Transcript Infidelity - Psychlology Teaching Resources from

Many human societies are based around
notionally monogamous relationships
However, it is relatively common for both
men and women to engage in sexual
activity with additional partners
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Infidelity
Infidelity
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Sexual infidelity occurs in 20-25% of
marriages (Wiederman, 1997)
65-75% of university students have had some
degree of ‘extradyadic involvement’ whilst in a
‘serious’ relationship (Shackelford et al, 2000)
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Prevalence of sexual infidelity difficult to
measure for obvious reasons. Some
estimates from the US:
Infidelity
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It occurs in both males and females
E.G. in some supposedly monogamous bird
species 10-40% of chicks were fathered by a
male other than the female’s pair-bonded
mate
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Infidelity also occurs in various animal
species, including those that apparently
form monogamous pair bonds
Infidelity might have evolutionary
advantages & be an adaptive strategy
If so, male & female infidelity are likely to
have different motives & possible
consequences
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Infidelity & Evolution
Male Infidelity
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Men more likely to report having affairs that
were ‘just about sex’ (Glass & Wright, 1985)
Male infidelity not necessarily linked to
dissatisfaction with current relationship (Hall &
Fincham, 2005)
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Possibly explainable in terms of ‘quantity’
based indiscriminate mating strategy
More partners = more offspring
Female Infidelity
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Best physical specimens may not be best
resource providers (‘best of both worlds’)
Infidelity more strongly linked to
dissatisfaction with currently relationship than
in male infidelity (Glass & Wright, 1985)
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Possibly explainable in terms of ‘quality’
based strategy for optimising survival
chances of offspring
Infidelity
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M less likely to forgive, more likely to break up
with sexually, rather than emotionally
unfaithful partner (Shackelford et al, 2002)
F seem more sensitive than M to emotional
infidelity (Hall & Fincham, 2004)
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That infidelity serves different purposes in
M & F is supported by other evidence e.g.
Infidelity & Parental Investment
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It makes poor evolutionary sense to invest in
offspring that don’t carry your genes
Females can be certain that the young are
theirs, males less so
‘Mummy’s babies, daddy’s maybes’
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Infidelity may have an influence on
investment in offspring & other parental
behaviour
Infidelity & Parental Investment
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Anderson (2005) meta-analysis, studies of
general population: 3.9%
Bellis et al (2005) meta-analysis, studies of
general population: 3.7%
CSA (2005) cases of disputed paternity only:
16%
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Misattributed paternity prevalence is
difficult to measure. Sample estimates:
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Infidelity & Parental Investment
Infidelity & Parental Investment
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This tendency is multiplied across
generations, so mother’s mother (guaranteed
relationship) invests more than father’s father
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Because females can always be certain
that the offspring carry their genes they
are likely to invest more resources