Summary of:
Sagarin, B. J., Vaughn Becker, D., Guadagno, R. E., Nicastle, L.D., Millevoi, A. (2003).
Sex differences (and similarities) in jealous: The moderating influence of infidelity
experience and sexual orientation of the infidelity. Evolution and Human Behavior, 24,
17-23.
Summary By: Claire Greene, Emily Smith, Melissa Munoz, Courtney Perley
For Dr. Mills’ Psyc 310 class, Fall, 2009
Introduction
From an evolutionary perspective, male and female reproductive strategies are
different due to the opposing reproductive challenges they face. Males suffer from
paternity insecurity, in which they are uncertain as to whether or not the offspring they
father is biologically their own. Females, on the other hand, are maternally secure and
thus devote time and energy pre-conception to ensure that her mate has plentiful
resources to offer, and is committed both to her and her offspring. As the reproductive
challenge that males face is uncertainty that an offspring is genetically his, males risk
allotting resources to the offspring that will benefit the genetic success of another male.
Alternatively, females do not face this challenge and they are instead concerned with
having adequate resources so that her offspring, and in turn her genes, will be developed
and carried successfully into the future. Females typically depend on males for corporeal
resources, and males depend on females for genetic success. When reproductive success
is threatened, jealousy emerges and is manifested to different degrees in males and
females. Research has shown that men and women differ in their responses to emotional
and sexual infidelity. It has been found that women find emotional infidelity to be more
distressing than sexual infidelity, while men find the latter to be more distressing.
Typically, a forced-choice paradigm, in which subjects have been asked to choose
whether emotional or sexual infidelity would be more upsetting, has been used in past
research to examine these sex differences. This study elaborates on this method and
examines both the forced-choice paradigm and continuous measures to investigate
responses to jealousy and infidelity. The continuous measures focus on asking the
subjects to what degree emotional versus sexual infidelity upsets them. While jealousy is
rooted in the different reproductive challenges that males and females face it is predicted
that such differences will disappear when conception is not a possibility. As such, this
study examined the effect of introducing same-sex infidelity on levels of jealousy in
males and females.
Study 1
In the first study, 513 participants were randomly assigned to two conditions. The
initial condition evaluated opposite-sex infidelity by forcing subjects to imagine an
opposite-sex relationship and asking them to determine whether they felt emotional or
sexual infidelity would be more distressing. Next, they were asked to rate on a 10-point
scale, ranging from not at all jealous (0) to extremely jealous (9), how jealous they would
feel if their partner were to form a strong emotional attachment to this person, as well as
how jealous they would feel if their partner were to enjoy sexual intercourse with this
person. The same procedure was repeated for the second condition, except the
participants were asked to imagine a same-sex infidelity scenario. A significant sex
difference was found among participants considering the opposite-sex scenario, and
males reported more distress to sexual infidelity than to emotional infidelity, while the
opposite was found among females in this condition. There was no significant sex
difference among those considering a same-sex infidelity. Males also reported higher
levels of jealousy in response to sexual infidelity than females, while females reported
higher levels of jealousy in response to emotional infidelity rather than sexual infidelity
(see Figure 1).
Study 2
The procedure implemented in the second study was congruent to that in the first
study, however subjects were only given the scenario of an opposite-sex infidelity, as no
gender differences were found in response to same-sex infidelity in Study 1. Participants
were also asked whether or not they had ever been a perpetrator or a victim of infidelity.
The purpose of this added measure was to determine whether or not actual previous
involvement with infidelity, specifically being a victim of infidelity, would increase
levels of jealousy. Male victims of infidelity reported greater distress with regard to
sexual infidelity than those who hadn’t. Female perpetrators of infidelity reported more
distress to sexual infidelity than females who had never perpetrated infidelity.
Discussion
This study shows that sex differences in jealousy are robust and not only
manifested through the use of the forced-choice paradigm. These studies present
evidence for the moderating influence of infidelity experience on which type of jealousy
would be more distressing. Overall, these findings imply that sex differences in jealousy
are influenced by factors that affect reproductive success. Male jealousy should serve to
reduce the risk that female partners will copulate with rival males, while female jealousy
should serve to reduce the risk that male partners will invest resources in the offspring of
rival females. When threat to reproductive success is eliminated, as is the case in samesex infidelity, differences in male and female levels of jealousy and distress disappear
because conception is impossible.
Critique
Part A: Identify up to three points made by the author that the panel found
especially interesting or informative:
 The results of both surveys were the same, suggesting that the sex difference is
a robust effect and not merely an artifact of the forced-choice paradigm.
These results matched the theory that was stated in the introduction of the
article.
 A same-sex infidelity does not entail the asymmetrical threats of mistaken
paternity and of resources being diverted to another woman’s children,
suggesting both that the sexes may be similar in their jealous responses and
that such responses may be less intense than in the case of opposite-sex
infidelities. Both men and women reported significantly less intense jealousy
in response to a same-sex infidelity.
 For women, emotional infidelity elicited significantly more jealousy than
sexual infidelity. For men, sexual infidelity elicited marginally more jealousy
than emotional infidelity.
 Bisexual behavior is sufficiently well documented both historically and crossculturally to indicate that responding appropriately to same-sex infidelities is
a challenge with a long history. Also, same-sex sexual interactions are
sufficiently widespread in other animals, including other primates, to suggest
that responding differentially to the homosexual versus heterosexual
behavior of others is an ancient adaptive problem.
o
Since jealousy is a dangerous emotion, with potentially dire
ramifications for all concerned, it would be reproductively
advantageous to feel intense jealousy specifically when one’s
reproductive outcomes are at risk.
Part B: Identify up to three arguments made by the author that the panel either
disagreed with and/or for which you think the author made a weak case, or were
unclear, and explain why you came to that conclusion:
 For women, experience as a victim of infidelity did not serve as a moderator,
but experience as a perpetrator did. Women who reported cheating on a
past romantic partner were significantly more likely to indicate that a sexual
infidelity would cause greater distress compared to women who had not
cheated. While male victims of infidelity were significantly more likely than
male non-victims to report greater distress in response to a sexual infidelity.
o
We didn’t understand why women who had cheated would have a
greater distress that they would fall victim of infidelity by their
partners more than women who hadn’t cheated
o
Its seems like women who have cheated wouldn’t care as much if
their partner cheated on them too
 Both studies were performed on undergraduate students, so there isn’t a wide
range of people surveyed at different ages and you can’t make a
generalization based on that data
o
We thought that surveying males and females of all different ages
would give more accurate data about where jealousy stems from in
males and females when it comes to infidelity.
o
Only testing males and females between the age of 18-22 doesn’t
allow one to generalize the results for the whole population
o
Survey wasn’t given based on random selection, it was only given to
students in introductory psychology classes
Outline
I) Evolutionary history of jealousy
A) Each sex had different threats to their reproductive fitness
1) Males had no paternity assurance
2) Females had to make sure the potential mate would commit his resources to
her children
B) Responding differently to the homosexual versus heterosexual behavior of
potential mates is rooted in evolutionary history
1) Bisexual behavior is well documented in human history on a global scale
2) Examples of same-sex sexual interactions across different animals such as
primates
C) Jealousy is an advantageous emotion in regards to protecting an individual’s
reproductive outcome that is at risk
II) The type of infidelity predicts which sex will feel threatened
A) Sexual infidelity
1) Males will have greater distress
B) Emotional infidelity
1) Females will have greater distress
III) Infidelity involving the opposite sex versus the same sex has different effects on
jealousy.
A) Opposite-sex partners
1) Both sexes show more jealousy when their partner commits opposite-sex
infidelity
B) Same-sex partners
1) Both sexes show less jealousy when their partner commits same-sex infidelity
(a) No threat of conception or resource loss
IV) Previous victimization to cheating predicts degree of jealousy on future experiences
A) Males who were past victims of an infidelity are more likely than non-victims to
report more distress over sexual infidelity
B) Females showed two different effects
1) Experience as a victim of infidelity did not serve as a moderator
2) Experience as a cheater predicts that the would have more distress of sexual
infidelity compared to non-cheaters
Test Questions
1. Women and men fact different challenges to their reproductive fitness. True or false?
2. It is reproductively advantageous to feel jealous when one’s reproductive outcomes
are at risk. True or false?
3. For both sexes, it is not important whether one’s mate commits infidelity with the
same or opposite sex. True or false?
4. Males are more likely to feel jealous about:
a. Sexual infidelity
b. Emotional infidelity
5. If a woman was a cheater in the past then she will feel _________ distressed about
sexual infidelity.
a. Less
b. More
6. Women would be jealous about their mate’s mistress because:
a. Their resources are being threatened
b. Their maternal assurance is being threatened
Answer Key:
1. True
2. False
3. False
4. A
5. B
6. A
Figure 1