (“favoritism,”

“sexual preference,” or “mate choice”), char-

acterized by focused attention on a preferred

partner, heightened energy, motivation, and

goal-oriented courtship behaviors; and (c)

attachment, characterized by the mainte-

nance of proximity, affiliative gestures, and

expressions of calm when in social contact

with a mating partner and separation anxi-

ety when apart (as well as parental behav-

iors such as territory defense, nest build-

ing, mutual feeding, grooming, and other

parental chores). Each emotion–motivation

system is associated with a different con-

stellation of brain circuits, different behavior

patterns, and different affective states; each

emotion–motivation system varies accord-

ing to the reproductive strategy of each

species; and each emotion–motivation sys-

tem evolved to play a different role in

courtship, mating, reproduction, and par-

enting. The sex drive evolved principally to

motivate individuals to seek sexual union

with a range of partners. Attraction evolved

to motivate individuals to prefer particular

mating partners and focus their courtship

attention on these mates, thereby mak-

ing a mate choice. The system for adult

male–female attachment evolved primarily

to motivate individuals to sustain affilia-

tive connections long enough to complete

species-specific parental duties.

From the perspective of the present chap-

ter on human romantic love, we can equate

Fisher’s “attraction” with passionate love and

Fisher’s “attachment” with companionate

love.(We return later to the issue of the dis-

tinction between the sex drive and roman-

tic love.)

The Biology of Passionate Love

It is well established that many creatures

have mate preferences and make mate

choices. The phenomenon of mate choice

is so common that the ethological litera-

ture regularly uses several terms to describe

it, including “mate choice,”“female choice,”

“mate preference,”“individual preference,”

“favoritism,”“sexual choice,” and “selective

perceptivity.” Fisher (1998; Fisher et al.,

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600 the cambridge handbook of personal relationships

2002) argued that this brain system has a

specific and distinct constellation of neural

correlates; that this system operates in tan-

dem with other neural systems, including

the sex drive and specific sensory circuits

for mate discrimination; that it is expressed

at different times and to different degrees

according to each species’ specific repro-

ductive strategy; and that this brain sys-

tem evolved to enable the chooser to dis-

criminate between courtship displays, prefer

those that advertise superior genes, better

resources, or more parental investment, and

motivate the chooser to focus his or her

courtship attention on and pursue specific

mating partners.

In most species of mammals and birds,

this excitatory state of attraction is brief.

Feelings of attraction last only minutes,

hours, days, or weeks. In humans, Fisher

argued, the neural mechanism for attraction

is more developed, forming the physiologi-

cal basis of what is commonly known as pas-

sionate love, obsessive love, or romantic love.

Ethologists generally lump this system,

attraction, with the sex drive and call

this behavioral–physiological state “procep-

tivity.” There are exceptions. Beach (1976)

made a distinction between the sex drive

and attraction, writing,“The occurrence or

non-occurrence of copulation depends as

much on individual affinities and aversions

as upon the presence or absence of sex

hormones in the female”(p. 131). More-

over,“proceptive and receptive behavior

may depend upon different anatomical and

neurochemical systems in the brain”(p. 131).

Goodall (1986) wrote that “partner prefer-

ences, independent of hormonal influences,

are clearly of major significance for chim-

panzees”(p. 446).

Few scientists have considered the

anatomic and neurochemical mechanisms

that produce mate choice (see Fisher

et al., 2002). However, Beach (1976)

and Liebowitz (1983) proposed that the

neurotransmitters associated with arousal,

dopamine, or norepinephrine (or a combi-

nation of these) may be involved. Fisher

(1998) hypothesized that attraction (roman-

tic love) may be associated with elevated

activity of the brain’s dopamine or nore-

pinephrine and decreased activity of the

brain’s serotonin. These hypotheses are con-

sistent with considerable correlational evi-

dence. Characteristics of intense passionate

love include focused attention, strong moti-

vation, goal-oriented behaviors, heightened

energy, sleeplessness, loss of appetite, feel-

ings of euphoria, obsessive thinking about

the beloved, and heightened attraction dur-

ing adversity in the relationship (eg, Ten-

nov, 1979). Each of these characteristics are

associated with elevated activities of central

dopamine and norepinephrine or decreased

activity of central serotonin in the corre-

sponding brain regions (Flament, Rapoport,

& Bert, 1985; Hollander et al., 1988; Schultz,

2000; Thoren, Asberg, & Bertilsson, 1980;

Wise, 1989; see Fisher 1998). Passionate

attraction takes a variety of graded forms,

however, ranging from romantic love that

is returned to unrequited love. So it is

expected that these gradations of attraction

are associated with different combinations

of dopamine, norepinephrine, and serotonin,

as well as with the activities of many other

neural systems (Fisher, 1998).

Data from animal studies also support the

hypothesis that elevated activities of cen-

tral dopamine play a primary role in attrac-

tion in mammalian species. In rats, block-

ing the activities of dopamine diminishes

specific proceptive behaviors, including hop-

ping and darting (Herbert, 1996). Further,

when a female lab-raised prairie vole is

mated with a male, she forms a distinct pref-

erence for this partner. This preference is

associated with a 50% increase of dopamine

in the nucleus accumbens (Gingrich, Liu,

Cascio, Wang, & Insel, 2000). In fact, when a

dopamine antagonist is injected directly into

the nucleus accumbens, females no longer

prefer this partner and when a female is

injected with a dopamine agonist, she begins

to prefer a conspecific who is present at

the time of infusion, even if the female

has not mated with this male (Aragona,

Yan, Curtis, Stephan, & Wang, 2003; Wang

et al., 1999).

Two recent studies using fMRI lend rel-

atively direct support to the dopamine

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romantic love 601

hypothesis in humans. fMRI technology

scans the brain to register blood flow changes

in any or all brain regions that are either

increasing or decreasing their metabolic

activities. Bartels and Zeki (2000) scanned

a group of participants who reported being

“truly, deeply, and madly in love”(p. 3829),

and compared brain activation when looking

at the beloved partner versus when looking

at familiar friends. They found a specific con-

stellation of brain activity associated with

looking at the beloved, including activity in

the caudate nucleus. The caudate nucleus is

largely associated with motivation and goal-

oriented behaviors; 80% of receptor sites for

dopamine reside here, and the caudate is a

central part of the brain’s “reward system,”

the system associated with the identification

of, focus on, and motivation to win rewards.

These data suggest that passionate romantic

love is primarily a motivation system associ-

ated with dopamine pathways in the reward

system of the brain.

Aron, Fisher, et al.(2004) conducted a

similar study, but their participants were

more recently and even more intensely in

love than those in the Bartels and Zeki study.

(In the Aron et al. sample, mean time in

love was 7 months and mean PLS score was

8.54 on a 9-point scale; in the Bartels and

Zeki sample, the corresponding means were

29 and 7.55 months). In the Aron et al.

study, comparison of activations when look-

ing at and thinking about a beloved (vs. look-

ing at and thinking about familiar neutral

individual) again yielded significant activa-

tion in the caudate. Indeed, in this study,

the caudate activation was especially strong.

Further, Aron et al. found that this cau-

date activation was significantly correlated

(0.60) with scores on the PLS.(Bartels &

Zeki did not test this correlation.) Most

important, Aron et al. also found signifi-

cant activity in the right ventral tegmental

area, a region primarily associated with the

production and distribution of dopamine to

several other brain regions. These data fur-

ther suggest that dopamine plays a central

role in the focused attention, motivation,

and goal-oriented behaviors associated with

romantic love.

In sum, the considerable data on mate

preference in mammalian (and avian)

species, and the association of this mate

preference with subcortical dopaminergic

pathways in human and animal studies sug-

gest that attraction in mammals (and its

human counterpart, romantic love) is a spe-

cific biobehavioral brain system; that it is

associated with at least one specific neuro-

transmitter, dopamine; and that this brain

system evolved to facilitate a specific repro-

ductive function: mate preference and pur-

suit of this preferred mating partner.

The Biology of Companionate Love

As noted earlier, companionate love overlaps

with intimacy and commitment and general

relationship satisfaction, topics treated else-

where in this volume. Thus, the focus of this

chapter is mainly on passionate love. Never-

theless, we should mention that there has

been some important work on love more

generally, specifically on adult male–female

attachment behaviors in other mammalian

species and fMRI data on maternal love

in humans.

Several brain chemicals have been impli-

cated in male–female bonding, group bond-

ing, and mother–infant bonding in mammals

(see Pedersen, Caldwell, Peterson, Walker, &

Mason, 1992). Recent data indicate that oxy-

tocin and vasopressin are the primary neu-

rohormones associated with monogamous

male–female attachment and monogamous

parenting behaviors in mammals (Carter

et al., 1997; Lim et al., 2004; Young et al.,

1998;). Moreover, the distribution of recep-

tor sites associated with these neurohor-

monal systems in the brain are directed

by specific genes (Lim et al., 2004; Young,

Nilsen, Waymire, MacGregor, & Insel, 1999)

and these systems vary from one species

to the next, contributing to species dif-

ferences in male–female attachment (Lim

et al., 2004).

Recent fMRI studies of humans have also

begun to record the brain regions associated

with maternal love (Bartels & Zeki, 2004;

Swain et al., 2004), and some of these results

suggest that central oxytocin and vasopressin

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602 the cambridge handbook of personal relationships

systems also play a role in mother–infant

attachment (Bartels & Zeki, 2004; Leckman

et al., 2004). Researchers are beginning to

pinpoint some of the neural mechanisms

that most likely contribute to human attach-

ment, specifically male–female companion-

ate love and maternal love.

The Course of Love

Initial Attraction

Other chapters in this volume focus on

attraction (see also Berschied & Reis, 1998)

and courtship (see especially Surra, Gray,

Boettcher, Cottle, & West). Thus, we review

only briefly the extensive literature on

romantic attraction, focusing specifically on

the especially intense attractions commonly

referred to as “falling in love.”

Research over the years has identified sev-

eral factors that lead to general liking, which

also have been found to play a role in specif-

ically romantic attraction. These include

reciprocal liking (discovering that the other

likes the self; eg, Walster & Walster, 1963);

desirability of the other (kindness, intel-

ligence, humor, good looks, social status,

etc.; eg, Buss, 1989); similarity, especially

of attitudes, personality, and demographic

characteristics (eg, Byrne, 1971; Laumann,

Gagnon, Michael, & Michaels, 1994; Rush-

ton, 1989); exposure (eg, Zajonc, 1968);

and social appropriateness, support, and

encouragement from one’s social network

(eg, Sprecher et al., 1994).

In the specific context of falling in love,

reciprocal liking and desirability of the part-

ner appear to be the most influential (Aron,

Dutton, Aron, & Iverson, 1989), even across

cultures (Buss, 1989; Sprecher et al., 1994).

For example, Aron et al.(1989) reported that

in their sample of Canadian college students

who very recently fell in love, approximately

90% of accounts mentioned some indicator

of perceiving the other was attracted to the

self (with eye contact being a particularly

common reported cue) and approximately

78% of accounts mentioned desirable char-

acteristics. They commented that these data

suggest “people are just waiting for an attrac-

tive person to do something they can inter-

pret as liking them”(p. 251).

Among desirable characteristics, across

many cultures, kindness and intelligence

(Buss, 1989) seem to be especially important

for both women and men. Men and women

do seem to vary in their mate preferences,

however. Men are somewhat more likely to

be attracted to women who show visual signs

of youth, health, and beauty; women tend

to be somewhat more attracted to men who

exhibit signs of status and resources (eg,

Buss, 1989; Li, Bailey, & Kenrick, 2002).

Regarding similarity, perceived shared

attitudes plays a highly consistent role across

many experiments (Byrne, 1971), but when

other variables are also free to vary, the

effect sizes are often relatively small (eg,

Newcomb, 1956). Further, much of the

effects may be due to reduced attraction

to perceived dissimilars (Rosenbaum, 1986).

It is also clear that perceived similarity is

much more important than actual similarity

(Berscheid & Reis, 1998). Personality sim-

ilarity seems to play a much smaller role

(Botwin, Buss, & Shackelford, 1997; Caspi

& Herbener, 1993). In general dissimilarity

(“opposites attract”) seems to play little posi-

tive role in attraction, although there is some

evidence that when one believes a relation-

ship with an appropriate other is likely, one

may prefer dissimilars over similars (Aron,

Steele, & Kashdan, 2005).

Exposure or “propinquity” may function

mainly as providing an opportunity. There is

little direct evidence for it playing much of a

direct role in falling in love (Aron et al., 1989;

Sprecher et al., 1994), although the possibil-

ity that platonic friendships are a common

beginning for romantic relationships given

the romantic attractions they often include

(Kaplan & Keys, 1997) may be due to such

an effect.

Social appropriateness and the impact of

social networks has been relatively unex-

plored. Sprecher et al.(1994) found that

social networks play a more important

role in Japanese than in American culture,

perhaps consistent with the former being

more collectivist. There is some evidence in

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romantic love 603

American culture for a “Romeo and Juliet

Effect” in which romantic love is inversely

correlated with parental approval (Driscoll,

Davis, & Lipetz, 1972); however, most stud-

ies support the more universal pattern of

parental approval being a positive factor

(Sprecher, Felmlee, & Orbuch, 2002).

In addition to these general attraction

variables, Aron et al.(1989) argued that

there are at least three variables that appear

to be specific to falling in love: arousal at

time of meeting the partner (the “arousal–

attraction effect”), readiness for falling in

love, and “specific cues.” The arousal–

attraction effect has been demonstrated in

a series of experiments including the Dut-

ton and Aron (1974)“shaky bridge” study in

which male participants were more attracted

to a good-looking confederate when the par-

ticipant met her on an anxiety-provoking

suspension bridge than when they met her

on a solid, low bridge. Subsequent studies

(see Foster, Witcher, Campbell, & Green,

1998) have demonstrated the generalizabil-

ity of the effect under a great variety of

positive and negative sources of arousal,

as well as supporting at least two mecha-

nisms (reattribution of arousal and eliciting

of a dominant response). One recent study

(Lewandowski & Aron, 2004) showed the

effect generalizes across women and men

and holds even when the partner is not a

confederate.

The main direct support for a readiness

effect comes from the Aron et al.(1989)

study in which it was mentioned with mod-

erate frequency in accounts of falling in love

and the Sprecher et al.(1994) cross-cultural

study in which Russian, Japanese, and US

participants all rated it as being moderately

important for falling in love. Indeed, it seems

reasonable that people are less likely to fall

in love with Person A when they have just

fallen in love with Person B and may be more

likely to fall in love when they have just bro-

ken up with someone.

The role of specific cues was first sug-

gested by Binet (1887), the inventor of the

intelligence test, who noted that individuals

are often strongly attracted to others with

some very specific characteristic (a color of

hair, shape of face, way of walking, etc.), a

theme extended by Grant (1957). Aron et al.

(1989) found a number of accounts of falling

in love that seemed especially well explained

by such a phenomenon; perhaps consistent

with studies showing that people often select

romantic partners similar to their parents

(eg, Aron et al., 1974; Little, Penton-Voak,

& Burt, 2003).

Effects of Falling in Love

Taking a largely qualitative approach, Ten-

nov (1979) studied individuals who reported

intense romantic love. As noted earlier,

such individuals commonly report focused

attention, strong motivation, goal-oriented

behaviors, heightened energy, sleeplessness,

loss of appetite, feelings of euphoria, obses-

sive thinking about the beloved, and height-

ened attraction during adversity in the rela-

tionship, characteristics that correspond well

with those emphasized in Hatfield and

Sprecher’s (1986) PLS described earlier.

Is falling in love a good thing? Based

on the self-expansion model (Aron, Aron,

& Norman, 2001, reviewed below), Aron,

Paris, and Aron (1995) predicted that falling

in love, when reciprocated, would lead to an

enhancement of the self-concept, including

increased identity domain, greater sense of

self-efficacy, and greater self-esteem. They

studied two large samples of mainly first-

and second-year US college students, col-

lecting data every 2 weeks over the first 10

weeks of the fall term. In both studies, at

each testing participants completing a series

of items about what had happened in the

last 2 weeks, among which were items about

whether they had fallen in love. In addition,

in the first study, at each testing, they also

answered an open-ended question “Who are

you today?”; in the second study, they com-

pleted standard self-efficacy and self-esteem

scales. About 25% of participants fell in love

at some point over the 10 weeks. The key

results were that participants who fell in

love showed significant increases in diver-

sity of the self-concept and increased self-

efficacy and self-esteem from the testing ses-

sion before to the testing session after they

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604 the cambridge handbook of personal relationships

fell in love. These changes were significantly

greater than the changes across other testing-

to-testing periods for the participants who

fell in love and also significantly greater than

the average testing-to-testing changes for the

participants who did not fall in love. Fur-

ther, all of these results remained significant

even after statistically controlling for mood

changes associated with falling in love.

Unreciprocated Love

Of course, falling in love need not result

in it being reciprocated. Baumeister et al.

(1993) compared autobiographical accounts

of being rejected and of being the object of

someone’s undesired attraction. They found

that rejection can lead to strong organization

as well as strong disorganization of thoughts,

behaviors, and emotions; both the rejector’s

and rejectee’s behaviors are mostly passive;

and both wish (but don’t necessarily act) for

different behaviors and outcomes from the

other and both usually end up disappointed.

Aron et al.(1998) found that intensity

of unrequited love was predicted by three

factors. The most important was perceived

desirability of the partner and the relation-

ship (eg, high ratings for “How perfect is

this person in your eyes?”); the second most

important was perceived desirability of the

state of being in love, whether reciprocated

or not (eg,“How fulfilling is it to love this

person even though it is unrequited?”); and

the least important (but still significant) was

mistakenly believing at the outset that the

other would reciprocate the love (eg,“Even

though you don’t feel this person loves you

as much as you would like, to what extent

has this person done things that would

make most people think he or she loves

you?”). Aron et al.(1998) also found dif-

ferences by self-reported attachment style.

Secure individuals were least likely to expe-

rience unrequited love; when they did, they

were the group with the strongest associa-

tion with mistaken expectation of recipro-

cation. Avoidant individuals were the next

most likely to experience unrequited love;

when they did, they were the group with

the strongest association with desirability of

the state of being in love. Finally, anxious–

ambivalent individuals were the most likely

to experience unrequited love and were the

group with the strongest association with

desirability of the partner (indeed, it was

extremely strong for them, and intensity for

them was negatively associated with desir-

ability of the state of being in love).

Maintaining Love Over Time

Relationship satisfaction and measures of

companionate love generally show declines

over time after the initial relationship period

(Karney & Bradbury, 1995; Tucker & Aron,

1993). Indeed, one 5-year longitudinal study

of dating couples (Sprecher, 1999) found

that although reports of love declined over

each year, participants at the end of each

year reported that they loved their partner

more. Thus, it is possible that either people

believe that love increases even when it does

not (consistent with Karney & Frye’s [2002]

findings on recall of satisfaction), or perhaps

the meaning of love changes so that what was

considered love last year is now considered

a shallow affection.

In any case, with regard to passionate

love, the general view among love theo-

rists has been that if a romantic relationship

persists over time, passionate love declines

over the first couple years (eg, Huesman,

1980; Sternberg, 1986), and, if things are

going well, companionate love correspond-

ingly increases (eg, Berscheid & Hatfield

[Walster], 1969; Sternberg, 1986), creating

perhaps a “warm afterglow”(Reik, 1944).

Consistent with this view, cross-sectional

data show that passionate love is higher at

marriage than either just before the birth

of a couple’s first child or just before the

last child leaves home, and longitudinal data

show that it is higher before than after mar-

riage (Tucker & Aron, 1993) and from the

first to second year of marriage (Traupmann

& Hatfield, 1981; Utne, 1977). Pineo (1961)

found declines in self-report items of phys-

ical attraction and romantic feeling in 400

married couples from engagement to 20

years later.

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romantic love 605

Several theories have been offered to

explain the general decline in passionate

love over time. One approach emphasizes

habituation (eg, Aronson & Linder, 1965;

Berger, 1988; Huesmann, 1980). Another

view emphasizes the evolutionary value of

passionate love for initiating and maintaining

the relationship over the early stages, or long

enough to conceive a child (eg, Fisher, 1998,

2004). Yet another perspective emphasizes

that passion arises from the rapid develop-

ment of the relationship. Thus, Aron and

Aron (1986) argued that passion arises from

the intensity of the rapid self-expansion that

occurs in the formation of a relationship as

one comes to include the other in the self;

after the other is largely included, the rate of

expansion inevitably slows down. Baumeis-

ter and Bratslavsky (1999) offered a similar

model, emphasizing that passion is a func-

tion of the rate of increase in intimacy and

that as intimacy plateaus, passion decreases.

Nevertheless, while passionate love (and

satisfaction and love of all kinds) gen-

erally declines over time, the view that

passionate love inevitably declines has not

been demonstrated. It is certainly clear that

many long-term couples experience high

levels of satisfaction (eg, Cuber & Har-

roff, 1965). Indeed, in a 4-year longitudinal

study of newlyweds, Karney and Bradbury

(1997) found that about 10% maintained

or increased their level of satisfaction. Per-

haps more surprising, several cross-sectional

studies have found a small percentage of

individuals in long-term relationships of 20

years or more report very high levels of pas-

sionate love (reviewed in Tucker & Aron,

1993). Preliminary results of an interview

study (Acevedo & Aron, 2005) suggest that

at least some such reports may correspond to

how the relationship is actually being expe-

rienced and not due merely to response bias

or self-deception. Further, Aron, Norman,

Aron, McKenna, and Heyman (2000) were

able to increase reported passionate love (at

least temporarily) in long-term relationship

partners through an experimental task, sug-

gesting there may be natural mechanisms

that permit high levels of passionate love

even in long-term relationships.

How Does Love Work?(Models

of Love Processes)

In this section, we briefly review seven

approaches that have been particularly influ-

ential in specifically focusing on understand-

ing the dynamics of romantic love in general,

and especially with regard to passionate love.

Other important theoretical approaches in

the relationship area, such as interdepen-

dence theory (Kelley & Thibaut, 1979),

have only rarely been applied specifically to

romantic love (eg, Kelley, 1983; Rusbult

et al., 1993)

Cultural Models

As noted at the outset, romantic love has

been observed in every culture in which

observers have reported on relevant topics

and in every era of human history (Fisher,

2004; Hatfield & Rapson, 2002; Jankowiak

& Fischer, 1992). However, the extent to

which it is valued by a culture, the role it

plays in marriage, and the traditional exem-

plars and narratives seem to differ greatly

across cultures (eg, Dion & Dion, 1988,

1996; Hatfield, Martel, & Rapson, in press;

Hatfield & Rapson, 1996; Hendrick & Hen-

drick, 2003). For example, Dion and Dion

focused on individualism and collectivistic

views or attitudes. They argued that individ-

ualistic people may have a difficult time lov-

ing and becoming intimate with each other.

The high divorce rate in the United States

may be due to exaggerated feelings of indi-

vidualism. As another example, Sprecher

et al.(1994) compared love experiences of

college students in the United States, Japan,

and Russia. Across the three cultures, most

participants had been in love at least once,

erotic love was the most common style, most

believed that love should be the basis of mar-

riage, and desirable personality and physi-

cal appearance and reciprocal liking were

most important for falling in love. There

were also differences: Americans had more

secure attachment, were higher on the eros

and storge love styles and on passionate love,

and considered physical appearance and sim-

ilarity more important for falling in love.

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606 the cambridge handbook of personal relationships

Russians scored higher on avoidant attach-

ment, ludus love style and agape style, and

were most willing to marry someone they

didn’t love romantically (41% of Russian

women and 30% of Russian men reported

that); Russians rated familiarity high but per-

sonality and similarity low as reasons they

had fallen in love. Japanese were least likely

to be in love at the time and more likely

to have never been in love; they had more

avoidants, were less romantic, and consid-

ered social standing more important.

Overall, these examples and other stud-

ies of cultural (and subcultural) differences

and similarities (eg, Contreras, Hendrick, &

Hendrick, 1996; Doherty, Hatfield, Thomp-

son, & Choo, 1994; Kim, Hatfield, & Kim,

2004; Levine, Sato, Hashimoto, & Verma,

1995; Simmons, vom Kolke, & Shimizu,

1986) suggest that there is a core element

of passionate love that arises in every cul-

ture and that may even have an evolution-

ary foundation, but how it is enacted may

depend heavily on the cultural context.

Love As Emotion

Many emotion theorists have treated love

as an emotion (eg, Gonzaga et al., 2001)

or even as a basic emotion (Shaver, Mor-

gan, & Wu, 1996; Shaver et al., 1987), not-

ing, for example, that it is typically the first

response given when participants are asked

for an example of an emotion and, partic-

ularly when one focuses on “moments of

love,” it shows many of the features of emo-

tions. On the other hand, Aron and Aron

(1991) argued that although love is highly

emotional, it may be better characterized as

a goal-oriented motivational state and not as

a specific emotion in its own right, given that

it tends to be hard to control, is not asso-

ciated with any specific facial expression,

and is focused on a specific reward. To date,

this latter view is supported by two lines of

research. First, in various studies (Acevedo

& Aron, 2004a; Rousar, 1990) asking partici-

pants to check the emotions one feels or has

felt when experiencing “love”(or “roman-

tic love,”“passionate love,” or a “moment

of passionate love”), many more emotions

are checked than are checked for fear, anger,

sadness, or happiness; in each case, there

were also more opposite valence emotions

checked when rating experiences of love

than experiences of fear and so forth. These

results were predicted based on the idea that

like other goal oriented states, love gener-

ates a variety of specific emotions according

to the extent to which it is satisfied or frus-

trated. The second line of work is the recent

fMRI studies of romantic love (Aron Fisher

et al., 2005; Bartels & Zeki, 2000), which,

as noted earlier, found activation across par-

ticipants primarily in reward-related brain

regions, with greater diversity of response in

emotion-related regions.

At this point it seems clear that passionate

love has a strong motivational component

and functions much like a goal state. Never-

theless, it remains possible that love may also

be a specific emotion or represent a specific

motivational experience. Of course, both a

constellation of emotions and several moti-

vations are clearly involved, and definitions

of what are called emotions versus motiva-

tions are somewhat overlapping.

Love As Sex

Ellen Berscheid (1988) made the influen-

tial comment that passionate love is “about

90% sexual desire unfulfilled.” Clearly, sex-

ual desire plays a significant role in pas-

sionate love. For example, in the lay pro-

totype of love developed by Fehr (1988),

many of the features identified by Aron and

Westbay (1996) as part of the passion fac-

tor are sexual in nature, including sexual

passion, sex appeal, and physical attraction.

Similarly, the PLS Scale, the most widely

used measure of passionate love, includes

items that emphasize sexual desire, includ-

ing “I sense my body responding when

touches me,”“In the presence of, I yearn to

touch, and be touched,” and “Sometimes my

body trembles with excitement at the sight

of”–all items that correlate highly with

the other scale items.

Nevertheless, it does seem possible to dis-

tinguish passionate love from sexual desire.

Conceptually, Aron and Aron (1991) argued

that understandings of passionate love and

sexuality fall on a continuum from love

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romantic love 607

being the cause of sex to sex being the cause

of love. In terms of evolutionary foundations,

as noted earlier, Fisher (1998) argued that

romantic attraction and the sex drive are

associated with distinct brain systems and

that each evolved to facilitate a different

aspect of courtship, mating, and reproduc-

tion. Several studies also support their being

such a distinction. Gonzaga et al.(2001)

found positive correlations between love and

sexual desire, but also that there are differ-

ent cues and different behavioral responses.

Another relevant line of thinking is Dia-

mond’s (2003) argument that sexual orien-

tation does not completely predict the gen-

der of objects of passionate love and that

individuals sometimes appear to fall in love

with partners of the “wrong” gender with

whom they may have no initial desire to

have sexual contact, even though they show

all the other symptoms of passionate love.

Finally, the two fMRI studies of romantic

love (Aron Fisher et al., 2005; Bartels &

Zeki, 2000) found activations that only min-

imally overlapped with activations that have

been found in studies of sexual arousal (eg,

Arnow et al., 2002; Karama et al., 2002).

In sum, sexuality almost surely plays an

important role in passionate love, but it

is also conceptually and empirically distin-

guishable from it and cannot fully explain

its functioning.

Love As Attachment

Attachment theory (Bowlby, 1969; Shaver

& Mikulincer, this volume) has been among

the most influential approaches to under-

standing romantic love and is the primary

approach that emphasizes individual differ-

ences. The theory posits that love develops

out of three behavioral systems that evolved

to promote development and survival of

infants in humans and perhaps other pri-

mates or even other species (Shaver, Hazan,

& Bradshaw, 1988). These systems include

attachment, caregiving, and sexuality. In

human adults, according to this model, pas-

sionate love is a combination of the desire

for attachment and sexuality.(Companion-

ate love develops out of these systems plus

the caregiving system.) Further, this model

emphasizes that early experience with care-

givers (whether they serve as a reliable

secure base for exploration and safe haven

under threat) strongly shapes individual dif-

ferences in adult love experiences. Thus, for

example, those who have had inconsistent

caregiving (those high on the anxious attach-

ment or preoccupied dimension) are much

more likely to experience intense passionate

love and more likely to experience intense

unrequited love, whereas those who expe-

rienced a consistent lack of security (those

high on the avoidance dimension) are espe-

cially unlikely to experience passionate love

in adulthood (Aron et al., 1998; Hendrick

& Hendrick, 1989). Some preliminary evi-

dence even suggests that the brain systems

engaged by passionate love may be moder-

ated by individual differences in attachment

style (Aron, Fisher et al., 2004).

Love as a Story

Sternberg (1998) suggested that loving rela-

tionships can be described accurately by the

people involved through narrative autobi-

ographies, often suggesting culturally proto-

typical “stories.” For example, the story of a

couple locked in constant struggle is com-

mon, as is the story of couples growing to

love each other over time. This approach

seems promising given the general tendency

for people to organize their world in narra-

tive form and there has been some prelimi-

nary research support for the model (Stern-

berg, Hojjat, & Barnes, 2001).

Evolutionary Approaches

Because courtship and mate choice are cen-

tral aspects of reproduction in higher ani-

mals, it seems plausible that the experiences,

behaviors, and neural underpinnings of pas-

sionate love might be strongly shaped by

evolution. Thus, as noted in the section on

the biology of romantic love, Fisher (1998)

proposed that the brain system for roman-

tic attraction evolved to motivate individuals

to select among potential mating partners,

prefer particular conspecifics, and focus their

courtship attention on these favored individ-

uals, thereby conserving precious courtship

and mating time and energy.

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608 the cambridge handbook of personal relationships

As also noted earlier, another important

line of evolutionary thinking, largely based

on parental investment theory (Trivers,

1972), has emphasized gender differences

in what features are desirable in a mate

and in the basis for jealousy (eg, Buss

& Schmitt, 1993). There have also been

some approaches to the evolutionary basis

of experience and behavior in romantic love

arguing that the mating system exploits an

evolved bonding module between infants

and parent (Hazan & Diamond, 2000; Miller

& Fishkin, 1997).

Self-Expansion Model

Aron and Aron’s (1986) self-expansion

model posits (a) a primary human motiva-

tion to expand one’s self in terms of poten-

tial to attain desired goals and (b) that a

main way that people seek to expand their

self is in terms of “including others in the

self” through close relationships so that the

other’s resources, perspectives, and identi-

ties are treated to some extent as one’s

own. Both principles have received consider-

able research support (for reviews, see Aron

et al., 2001; Aron, Mashek, & Aron, 2004).

In terms of romantic love, Aron et al.(2000)

argued that the exhilaration and intense

focused attention of passionate love arises

from the rapid rate of including the other in

the self often associated with forming a new

romantic relationship. We have cited sev-

eral relevant studies throughout this chapter.

Companionate love, they argued, arises from

the ongoing expansion offered by the part-

ner and the potential for loss to the self of los-

ing the partner.(For example, Lewandowski,

Aron, Bassis, & Kunak,[2005] found that

the degree of negative impact on the self-

concept following relationship dissolution

was predicted by degree of ongoing self-

expansion that had been provided by the dis-

solved relationship.)

Summary and Conclusions

Romantic love is a nearly universal phe-

nomenon that has been the subject of schol-

arly interest for centuries but has only in the

last half century been a topic of systematic

scientific study. What has been learned from

this study is that romantic love is understood

by ordinary people in terms of its resem-

blance to a standard prototype and is best

understood by researchers for purposes of

systematic analysis in terms of various types

of love, most centrally in terms of a distinc-

tion between passionate and companionate

love. There has been considerable recent

progress in identifying the biological under-

pinnings of romantic love, including support

from animal data and human neuroimaging

studies for passionate love being linked with

dopamine-based reward processes, whereas

companionate love seems linked with bond-

ing more generally and perhaps specifically

with central oxytocin and vasopressin sys-

tems. The course of romantic love has been

well delineated in terms of predictors of ini-

tial romantic attraction and diverse stud-

ies providing insights and suggested direc-

tions for future research regarding the effects

of falling in love on the self, the processes

and motivations associated with unrequited

love, and the course of passionate love over

time including potential moderators of that

course. Finally, there are now at least seven

major approaches to understanding roman-

tic love that have served as the basis for

much of the research on the topic. These

approaches include cultural models, emo-

tion models, attachment theory, love as sex,

evolutionary theory, love as a story, and the

self-expansion model.

We hope that this review has conveyed

our view that the study of romantic love

is both important and a thriving scientific

endeavor, offering both a solid foundation

and vast opportunities for significant fu-

ture work.

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CHAPTER 33

Commitment

Caryl E. Rusbult

Michael K. Coolsen

Jeffrey L. Kirchner

Jennifer A. Clarke

The past 3 decades have witnessed dramatic

growth in relationships science. Much of this

work has sought to identify the determinants

and consequences of positive affect–attrac-

tion, satisfaction, or love. For example, the

goal of many studies is to explain the causes

of attraction or love; measures of satisfaction

frequently are employed as indices of cou-

ple well-being (for reviews, see Berscheid &

Regan, 2005; Berscheid & Reis, 1998). The

implicit or explicit assumption of this work

is that if partners love each other and feel

happy with their relationship, they should

be more likely to remain involved with one

another. In many respects, this point of view

makes good sense: All things considered, it

is easier to stick with a happy relationship

than a miserable one.

Unfortunately, this conventional focus

on the study of affective reactions fails to

address three key questions: First, why do

some relationships persist despite dissatis-

faction–for example, why do unhappy part-

ners sometimes remain together due to iner-

tia or “for the sake of the children”? Second,

why do some satisfying relationships end–

why do people sometimes abandon rela-

tively happy relationships to pursue desir-

able alternative partners? Third, how can we

account for persistence in the face of ordi-

nary fluctuations in affect? Given that satis-

faction ebbs and flows even in the most grat-

ifying involvements, and given that tempting

alternatives threaten even the most smitten

partners, why do some relationships endure

and thrive whereas others do not?

Over the course of the past 3 decades,

questions such as these have inspired some

social scientists to dedicate themselves to the

study of commitment. Scientists working in

this tradition believe that if we are to com-

prehend fully phenomena such as benev-

olent versus malevolent behavior, positive

versus negative motivation, and tenacious

persistence versus severance, understanding

commitment may be as important as–per-

haps more important than–understand-

ing positive affect. The goal of this chap-

ter is to review work in this tradition. We

begin by describing several formal models of

the causes of commitment. Next, we review

empirical work that is relevant to assessing

the validity of these models, discussing crit-

ical research findings and their implications

615

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616 the cambridge handbook of personal relationships

for each model. Then we describe several

important commitment processes, examin-

ing the generalizability of commitment phe-

nomena, the role of commitment in inducing

prosocial maintenance behaviors, the asso-

ciation of commitment with trust, and the

phenomenon of deteriorating commitment.

The chapter concludes with a review of con-

temporary trends in the commitment litera-

ture and suggestions for future research.

Formal Models of Commitment

dedicating unwarranted time or effort to an

activity, increasing commitment to a los-

ing enterprise, entrapment in escalating con-

flicts, and the manner in which investments,

side bets, and sunk costs may induce perse-

verance at a line of action (eg, Becker, 1960;

Blau, 1967; Brockner, Shaw, & Rubin, 1979;

Kiesler, 1971; Staw, 1976; Teger, 1980; Trop-

per, 1972). Thus, at the time during which

Levinger, Rusbult, and Johnson advanced

their theories of commitment processes, the

theme of unjustified persistence was promi-

nent throughout the social sciences. 1