Rayner Tai - Empirical Report Complete

Running Head: EXAMINING PARENTAL SEX DIFFERENCES IN MATE PREFERENCES 1
Examining gender differences in preferred characteristics for a potential son or daughter in law.
Rayner (Cheng Yang) Tai
Name: Rayner (Cheng Yang) Tai
Student Number: 900220179
Word Count: 4999
Supervisor: Greg Tooley and Christopher Cott
Campus: Deakin University Burwood
I, the undersigned, declare that this Empirical Report is less than the specified word limit, and that it
comprises original work and writing by me, and that due acknowledgement has been made to all other
material used.
Signed: Rayner (Cheng Yang) Tai Dated: 27/10/13

EXAMINING PARENTAL SEX DIFFERENCES IN MATE PREFERENCES 2
Abstract
Despite the vast amount of literature available on gender differences in the preferred
characteristics of mates, there is a lack of consensus on the factors that underpin them. Proponents of
evolutionary theory posit that these differences are the result of psychological mechanisms designed
to increase the genetic fitness of an individual and their relatives. Social role theorists in contrast,
suggest that these differences are due to the assignments of men and women into social roles, and that
mate preferences are the result of each gender trying to share the success of the other. The difficulty in
determining which theory best explains these differences is that both theories share similar
predictions. This study involved the use of an eye-tracker in examining the differences in mate
preference that parents have for a potential son or daughter in law as a way to obtain and test different
predictions from each theory. The study comprised of 101 participants, who were shown a series of
profiles of individuals, with each profile containing information about their physical attractiveness
and their resource-related traits, as well as traits such as family values and personality. As an indicator
of the relative importance of traits, their eye movements were tracked to record the amount of time
they spent fixated on each characteristic. As predicted, based on evolutionary theory mothers of
daughters spent longer looking at resource-related traits than fathers of daughters and parents of sons.
Also, fathers of sons spent more time fixated on physical attractiveness than mothers of sons and
parents of daughters. The results of this study suggest that evolutionary theory, rather than social role
theory accounts for the differences in mate preference found in humans.

Examining gender differences in preferred characteristics for a potential son or daughter in law.
The field of evolutionary psychology (EP) is a highly contentious area in modern-day
psychology (Buss, 1995). EP proposes an evolutionary basis behind the psychological mechanisms
that influence our thoughts and feelings (Michalski & Shackelford, 2010). EP suggests that human
behaviour is the result of psychological adaptations to recurrent issues in the environment from which
we evolved (Bereczkei, Voros, Gal, & Bernath, 1997; Emlen & Oring, 1977) These adaptations rely
on the evolutionary principles of natural selection and sexual selection (Buss, 1989b; Trivers, 1972).
An area that evolutionary psychology is concerned with is why there are such marked gender
differences in the preferred characteristics of potential partners. There is much debate as to the cause
of these differences, with many studies having been conducted in this area. Few studies however,
have examined the differences in characteristics that parents prefer. This report will explore the
different mate preferences in humans, as well as the competing theories behind these differences.
Principles of Evolution
Natural selection refers to the process in which generational changes occur in the traits of
organisms (Darwin & Bynum, 2009). Over many generations, advantageous traits will become
dominant in a population, however small the benefit. In this fashion, the natural environment of an
individual selects for traits that are advantageous to its survival and reproduction (Fisher, 1999;
Trivers & Willard, 1973).
Sexual selection, on the other hand describes the way that some individuals out-reproduce
others because they are better at acquiring mates, leading to the evolution of traits that are selected
specifically for their role in mating (Fisher, 1999). It is characterised by (a) competition within one
sex for members of the opposite sex, and (b) each gender preferring some characteristics in the
opposite gender over others (Trivers, 1972). Consequently, sexual selection has encouraged the
evolution of traits and characteristics with reproductive benefits, rather than purely for survival
(Feingold, 1990).
Mating Preferences
In humans, it has been noted that there is a remarkable consistency across cultures in the way
males and females differ in their preferred characteristics of potential mates (Buss, 1992; Schwarz &
Hassebrauck, 2012). Many studies have supported this notion, finding that while traits such as
intelligence, personality, and family values tend to be equally valued by both genders (Bereczkei,
2000), women have a tendency to prefer partners with resource acquisition capability and good
financial prospects (Feingold, 1992; Townsend & Levy, 1990). Buss (1989a) examined these
preferences across 37 different cultures. The results of his study showed that in most cultures women
valued the earning capacity and ambition of a mate more so than men did.

This was also supported in Buss’s (1988) earlier study on tactics used in mate attraction,
finding that males more frequently demonstrated tactics relating to the acquisition and display of
resources than females. Buss contended that these tactics correspond to the gender differences found
in mate selection, that females prefer mates who have high resources and earning capability. It has
been theorised that males with resources, shown by having good financial prospects are valued
because it indicates an ability to provide resources such as food and shelter for any potential offspring
(Schwarz & Hassebrauck, 2012; Trivers, 1972). Buss (1989a) proposed that this would provide a
female with an immediate material advantage, thereby increasing the fitness of her and her offspring
through the newly acquired economic benefits.
In contrast, a female’s reproductive capacity is shown to be related to her age, health and
physical appearance, with males using these cues to select fertile females for mating (Bereczkei et al.,
1997; Sprecher, Sullivan, & Hatfield, 1994). Accordingly, a number of studies have demonstrated that
males show a preference for females who are young and physically attractive (Townsend & Levy,
1990). Physical attractiveness in females has typically been characterised as having a symmetrical
face, theorised to signal good genes, and an ideal waist to hip ratio, an indicator for fertility and ideal
levels of oestrogen (Fink & Penton-Voak, 2002; Williams, 2001). This has been demonstrated by
Feingold’s (1990) meta-analysis on mate selection. Feingold found that men valued physical
attractiveness in potential mates higher than women did. Similarly, Buss (1989a) in his
aforementioned study also found that males overwhelmingly valued physical attractiveness and youth
more than women did. Buss noted that females tended to be more fertile, and at their reproductive
peak in their 20s. Age, is therefore a powerful indicator of a woman’s fertility.
Inclusive Fitness and Kinship Investment
The evolutionary theory behind parental mate selection relies on the concept of inclusive
fitness, which refers to adaptations that increase the likelihood of passing genes onto the next
generation (Queller, 1992). Inclusive fitness entails that an individual’s fitness is subject to not only
their own reproductive success, but the success of their genetic kin (Buss, 2008; Hamilton, 1963).
Generally speaking, an individual is related to their parents and siblings by 50 percent, they
are related to their grandparents and grandchildren by 25 percent, along with any of their parent’s and
sibling’s offspring (Queller, 1992). This ties in with Hamilton’s rule which states that with all else
being equal, natural selection favours mechanisms that give precedence to relatives (Hamilton, 1963).
Simply put, if more unique genetic material would be retained than what would be lost by an
individual’s sacrifice, be it resources or even its own life, natural selection would favour altruism
towards relatives (Nowak, 2006; West, Pen, & Griffin, 2002). This vested interest in passing on
unique genetic material is especially manifested in the level of parental care humans have for their

offspring. As the act of reproduction is so costly, it makes sense that there is inherent choosiness in
not only one’s selection of mates, but the mates of an individual’s children (Buss, 2008).
Having considered that, it is apparent in the provision of resources, altruistic acts and close
feelings, that grandparents are highly invested in their grandchildren. They share half the genetic
material that parents share, but are still highly influential in the success of a grandchild (Lahdenpera,
Lummaa, Helle, Tremblay, & Russell, 2004; Sear, Mace, & McGregor, 2000). By imparting
knowledge and experience, contributing to childcare, and assisting in resource acquisition; they
significantly increase their grandchild’s chance of survival (Hawkes, 2004; Lahdenpera et al., 2004).
Parental influence on the mating decisions of offspring
It is clear why grandparents would seek to influence the success of their grandchildren, to
allow the successful propagation of their genes. Studies have suggested that this influence is not
solely restricted to after their grandchild is born (Apostolou, 2009; Buunk, Park, & Dubbs, 2008). By
influencing their children’s partner choices, they potentially influence the manner in which their genes
are expressed and propagated.
Research into this area has consistently shown that mate selection is often manipulated by
social influences, particularly from an individual’s family (Sussman, 1953). Barber (1994) for
example, in his study addressing parent-adolescent conflict reported that conflict over mate choice
was among the most common causes for disputes between parents and children. It is clear that parents
have significant influence on their children’s mate choices, however little research has been
conducted on the traits that parents value when assessing a potential mate for their son or daughter.
While this concept of evolved parental preference has yet to be explored in detail, it is
reasonable to expect that parents may share similar preferences in a potential mate for their child, as
any grandchild produced would share a quarter of their genes (Apostolou, 2009). Accordingly, using
the principles of evolutionary theory, it would be expected that parents should prefer a young,
attractive and fertile female for their son. Likewise, one would predict that parents should prefer an
ambitious mate with good financial prospects for their daughter (Buss, 1992).
An alternative to the evolutionary perspective
This evolutionary perspective on mate preference however, has not been universally
recognised (Archer, 1996). An alternative is the social role theory (SRT), which posits that the
differences in men and women originate from the traditional assignments of men and women into
different social roles (Eagly, Wood, & Diekman, 2000). SRT suggests that the division of labour
between genders in society causes sex-differentiated behaviour and that these differences result from
the roles that individuals internalise from their society (Eagley & Wood, 1999).

In most societies, family systems are based on males being the resource provider and females
the domestic worker (Eagley & Wood, 1999). SRT maintains that it is these different responsibilities
and obligations, not a genetic adaptation that govern mate selection preferences. A consequence of
this is that women tend to seek successful and ambitious men as mates, in order to share their
economic success. Women may also prefer older men, as they are more likely to be established and
have resources accumulated (Eagly et al., 2000). On the other hand, men who obtain partners with
good homemaking capability, will increase the likelihood of being successful from a domestic
standpoint (Johannesen-Schmidt & Eagly, 2002).
Kasser and Sharma (1999) also found support for this, finding that in male dominated
cultures, where females have limited reproductive freedom and education inequality, females have
greater preference for ambition, socioeconomic status and financial resources. Conversely, in cultures
that did support female equality, this preference was not as strong. Kasser and Sharma suggested as
females gain more reproductive freedom, coupled with increases in career and education prospects,
their mate preferences will change, suggesting a social rather than genetic origin of these preferences.
The evidence supporting SRT however has been deemed to be inadequate (Buss, 1989b;
Townsend, 1989). Based on SRT, it would be expected that the sex which earns more would place
less importance on a mate’s earning capacity, and regard physical attractiveness as being more
important, in turn these preferences would be reversed for the sex which earned less. The results of
Wiederman and Allgeier’s (1992) study showed the opposite, finding that the more income a woman
was expected to earn, the greater the value they placed on the earning capacity of a potential partner,
contradicting SRT predictions. These results have also been supported by Townsend (1989) and
Archer (1996), with Archer concluding that evolutionary theory accounts for overall sex differences
considerably better than SRT. Wiederman and Allgeier (1992), noted however, that their findings
were by no means definitive, leading to Eagly and Wood (2000) stressing the need to examine SRT
using a variety of methods as well as cross-cultural perspectives.
The present study
Given the nature of the evidence presented above, it is clear that the evolutionary position in
mate selection preferences is strong. SRT on the other hand, does not share this widespread support,
but has still yet to be refuted. It is argued that this lack of consensus is because in the majority of
cases, the competing theories share the same predictions, with men still usually responsible for
providing resources, and women playing the role of the homemaker.
One area in which differences could be found is in parental investment into mate selection for
their offspring. Given that parents have a vested interest in their grandchildren, the present study
proposes that examining what characteristics parents value for their daughter or son, will enable the
competing theories to make different predictions. While evolutionary theory might predict that parents

may demonstrate similar preferred characteristics in a potential son or daughter in law as their same
sex child but not of their child of the opposite sex, SRT predicts that parents would change their
preferences to reflect the social role associated with the gender of their child, rather than their own
gender.
This study also proposes the use of an eye-tracker, rather than the traditional questionnaire
format utilised in other studies. Eye-tracking has been used successfully in similar studies (Seidman &
Miller, 2013). Employing a method such as this would also remove the issue with self-report
measures and limit any social desirability bias that may occur (Bong, 1996). On the basis of that, it
would be reasonable to assume that the length of time spent looking at a characteristic is an indicator
of the value of that characteristic to an individual. This study proposes that by creating a profile of an
individual, along with information about their financial prospects, ambition and a photograph of said
individual to represent attractiveness; measuring the time that a participant spent examining each
characteristic, would allow us to assess the importance of each trait to the participant.
Therefore, based on evolutionary theory it is expected that mothers would identify more with
their daughter, thus spending more time looking at resource-related traits in a potential son-in-law
more than fathers of daughters and parents of sons. It is also expected that fathers of sons would spend
more time looking at the photograph (physical attractiveness) of a daughter-in-law more so than
mothers of sons and parents of daughters. On the other hand, SRT would predict that parents would be
able to switch gender roles, and mirror the gender-related preferences of their child, with mothers and
fathers of sons not differing significantly in time spent looking at the photograph, while mothers and
fathers of daughters would not have a significant difference in time spent looking at resource related
traits. As these traits are not innate, parents would place greater importance on the characteristics that
are most relevant to their child.
Method
Participants
A total of 117 participants were recruited, with 16 participants excluded due to not
completing the required amount of trials. The remaining participants consisted of 101 parents of
young adults aged between 15 to 35 years old. There were 60 females consisting of 30 mothers of
daughters (M = 49.37, SD = 6.46) and 30 mothers of sons (M = 49.07, SD = 7.27). For males there
was a total of 41 participants with 22 fathers of daughters (M = 50.41, SD = 8.53) and 19 fathers of
sons (M = 53.16, SD = 5.63). The participants came from a wide range of cultural backgrounds, and
were recruited using advertisements and flyers targeted towards the parents of students at Deakin
University Burwood. All participants were naïve to the purpose of the experiment.

Materials
Firstly, a pilot study consisting of an online questionnaire was conducted. The questionnaire
contained 150 photographs of females and 132 of males acquired from the Shutterstock website
(www.shutterstock.com). Participants were required to rate each photograph on a scale ranging from 0
(not attractive) to 10 (very attractive). There were 48 raters for the pilot study. The 15 highest rated,
15 lowest rated, and the 15 median photographs were used to form the stimuli for the main study.
For the main study, participants were presented with a plain language statement and consent
form, and asked to complete a demographic survey prior to partaking in the study (refer to Appendix
B). A Tobii T120 eye-tracking computer (120 Hz sampling rate) was used to track the eye movements
of participants when they were presented with the stimuli. The T120 has been shown to have high
reliability and accuracy (Lenzner, Kaczmirek, & Galesic, 2011). Furthermore, eye trackers have been
used successfully in previous research examining gender differences in time spent looking at the
physical attractiveness of an individual (Seidman & Miller, 2013).
The stimuli consisted of 29 pairs of randomly allocated same-sex profiles of an individual.
Each profile included a photograph of an individual, along with a shaded 3-point Likert scale of the
individual’s earning potential, ambition, generosity, intelligence, family orientation and sociability
(Refer to Appendix C for examples). The characteristics of interest in this study were resources and
physical attractiveness, as preference for these traits tends to differ significantly between genders
(Buss, 1989a). Resources was represented by the amount of time spent looking at ambition and
earning potential, while the physical attractiveness of an individual was represented by the
photograph. The four remaining characteristics, while important in mate selection, were ones that did
not tend to differ significantly between genders, and were used as distractor variables (Buss, 1989a;
Moore, Cassidy, & Perrett, 2010).
Design
A between subjects experimental design was used. There was one independent variable: the
gender of the parent and their child, i.e., mothers of daughters (MOD), mothers of sons (MOS),
fathers of daughters (FOD) and fathers of sons (FOS). There were two dependent variables: time
spent looking at resource related traits (earning potential and ambition), and time spent looking at the
photograph (representing physical attractiveness).
Procedure
Approval to conduct the study was obtained from the Deakin University Ethics Advisory
Group (HEAG), refer to Appendix A. The study was conducted at Cognitive and Exercise
Neuroscience Laboratory (CENU) at Deakin University Burwood campus. Participants first received
a plain language statement and completed the consent form along with a demographic survey.

Participants were then positioned in front of the T120 eye-tracker with their eyes positioned
approximately 60cm away from the computer screen. The participant’s eye movements were then
assessed for compatibility with the T120, the eye tracker was then calibrated to each participant. An
example of how the stimuli would present itself was shown to participant prior to commencement of
the experimental phase.
Participants were then presented with 29 trials featuring pairs of stimuli, each pair was shown
on the screen for 10 seconds. At the end of each trial, participants were required to select which
individual they would prefer as a partner for their child based on the characteristics shown.
Participants were allowed to take as much time as they needed during this selection phase. The first
three pairs shown were used as dummy trials, to allow the participant to familiarise themselves with
the process. If the time spent fixated on the screen was less than 8 seconds for any given trial, i.e.,
participant looks away from the screen, that trial was removed from the data. If a participant
completed fewer than 75% of all trials, they were also excluded from the analysis. The data collected,
recorded the amount of time in milliseconds each participant spent looking at each trait of a potential
son or daughter in law.
Results
Prior to analysis, the data was screened for outliers and checked to ensure assumptions were
met as per Tabachnick and Fidell (2013). A total of 16 cases were deleted due to missing data. The
data for one of the variables (physical attractiveness) was found to be slightly skewed. However due
to the integral nature of physical attractiveness to the study, along with the robust nature of ANOVAs
(Analysis of Variance), and that all other assumptions were met, the decision was made to keep this
variable and use a one way ANOVA. Data was analysed using IBM SPSS Statistics for Windows 21.
Means, standard deviations and confidence interval statistics are presented in Table 1.
An inspection of the means revealed that FOS spent the most time looking at the physical
attractiveness of a potential son or daughter in law, followed by FOD, MOS, and MOD. This trend
can be seen in Figure 1. A one-way between subjects ANOVA was conducted to compare the effect
of parent child gender on time spent looking at physical attractiveness. A Bonferroni adjusted alpha
level of .025 per test (0.5/2) as per Tabachnick and Fidell (2013) indicated that there was a significant
main effect of parent-child gender on the amount of time spent looking at the photograph, F(1,97) =
7.11, η2
= 0.18, p < .001. As shown in Table 2, post-hoc comparisons using the Tukey HSD test at a
significance level of p < .05 indicated that FOS spent significantly longer looking at the photograph
than MOD, and MOS. These effect sizes were found to be large (Cohen, 1988). There were also
differences between MOS and MOD, with a small effect size found, and between FOS and FOD, with
a large effect size, however these were found to be not significant.

An inspection of the means revealed that MOD spent the most time looking at the resource-
related traits of a potential son or daughter in law, followed by MOS, FOD, and FOS. This trend can
be seen in Figure 2. Another one-way between subjects ANOVA was then conducted. A Bonferroni
adjusted alpha level of .025 per test (0.5/2) found that there was a significant main effect of parent-
child gender on time spent looking at resource related traits, F(1,97) = 8.364, η2
= 0.20, p < .001. As
shown in Table 2, post-hoc comparisons using the Tukey HSD test at a significance level of p < .05
indicate that MOD spent significantly longer looking than FOD, with a large effect size, and FOS,
with a very large effect size. The remaining comparisons also found differences but these were not
significant, with FOD looking more than FOS and MOD more than MOS. These comparisons had
moderate effect sizes.
Table 1
Descriptive statistics for the amount of time (ms) spent looking at photograph and resource related traits of a potential son
or daughter-in-law for MOD, MOS, FOD and FOS.
95% Confidence Intervals
for Mean
N Mean SD Lower Upper
MOD 30 2183.58 1034.32 1797.36 2569.81
Photograph MOS 30 2577.76 1278.33 2100.42 3055.10
FOD 22 2879.93 1305.12 2301.27 3458.59
FOS 19 3827.20 1403.81 3150.58 4503.81
MOD 30 2234.91 552.41 2028.64 2441.19
Resources MOS 30 1974.22 518.72 1780.53 2167.91
FOD 22 1812.76 462.70 1607.61 2017.91
FOS 19 1501.85 499.46 1261.12 1742.58
Table 2
Results of post-hoc comparisons using the Tukey HSD test.
Mean Difference Significance
Level
Cohen’s d
FOS-MOD 1643.61 p < .001* 1.33
Photograph FOS-MOS 1249.44 p = .01* 0.93
FOS-FOD 947.27 p = .08 0.70
MOS-MOD 394.17 p = .61 0.34
MOD-FOD 422.15 p = .02* 0.83
Resources MOD-FOS 733.06 p < .001* 1.39
MOD-MOS 260.70 p = .21 0.49
FOD-FOS 310.91 p = .22 0.64
Note. *All significant values reported at p < .05

Figure 1: Time spent looking at the physical attractiveness (photograph) of a potential son or daughter-in-law in
milliseconds for MOD, MOS, FOD and FOS.
Figure 2: Time spent looking at the resource related traits of a potential son or daughter-in-law in milliseconds for MOD,
MOS, FOD and FOS
2000
2200
2400
2600
2800
3000
3200
3400
3600
3800
4000
MOD MOS FOD FOS
Timespentlookingatphotograph(ms)
Parent-Child Gender Type
1400
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1700
1800
1900
2000
2100
2200
2300
MOD MOS FOD FOS
Timespentlookingatresource-relatedtraits(ms)
Parent-Child Gender Type

Discussion
The aim of this study was to examine evolutionary theory and SRT to determine which theory
serves to better explain the marked gender differences in mate preferences found in humans. By
examining parents and how much time they spent looking at specific characteristics in a potential
partner for their child, this enables the competing theories to have differing predictions. If the
evolutionary theory behind mate selection is valid, we would expect that FOS would spend
significantly more time looking at the photograph than MOS, while mothers would spend
significantly more time looking at resource related traits than fathers. SRT, on the other hand, would
predict that MOS and FOS would not differ significantly in time spent looking at the photograph,
while FOD and MOD would not have a significant difference in time spent looking at resource related
traits.
The results of this study did not support SRT, as MOD and FOD differed on the amount of
time spent looking at resource-related traits, while MOS and FOS differed on the amount of time
spent looking at the photograph. The findings were consistent with those expected if evolutionary
theory was correct. For physical attractiveness, FOS spent significantly more time looking than
mothers, suggesting that they exhibited greater preference for the physical attractiveness of a potential
daughter-in-law. This outcome suggests that mothers are unable to switch social roles to match that of
their sons, with there being no adjustment in mate selection preference. This difference is consistent
with the marked gender differences found in the literature (Buss, 1989b). As it is evolutionarily
advantageous for females to prefer resource-related traits over physical attractiveness in a partner, in
line with the evolutionary theory of mate selection preferences, mothers were less concerned with the
physical attractiveness of a potential son or daughter-in-law than fathers (Schwarz & Hassebrauck,
2012). In addition to this, the comparison between fathers found that FOS looked more than FOD, but
this difference fell just short of significance. However given the large effect size found for this
comparison, and the marked trend shown in Figure 1, an argument could be made that if the sample
size was larger, this comparison could have reached significance. A significant result would suggest
that FOS are able to empathise with their son’s tendency to prefer physical attractiveness, while FOD
are not as concerned, given that females tend to prefer resource-related traits more so than physical
attractiveness (Buss, 1992).
For resources on the other hand, MOD spent significantly more time looking than fathers,
again indicating a greater preference for the resource-related traits of a potential son-in-law. This
finding suggests that fathers are unable to switch social roles to match that of their daughters, this
adjustment being a key component of SRT. It is theorised that this is because males tend to prefer
physical attractiveness more so than resources in a potential mate, therefore in terms of parental
investment, fathers are not as interested in the resource-related traits of a son or daughter-in-law as a
mother would be. The comparisons for mothers found that MOD spent longer looking than MOS.

This difference failed to reach significance; however upon examining the trend shown in Figure 2, it
is likely that with a larger sample size this may have been significant. In this case, a significant result
would indicate that MOD identify more with their daughter’s tendency to prefer resource-related
traits, while MOS are not as concerned, as males tend to prefer physical attractiveness more than
resource-related traits in a potential partner (Fink & Penton-Voak, 2002; Townsend & Levy, 1990).
The results from this study are also consistent with a trend found in kin selection theory called
paternal uncertainty. Due to the nature of human reproductive processes, males can never be
completely certain that a child is theirs due to possibility of female infidelity, while females can have
this certainty because they actually carry the child (Bishop, Meyer, Schmidt, & Gray, 2009). For
paternal grandfathers, this degree of uncertainty is expressed twice for their son’s children. Maternal
grandmothers, on the other hand, can be completely certain that any of their daughter’s children are
their grandchildren (Buss, 1996). As this certainty of genetic relatedness varies for each grandparent,
it could be expected as per Hamilton’s rule that grandparents will have differing levels of investment
for their grandchildren, with maternal grandmothers being the most invested and paternal grandfathers
the least (Bishop et al., 2009; Chrastil, Getz, Euler, & Starks, 2006). Relating back to the study at
hand, this differing level of investment is shown quite clearly in the trend exhibited in Figure 2, with
MOD valuing the resource-related traits of a potential mate for their child the most, followed by
MOS, FOD, and lastly FOS. Given that females exhibit greater preference for mates with high
resource acquisition capability as it is beneficial for their offspring (Buss, 1989a), it could be argued
that interest in the resource-related traits of a potential son or daughter-in-law, as demonstrated by
time spent looking, is associated with the level of grandparental investment due to genetic relatedness.
What this study brings to the literature is the use of a novel measure in assessing preferred
characteristics. The use of an eye-tracker in this study, rather than a questionnaire or other self-report
measures limits issues surrounding social desirability that participants may have been subject to
(Bong, 1996; Randall & Fernandes, 1991). Instead of relying on the self-report of participants to
answer questions regarding their preferences, using an eye-tracker to record how long they spent
fixated on a particular characteristic is an observation of their subconscious behaviour, and therefore
less prone to such biases.
An assumption that this study makes is that the amount of time spent looking at a
characteristic translates directly to the importance of that characteristic to a participant. A case could
be made that participants may have made their decision on which individual to choose without taking
into account the information presented, and simply looked randomly at characteristics on the screen.
Moreover, that because participants did not explicitly state which characteristic was important to
them, time spent looking could be negligible in any decision they make. Studies on viewing time
however, have found that interest can be inferred by the amount of time spent looking (Kelly &

Teevan, 2003; Quinsey, Ketsetzis, Earls, & Karamanoukian, 1996). Taking that into account, as well
as because that participants were instructed to select a potential mate for their child based on the
information presented to them, and that the results were in line with previous studies on mate
preference, it is reasonable to assume that that the eye-tracking data collected was a relatively
objective measure of the characteristics that are important to them.
There were however, several limitations to the study. The profiles that participants were
shown consisted of an individual’s photograph, along with scales of that individual’s score on
particular characteristics. Given that humans have a tendency to fixate towards salient stimuli (Judd,
Ehinger, Durand, & Torralba, 2009), it is possible that participants may have spent more time looking
at the photograph simply because of how salient it was in comparison to the characteristic scales. In
addition to this, it should also be noted that the photograph also took up significantly more viewing
area than any of the scales, so not only were the photographs more visually striking, they were also
the largest stimuli displayed on the screen.
Following on from this, studies have shown that males are generally more interested and
responsive to visual stimuli than females (Hamann, Herman, Nolan, & Wallen, 2004; McGlone &
Kertesz, 1973). This tendency could have potentially explained the marked gender differences found
in the results of the study. Fathers may have looked longer than mothers because the photographs
were more visually appealing to them, rather than due to any evolutionary benefit their child may
obtain. However, given that the results were consistent with the literature, and that FOS looked longer
than FOD, this may not have impacted significantly on the study.
Future research could look into examining the choices that the participants made. Correlating
the choices that participants made in terms of a potential son- or daughter-in-law, with the time spent
looking at each characteristic would enable researchers to verify that time spent looking translated to
the importance of that characteristic. Other possible avenues could include ensuring that any stimuli
presented were consistent in size and saliency, to avoid a bias towards the photograph, as well as an
increased sample size (in the case of this study, more fathers were needed).
As mentioned above, in the majority of studies, evolutionary theory and SRT share similar
predictions. Given that this study was able to have different predictions for each of the theories, by
examining parental mate preference, as well as matching the trends predicted by Hamilton’s rule, the
results of this study contradict SRT, and lend support to the strong evolutionary basis for mate
selection preferences already existing in the literature. This study has also increased the body of
knowledge in EP, and adds to the understanding of what mechanisms govern the choices humans
make in selecting a potential mate. It has been over 150 years since Darwin coined the term natural
selection, much has been learned since then, however it is clear that there is still much more to
explore in the field of EP.

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Appendix A
To: Professor Greg Tooley
School of Psychology
From: Secretary – HEAG-H
Faculty of Health
CC: Chris Cott, Kathryn Richards, Brogan Nunn, Carina Purdea, Catherine Pepe,
Rayner Tai, Claire Nicolas, Georgia Kouselas
Date: 1 July, 2013
Re: HEAG-H 78_2013: A novel protocol for examining parent and child mate
preference
Approval has been given for Professor Greg Tooley, School of Psychology, to
undertake this project for a period of 1 year from 1 July, 2013. The current end
date for this project is 1 July 2014.
The approval given by the Deakin University HEAG - H is given only for the project and for the period
as stated in the approval. It is your responsibility to contact the Secretary immediately should any of
the following occur:
• Serious or unexpected adverse effects on the participants
• Any proposed changes in the protocol, including extensions of time
• Any events which might affect the continuing ethical acceptability of the
project
• The project is discontinued before the expected date of completion
• Modifications that have been requested by other Human Research Ethics
Committees
In addition you will be required to report on the progress of your project at least
once every year and at the conclusion of the project. Failure to report as
required will result in suspension of your approval to proceed with the project.
An Annual Project Report Form can be found at:
http://www.deakin.edu.au/hmnbs/research/ethics/ethicssubmissionprocess.php
This should be completed and returned to the Administrative Officer to the HEAG-H, Pro-Vice
Chancellor’s office, Faculty of Health, Burwood campus by Tuesday 19th November, 2013 and when

the project is completed. HEAG-H may need to audit this project as part of the requirements for
monitoring set out in the National Statement on Ethical Conduct in Human Research (2007).
Good luck with the project!
Steven Sawyer
Secretary
HEAG-H
Human Ethics Advisory Group, Faculty of Health,
Melbourne Burwood Campus, 221 Burwood Highway, Burwood, VIC 3125
Tel 03 9251 7174, email health-ethics@deakin.edu.au www.deakin.edu.au

Appendix B
Appendix B1
PLAIN LANGUAGE STATEMENT AND CONSENT FORM
TO: Participant
Plain Language Statement
Date: 13/03/13
Full Project Title: A novel protocol for examining parent and child mate preferences
Principal Researcher: Professor Greg Tooley, Dr Christopher Cott
Student Researcher: Kathryn Richards, Brogan Nunn, Carina Purdea, Catherine Pepe, Cheng
Tai, Claire Nicolas, Georgia Kouselas
Associate Researcher(s):
We invite you to take part in a project that aims to investigate potential differences
between parents and offspring in their views on what traits might be desirable in a long
term partner for the offspring. Evolutionary theory has hypothesized that males and females
will differ in their preferences in mate characteristics given a variety of factors and given
that children carry 50% of a parent’s genes, parents may also want their children to take
partners who carry these traits. In other words, do parents display the same preferences
they show when choosing a partner for themselves, when looking at potential partners for
their children?
In order to examine whether parents display gender differences in mate preferences for
their children, parents of young adults, as well as young adults themselves, have been
recruited for this study. During the study, you will view a series of pages on the computer,
each of which has a choice between two potential long term partners, either for yourself, or
if you are a parent, for your child. You will be able to view a variety of characteristics of each
of the potential partners, and you will then have to choose which partner you prefer.

However, in order to distinguish which characteristics are viewed as most important, we
have limited the time you have to look at the characteristics before you make your choice.
While you do this, you will be monitored by a special device that follows your eye-
movements. This device will give us further information about which items people looked at
first, how long people looked at a certain characteristic, and so on. We expect the task to
take 20-30 minutes to complete. The testing will take place at the Cognitive and Exercise
Neuroscience Unit (CENU) laboratory at the Burwood campus of Deakin University.
There are no foreseeable risks to participants for engaging in this research. However,
participants may benefit from participation by better understanding how and why they
make evaluations of people, especially in the context of relationships. Furthermore, the
wider community and especially the scientific community will benefit from further
understanding the mechanisms behind human behaviour in regards to mate-selection.
Your data will be deidentified upon completion, so once you have completed the study your
results will be completely anonymous. The results of the project will be used in theses
completed as a requirement for conferral of fourth-year university degrees. Results may
also be published in peer-reviewed scientific journals. However, any data that is published
will be completely anonymous so there will be no risk to participants’ privacy during any
stage of the research. Any participants interested in seeing the results of the study can view
the research output information of the principle researcher on the Deakin University
website.
The two principle researchers will be constantly monitoring the progress of the research,
and in the case of on-site participants, one or both of the principle researchers will attempt
to be present at all testing sessions. The project will be funded by students’ research
allocation budgets.
You may withdraw from the study at any time without risking any adverse effects. If your
data is still identifiable we will remove it from the study. However, if your data is already
anonymous we will be unable to do so. If you experience any distress as a result of
participating in the study, you may contact Deakin University’s counselling service from
Monday to Friday, 9am to 5pm on (03) 9244 6300.
If you have any queries, you may contact the researchers at:
Professor Greg Tooley
+61 3 925 17365
gregory.tooley@deakin.edu.au
Complaints
If you have any complaints about any aspect of the project, the way it is being conducted or
any questions about your rights as a research participant, then you may contact:

The Manager, Research Integrity, Deakin University, 221 Burwood Highway, Burwood
Victoria 3125, Telephone: 9251 7129, research-ethics@deakin.edu.au
Please quote project number [201X-XXX].

Appendix B2
TO: Participant
Consent Form
Date:
Full Project Title:
Reference Number:
I have read and I understand the attached Plain Language Statement.
I freely agree to participate in this project according to the conditions in the Plain Language
Statement.
I have been given a copy of the Plain Language Statement and Consent Form to keep.
The researcher has agreed not to reveal my identity and personal details, including where
information about this project is published, or presented in any public form.
Participant’s Name (printed) ……………………………………………………………………
Signature ……………………………………………………… Date …………………………

Appendix B3
TO: Participant
Withdrawal of Consent Form
(To be used for participants who wish to withdraw from the project)
Date:
Full Project Title:
Reference Number:
I hereby wish to WITHDRAW my consent to participate in the above research project and
understand that such withdrawal WILL NOT jeopardise my relationship with Deakin
University.
Participant’s Name (printed) …………………………………………………….
Signature ……………………………………………………………….Date ……………………
Please mail this form to:
Prof. Greg Tooley
School of Psychology
Deakin University
221 Burwood Highway
Burwood, VIC 3125

Appendix C
Appendix B3
Appendix B4

Appendix D

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