Peter Borkenau, his co-authors and a small army of international research assistants recruited 12,156 college students (52% were female) to fill out a detailed personality questionnaire about "someone they knew well" - either a person younger or older than forty years.
Averaged across all 51 cultures, men's personalities showed more variation for four of the Big Five traits: extraversion, openness, agreeableness and conscientiousness. The exception was neuroticism, which tended to vary more widely in women.
Greater variability in male personalities was not observed in all cultures. In fifteen countries, including Japan and Peru, the pattern was reversed. Across both sexes, personality showed more variation in countries that were more prosperous and had better education systems. Another finding was that female raters showed more variability in the personality ratings they gave, be that for a man or woman. Borkenau and his colleagues said this could explain why past research using self-report questionnaires (where people rate their own personality) has not shown men to have more varied personalities.
The researchers were agnostic as regards the reason why men's personalties show more variability on most dimensions. They said there could be genetic reasons, with traits linked to genes on the X-chromosome in women being averaged across the genetic variants found on each of a woman's two X-chromosomes, thus reducing the likelihood of extreme traits (men have just one X-chromosome, precluding this averaging process).
Whether the reasons are biological or social, Borkenau's team think that sex differences in personality variability probably kick in some time during puberty. They say this based on the fact that a study of children aged 3 to 13, published in 2006, did not find greater variability in the temperament of boys.
Conducting cross-cultural research of this kind is fraught with difficulty because of logistics and translation issues. Realising this, the researchers included measures of data quality, such as missing answers, and they factored this into their analysis. There was evidence that data quality influenced their results, but their main findings held even when controlling for this. Another issue is that men and women's average personality scores differ, with women tending to have higher mean scores. However, the researchers don't think that explains the greater variability in men's personalities - for instance, for several personality facets, men were over-represented in both the high and low extremes.
As with any personality research that relies on questionnaires rather than actual behavioural observations, it pays to interpret the findings of this new study with extreme caution. That male and female students tended to rate men's personalities with more variability might say more about how men are perceived, than about how they actually are. That said, if personality really is more varied in men than women (in most cultures), it joins a list of other characteristics that past research has identified as being more varied in men, including cognitive ability, height and sprint speed.
Borkenau, P., McCrae, R., and Terracciano, A. (2013). Do men vary more than women in personality? A study in 51 cultures Journal of Research in Personality, 47 (2), 135-144 DOI: 10.1016/j.jrp.2012.12.001
Interview with Cordelia Fine, author of Delusions of Gender, in The Psychologist magazine.
Two Myths and Three Facts About the Differences in Men and Women's Brains
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.