Study 2 - Asch (1955)



Buss (1989)

Sex differences in human mate preferences

Field of psychology: Individual Differences

1. CONTEXT AND AIMS

Context

You have to pick one of the following to marry. Who do you pick? Why?

If we accept that human behaviour has evolved, characteristics, behaviour or genes that increase the success of reproduction should appear more often in the general population. Thornhill & Thornhill (1983) propose that individuals lacking preferred characteristics will not be selected to mate and therefore will not be able to become people’s ancestors. This is why current mate preference is of interest to evolutionary psychologists because they reflect prior selection pressures, thus allowing us to learn about humans’ past reproductive history. They also demonstrate the current direction of sexual selection by showing us who is likely to be selected as a mate.

Despite the importance of mate preferences, little is known about which characteristics are valued by human males and females. There are three possible arguments that predict particular sex differences in mate preferences.

1. Prediction based on parental investment and sexual selection theory (Trivers, 1972): This theory states that sexual selection is driven in part by the different levels of investment males and females make in their offspring. Biologically, in mammals, male investment is minimal, whereas the female investment is much greater. The female has to carry the child, and also has to produce milk to feed the child, as well as generally care for and look after it, all of which require a great deal of the female’s biological resources as well as physical resources and time.

• Prediction: If we follow this through, we would predict that women are likely to be choosier when selecting a mate. In particular, they may choose a partner who can offer resources (food, territory, and protection). This will enhance the female’s reproductive success, as any child she bears will have a greater chance of survival (and consequently, passing these genes on).

• In modern times, this need for resources might not necessarily be food and shelter, but might be translated into money and status, and men with ambition and industriousness.

2. Prediction based on reproductive value (Symons, 1979) and fertility (Williams 1975): Fertility refers to the probability of reproducing now (short term), whereas reproductive value is the probability of reproducing in the future (long term). A 10 year old girl would have high reproductive value, but low fertility, whereas a 30 year old woman may have high fertility, but a low reproductive value. Youthfulness would be an indicator of both reproductive value and fertility. This could be signalled by physical characteristics such as smooth skin, good muscle tone, full lips and healthy hair, or by behaviour such as high energy levels or a sprightly gait (Symons 1979). Males who select females with youthful characteristics will therefore father more offspring than men who chose females without.

• Prediction: As female fertility is closely related to age, we would predict that men would show a preference for younger, physically attractive women, or women who showed signs of youthfulness. As men are fertile their whole life, and so their fertility is less closely related to age, this preference for youth and physical attractiveness should be much more pronounced in men than in women.

3. Prediction based on paternity probability (Daly et al, 1982): In humans, while the bulk of parental investment is shouldered by females, males do contribute, and so they want to ensure that any time and effort invested is directed towards their own offspring rather than those of another male. Paternity probability refers to the probability that the offspring that a male is investing in is actually his own. Sexual jealousy is a means of increasing paternity probability as it “guards” their mate and dissuades male competitors. Daly goes as far as to state that in humans many murders and much violence stem from male sexual jealousy. Another means would be a preference for chastity in a mate. Males who desire females who have no other lovers would raise his paternity probability.

• Prediction: males should show a preference for women who are chaste, and should also show greater sexual jealousy than women. Because women can be certain that any child they produce is theirs, they should have less need for chastity in males. However, it is possible that male sexual experience may signal that the male has to share resources between a number or females and/or children. Therefore, chastity might be important for females.

Aims

Buss aimed to investigate if evolutionary explanations for sex differences in human mate preferences are found in cultures with varying ecologies, locations, ethnic compositions, religious orientations and political inclinations. Cross-cultural studies provide an opportunity for testing evolution-based hypotheses because we would expect behaviours that are innate to be the same in all cultures.

2. PROCEDURES (pg117)

|Who were the participants? |Buss used 37 samples from 33 different countries, located on six continents and five islands, creating a |

| |total number of participants of _____________. The samples varied in size from 55 in ____________ to 1491 |

| |in ___________. Apart from _____________ all samples were greater than 100. |

| |The average sample size was 272participants |

| |_______________ were male, ________________ were female |

| |The average age of participants was __________________ |

|Research method used? |Questionnaire (cross cultural comparison) |

|Variables |IV: sex of participants, DV: factors effecting mate preference |

• The sampling techniques varied widely across countries:

| |Sampling method: |

|In Estonia one sub sample consisted of couples applying for a marriage licence | |

|In Venezuela the sample consisted of every fifth household in a series of neighbourhoods | |

|that varied in socioeconomic class | |

|In South Africa the Zulu sample consisted of a rural population some of which had the | |

|questions read aloud to them | |

|In West Germany the sample was selected through newspaper ads | |

|In New Zealand the sample consisted of high school students taken from three schools | |

• The data was collected in most cases by native residents of each country and mailed to the USA for analysis. The research collaborators were unaware of the aims of the study.

The Questionnaire

Buss used two methods to assess the participants’ views on mating preferences

| |3 |2 |1 |0 |

|Good cook and housekeeper | | | | |

|Pleasing disposition | | | | |

|Sociability | | | | |

|Similar education background | | | | |

|Refinement, neatness | | | | |

|Good financial prospects | | | | |

|Chastity | | | | |

|Dependable character | | | | |

|Emotional stability/maturity | | | | |

|Desire for home and children | | | | |

|Favourable social status | | | | |

|Good looks | | | | |

|Similar religious background | | | | |

|Ambition and industriousness | | | | |

|Similar political background | | | | |

|Mutual attraction – Love | | | | |

|Good health | | | | |

|Education and intelligence | | | | |

Instrument 1: Rating

• Part 1 Biographical data: this was information about the participant themselves e.g. age, sex, religion, marital status, number of brothers and sisters.

• Part 2 Mate preferences: the questions were general questions regarding choosing a mate e.g. questions about the age at which they would prefer to get married, what age difference (if any) would they prefer between themselves and their spouse, how many children they desired etc.

• Part 3 Rating Scale: these questions aimed to investigate what characteristics a participant looked for in a mate (see right). Participants had to rate 18 characteristics on a four point scale from 3 (indispensable) to 0 (unimportant). Mixed in with these 18 were the four target variables: good financial prospects, good looks, chastity (no previous sexual intercourse) and ambition and industriousness.

Instrument 2: Ranking

Participants were asked to place 13 characteristics in rank order based on their desirability in someone they may want to marry. Rank 1 was given to the most desirable characteristic, rank 2 to the second most important and so on down to rank 13. Among these 13 characteristics were the two target variables: good earning capacity and physical attractiveness. Other variables included being religious, being kind and understanding, and having an exciting personality.

Translations

Research collaborators had the task of employing three bilingual speakers: one translated the questionnaire from English into their native language, the second translated the answers back into English, and the third resolved any discrepancies. The translators were instructed to make sure all the terms were neutral rather than using words that might be linked to a specific sex. For example ‘physically attractive’ is neutral, whereas ‘handsome’ and ‘beautiful’ are sex-linked.

Occasionally, questionnaires needed to be amended to reflect the cultural differences. In Sweden, many couples do not get married, but just live together, so the questions had to be modified to reflect this cultural difference. In Nigeria, men often have more than one wife (polygyny), and so the questions had to be altered to reflect the possibility of multiple wives.

FINDINGS AND CONCLUSIONS (pg 118-9)

Findings

Significance recap: some of the results below talk about ‘statistical significance’. If a result is statistically significant, it means that there is a less than 5% probability that the results came about by chance. If a finding is reported, but is not statistically significant, it means that the probability of the results having come about by chance are more than 5%. In psychology, we do not draw conclusions from such results.

Good financial prospects

In 36 of the 37 samples (97%) females valued ‘good financial prospects’ in a mate more highly than did males. The sole exception was Spain, where there was a difference in the predicted direction, but it was not significant.

There was considerable variation in how much this mate characteristic was valued. In general, Western European samples valued earning capacity less than South American, North American, Asian and African samples, although there were variations among samples within countries.

Ambition and Industriousness

In 34 of the 37 samples (92%), females expressed a higher valuation for ambition and industriousness in a mate than males did. In 29 samples (78%), this difference was statistically significant providing more support for the theory of sex differences.

In three samples, (Columbia, Spain and South African Zulus) the opposite sex difference was found - males rated ambition and industriousness more highly than females did, although it was only significant in the South African Zulu sample. The research collaborator for the Zulu sample suggested that this may be because physical tasks, such as building the house are considered to be woman’s work. Males in this culture usually commute from rural to urban centres to work.

Both sexes in the Nigerian, Zulu, Chinese, Taiwanese, Estonian, Palestinian, Columbian and Venezuelan samples placed a high value on this mate characteristic. This characteristic was not rated low in any sample, although samples in The Netherland and Great Britain, West Germany and Finland expressed the least amount of preference for it.

Age Difference

In all 37 samples, males preferred mates who were younger. The mean age difference preferred by males was 2.66 years younger, and the mean age at which men prefer to marry is 27.49 years. This therefore suggests an ideal age for females of 24.83 years, which is closer t the peak female fertility rather than the peak female reproductive value.

Across all countries, females preferred mates who were older. The mean desirable age difference was 3.42 years older, and the mean age that females prefer to marry is 25.39. Therefore ideal mate age is 28.81 years.

In cultures where polygyny was substantial, male preference for being older was at its largest: 6.45 (Nigeria) and 7.38 (Zambia). This could be because males tend to be older when they acquire wives in polygynous systems compared with monogamous (one partner) mating systems.

Good Looks

All of the 37 samples showed that males rated ‘good looks’ in their mate more important than females did. This differences was statistically significant in 34 (92%) of the samples. Good looks were particularly important to males in the Bulgarian, Palestinian, Nigerian and Zambian populations.

Chastity

Samples varied tremendously in the value placed on chastity. In 23 (62%) of the samples, males preferred chastity in their mates, whereas there was no significance in the remaining 14 samples. Samples from China, India, Indonesia, Iran, Taiwan and Israel (Palestine) attached a high value to chastity in a potential mate. Chastity was viewed as irrelevant or unimportant in most of the Western European samples.

Validity

Before drawing conclusions from this research, two questions need to be answered:

1. Do self reported preferences accurately reflect actual preference?

2. Do mate preferences accurately reflect actual mating decisions?

In 27 of the 33 countries sampled, demographic data were obtained. The mean age difference was found to be 2.99 years which is very close to the mean preferred difference found in this study (2.66 for males and 3.42 for females: the mean is 3.04 years).

The preferred age for marriage given in the study also closely matched actual age. For example, males in this study suggested the mean age for marriage would be 27.5, and the actual mean age is 28.2. For females, the mean preferred age was 25.4 and the actual mean age was 25.3.

All of this seems to suggest that the results from this study accurately reflects both mating preference and mating decisions, and therefore increases the validity of the results.

Conclusions

Five evolution-based predictions received support from the data.

1. Females valued the financial capacity of potential mates more than males did. This supports the hypothesis that women seek cues related to resources (supporting __________________ from the aims and context)

2. Females valued ambition and industriousness more than males did, again, supporting the hypothesis that women seek cues related to resources (again supporting __________________ from the aims and context)

3. Males value physical attractiveness and relative youth more than females did, supporting the hypothesis that males seek cues related to high reproductive capacity (supporting ____________________ from the aims and context). The fact that males sought partners around the age of 25 suggest that they look for cues related to fertility rather that reproductive value. This goes against Symonds (1979) view that reproductive value is more important for males. However, the ideal age preference was actually a few years beyond the peak female fertility, suggesting that non evolutionary factors may also be involved, such as compatibility and maturity.

4. Females preferred somewhat older mates. This was not specifically predicted at the outset, but supports the importance of resources because older men would be likely to have greater resources (supporting __________________ from the aims and context).

5. Males valued chasitity more than females did, supporting the importance of paternity probability (supporting __________________ from the aims and context) although only modestly as large numbers of samples showed no difference. These less impressive results could be that chastity (unlike physical attractiveness and age) is not directly observable.

How do Buss’s findings support the general notion of mating behaviour being innate?

• Buss also concluded that mating behaviour differs by gender, and that these differences reflect the differences in the reproductive capacities of males and females.

• Buss also concluded that, unlike other animals, human mate preference is not simply about female choosiness. Human males and females both express preferences and there are evolutionary reasons for doing so.

• However, while he showed the importance of evolutionary explanations for mating behaviour, Buss also highlighted that there are cultural influences as well. This is demonstrated by the large differences in preferences for chastity between cultures.

EVALUATING THE METHODOLOGY (pg 120)

Method:

• Buss used a questionnaire to gain his data. What are the strengths and weaknesses of using a questionnaire in this study? (use your notes on questionnaires)

• Are there any issues with the questionnaire itself? What types of questions were used, and could these present problems?

Reliability:

• Could this study be replicated?

• The participants were only given the questionnaire once. How could this affect reliability?

• Buss used two different measures/instruments with the participants. How does this improve reliability?

Validity:

• Efforts were made to ensure that all participants fully understood the questions asked. The questions were translated into local languages, the questionnaire was read out to those who could not read, and questions were tailored to match local customs. To what extent do you think the answers provided accurately reflected the true thoughts and feelings of the participants?

• Could the fact that some participants received slightly different versions of the questionnaire, or had it read to them instead of reading it themselves affect the validity of the results?

• Could the results have been affected by a social desirability bias?

• Can we be certain that the responses that the participants gave actually reflect their real mate choice?

• In one of the samples, some participants had the questions read to them. Could this affect validity?

• Although the questionnaire was translated and adapted for various cultures, it was still made by a Western scientist, who would have his own preconceived notions about relationships. Could this affect the validity of the questionnaire? Might there be things missing from the questionnaire that would not apply to Western relationships, but might in other parts of the world?

Sampling:

• Buss’s sample size was 10,047. What is the advantage of this?

• The mean age of all participants was 23.49 for males and 22.52 for females. Could this have affected the results? Would the results have been different with different age groups? Considering that he was interested in mate selection would it have been appropriate to use other ages?

• The sampling methods varied drastically from one culture to another. Could this act as an extraneous variable?

• Buss acknowledged that many of the samples were unrepresentative of the target population, in particular rural and less educated people were less represented. How could this affect the results?

• Buss aimed to have samples of as many different types of people as possible. However, over 77% of the participants were from westernised industrialised nations. How might this affect the validity?

Ethical issues:

• Can you see any ethical issues in Buss’s research?

CRITICALLY ASSESS WITH REFERENCE TO ALTERNATIVE EVIDENCE

Buss found that physical attractiveness was rated as important by the vast majority of males. However, his research is limited in its explanation of what particular factors are considered to be attractive. We would assume that if mate selection has been shaped by evolution, then all people should agree on what is attractive. If each culture had a different idea of what defines physical attractiveness, it would be unlikely to be due to evolution.

Cunningham et al (1995) found very close agreement across cultural groups when rating female physical attractiveness. In this study, recently arrived native Asians and Hispanic students and white Americans rated the attractiveness of Asian, Hispanic, black and white women in photographs. The mean correlation between groups in attractiveness ratings was +0.93.

Evolutionary explanations would also predict that the traits that are seen as physically attractive give cues about health and fertility. Singh (1993) found that waist to hip ration (WHR) was related to physical attractiveness across many cultures. Men prefer women who have a low WHR (the ideal being around 0.7). A woman with this WHR is likely to have a large bottom, indicting good fat reserves for pregnancy, and a narrow waist, indicating that she is not pregnant. Thus the reason that a low WHR would be attractive is that it is a sign of youthfulness and fertility.

It has been proposed that facial symmetry is a sign of genetic strength, as a number of genetic disorders cause asymmetrical faces. Therefore, we should find symmetrical faces more attractive as it would lead to more successful reproduction. Little et al (2007) examined preferences for symmetry in both the UK and the Hadza, a primitive hunter gatherer society in Tanzania. Both groups preferred symmetrical faces, and this was the strongest in the Hadza.

The Babyface hypothesis: There are other possible evolutionary explanations why there are universal standards of beauty. It may not just be that such traits imply fertility – they are also associated with a ‘baby face’; a high forehead, big eyes, small nose and chin. Adults may have evolved a preference for baby features because this ensures that we care for our young and for this reason, such features elicit attraction. However Cellerino (2003) suggests that these same features are signs of high levels of oestrogen, again, suggesting fertility.

What did Schmitt (2003) find? (Pg151) What does this suggest about Buss’s study?

One potential issue with Buss’s research (which he did address to some degree) is the extent to which people’s stated preferences actually reflect their real mating decisions. Lonely hearts adverts are an easy to access source of quantifiable data on human mate choice. Such ads let us see what specific traits men and women seek in a mate.

Waynforth and Dunbar (1995) performed a content analysis on 900 ads from four American newspapers. The ads were sorted into 10 year age groups (20-29, 30-39, etc) and scored the frequency with which they mentioned certain key terms related to the following categories; physical attractiveness, wealth/status/family commitment, sexual fidelity, tolerance of children, and age requirements. They found the following differences in the ads posted by men and women:

• More men than women sought a youthful mate

• More men sought a physically attractive mate

• More women used physically attractive terms to describe themselves

• Ore men reported their economic status/earning power when describing themselves.

An issue with Buss is that he focused exclusively on heterosexual relationships. This means that his results may not be applicable to gay and lesbian relationships. In a later study Dunbar (1995) looked at gay personal ads, and found that heterosexual women were three times more likely to seek resources and status then lesbians, and gay men offered resources about half as often as heterosexual men. This supports the evolutionary explanation because we would not expect lesbian and gay mate choice to be related to reproductive criteria.

Dunbar also notes that times have changed, and that many women have their own economic security, and are less interested in a partner’s resources. They therefore seek a caring and sharing partner rather than one with resources. This still makes evolutionary sense because that kind of partner should still enhance reproductive success.

Use three colours to highlight research that supports, contradicts, or develops Buss’s research.

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Recapping the Evolutionary Approach

The last study we looked at was Bennett-Levy and Marteau, where we explained the development of animal phobias as being an adaptation that our ancestors evolved as a way of surviving long enough to reproduce. This core study is also based on the assumption that human behaviour has evolved and that behaviour shown by modern humans would have given our ancestors an advantage in the “survive and reproduce” stakes. However, whereas Bennett-Levy and Marteau investigated how humans react to other animals, Buss is more interested in how humans react to other humans. Specifically, we are looking at sexual selection or mate selection; how do humans decide who to breed with?

If we assume that human behaviour evolved, we should be able to predict what behaviour would lead to more successful reproduction. For example, the behaviour “avoid the opposite sex” would prevent that organism from reproducing. Therefore that characteristic would soon become extinct as it would not be passed on. However, the characteristic “have sex with as many members of the opposite sex as you possibly can” would lead to increased reproduction, meaning that characteristic or gene would be passed on to the offspring, who would pass it to their offspring and so on. However, as we will see, this is a very simplistic view, and human mate selection is much more complex than this! Successful reproduction is not just about quantity, but quality. It would be little use to have 20 children who all died before they could reproduce themselves. Also, men and women have different agendas for reproduction, leading to an evolutionary “battle of the sexes”! Hence the title of this study Sex differences in human mate selection.

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