Women & driving…
In the past couple of weeks I have been researching gender differences in visuo-spatial abilities because I wanted to create a fun experiment for our research & methodology course. The idea came from a recent incident in which my (fairly new) car, perfectly still and parked on an wide entry road to a private car park was scratched by a runaway vehicle. With 14 years no claim discount from my insurance, you can imagine how annoyed i was when i discovered the damage on a sunday morning!
As the area were I live is usually quiet and frequented mainly by locals, for a few days I have been on the lookout to try to detect the useless driver who caused the damage. Even if I’m still looking, this was an opportunity to observe people manouvering their vehicles and struggle with parking in tight spaces. Furthermore, confirming an old italian say “Donna al volante, pericolo costante!” which best translates as “Women driving are a constant danger”, it was amusing to observe how difficult many female drivers were making what I considered fairly simple manouvres.
I know it is sexist and I know that I will attract criticisms, but let’s start with a short clip…
[myspace]http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=37889811[/myspace]
Now that you laughed about this extreme case, think about your friends and consider these two questions:
[poll id="2"] [poll id="3"]
After the lighter intro, let’s have a look at some of the published material to see what is the truth about gender difference in visuo-aptial abilities.
Informally, people believe that men and women think differently and have different abilities. These differences are exacerbated by books such as John Gray’s Men Are from Mars, Women Are from Venus
Such interest in sex difference raises some interesting questions and folk-facts such as the above about women and driving which inspired this post.
Some differences have been substantiated in the literature in psychology and neuroscience. For example women are consistently showed to be better at performing tasks involving verbal abilities (Hyde & Linn, 1988, Kimura 2000, 2002), however the data regarding visuo-spatial abilities is more controversial and research provided contrasting results.
In a classic experiment on mental rotation task (MRT), in which participant were asked to compare 3d shapes (see figure), Shepard & Metzler (1971) identified a strong effect in performance with males being faster and more accurate in detecting identity between rotated 3d shapes.
Other studies showed a gender difference in spatial abilities (intended as navigational abilities) with males performing better at this task. For example, Silverman & al (2007), in a large study conducted in association with the BBC, found that men scored significantly higher than women on a test of three-dimensional mental rotations in seven ethnic groups and 40 countries used. In addition, women scored significantly higher than men on a test of object location memory in all seven ethinc groups. They interpreted the data at the light of evolutionary competencies based on the hunter-gatherer theory. In the past few years, Collaer (2004, 2007) showed a marked sex difference in another task involving mental rotation in a line orientation judgment which removed the complexities of the original MRT and still identified a strong difference.
The behavioural results have been replicated many times (see Kosslyn (1980, 1994) and Shepard and Cooper (1982) for reviews); evidence from a meta-analytic study conducted by Soares-Masters and Sanders (1993) of studies spanning 15 years of research, confirmed that males scored significantly higher at the MRT task than females in all the studies. Analyses of the effect size computed for the studies revealed that the magnitude of the gender difference on the MRT has remained stable over time.
In support of the discrepancy of results caused by instruction and/or task type, Parson & al (2004), for example, testing participants with a paper and pencil and a virtual reality-based (VR) version of the mental rotation task, showed that even though in the paper-based version they replicated the gender difference, this was not the case in the VR task. They discussed their findings in terms of task demands and motor involvement.
Interestingly, in a recent manipulation of the MRT experiment Moe’ and Pazzaglia (2006) clearly demonstrated a self-fulfilling prophecy effect caused by the beliefs in participants’ ability (and the potential stereotype associated with gender). Their data showed that those who expected to be more able than the opposite gender (established in the experimental instructions) outperformed their counterparts and that MRT performance fell for those expecting to be less able. The effects of induced beliefs on cognitive performance were stressed and the obvious implications for the educational context, in which gender stereotypes still reign in some disciplines, were addressed.
What are the abilities required to perform these tasks? In the original paper Shepard & Metzler argued that the mental rotation in the mind was supported by the apparent linear increase in reaction times with the increase of the angular rotation of the shapes. Similar effects were also found by some with other types of stimuli such as letters and two-dimensional shapes, however Kosslyn argued that the difference in performance could be caused entirely by the way in which males and females interpret the task and performed it.
Even though differences were found, the MRT experiment has been often criticised because the task specifications were not clear enough, that it is particularly affected by training and that when the wording of the task were changed women seemed to be as good as men at the task.
Nevertheless, little is known yet of the neural mechanisms that underlie mental rotation. Most of the research on the neural basis of such processing has focused on its possible cerebral lateralization, hence the implicit association with a gender differentiation of abilities.
With the recent developments of brain imaging techniques, Cohen & al
showed that there are some differences in the areas of activation in the brain, however it is difficult to draw conclusions on gender differences based on a small number of pariticipants. There is also some evidence that there are gender differences in the brain from a biological perspective (Gur & al 2008 and Leonard & al 2008). Gur & al were able to measure neuroanatomical differences in the brain and confirmed that women have a higher percentage of gray matter, whereas men have a higher percentage of white matter. They concluded that sex difference in the percentage and asymmetry of the principal cranial tissue volumes may contribute to differences in cognitive functioning. Leonard & al also showed that in a bigger sample (200 participants) there were individual differences in cerebral volume which accounted for 21% of the difference in gray matter proportion, while sex accounted for an additional 4%. The relative size of the corpus callosum was 5% larger in women, but this difference was completely explained by a negative relationship between relative callosal size and cerebral volume.Neuroanatomical diferences are more controversial than experimental studies as there seems to be an implicit acceptance that if there are differences, these reflects in cognitive functioning as well as.
From this partial overview of the literature, it seems that there is no doubt that sex difference in visuo-spatial abilities are real, but what does this mean in practice, especially for what concerns our driving stereotype?
Well, it is difficult to say… The type of tasks involved in driving rely heavily on visuo-spatial abilities and a coherent mental representation of the world surrounding the driver. As we’ve seen if women do believe to be bad in performing a parallel reverse parking it is very likely they will do an awful job at it.
There is also no doubt that insurers believe that women are safer drivers: certainly testosterone-driven male drivers are more aggressive, however I was also very much puzzled by the paper by Hausmann & al (2000) in which they explored hormonal effects on spatial abilities by testing women during their menstrual cycle. They found that testosterone
had a strong and positive influence on mental rotation performance, whereas estradiol had a negative one.
From all this my conclusion is somehow simplistic: stay away from women driving when they are in the mid-luteal phase as they might be more erratic than usual…
References
- Becker, J.B & al (2008) Sex Differences in the Brain: From Genes to Behavior
, OUP, USA
- Cohen, M.S. & al (1996) Changes in cortical activity during mental rotation A mapping study using functional MRI. Brain, Vol. 119, No. 1, 89-100, 1996. [http://brain.oxfordjournals.org/cgi/content/abstract/119/1/89 ]
- Collaer,ML, Nelson, JD (2002) Large Visuospatial Sex Difference in Line Judgment: Possible Role of Attentional Factors – Brain and Cognition, 2002
- Gur, R.C. & al (2008) Sex Differences in Brain Gray and White Matter in Healthy Young Adults: Correlations with Cognitive Performance. The Journal of Neuroscience, May 15, 1999, 19(10):4065-4072 [http://www.jneurosci.org/cgi/content/abstract/19/10/4065]
- Halpern, D.F. (2000) Sex Differences in Cognitive Abilities
, Lawrence Erlbaum Associates.
- Hausmann, M & al (2000) Sex Hormones Affect Spatial Abilities During the Menstrual Cycle. Behavioral Neuroscience, Vol. 114, No. 6, 1245-1250.
- Kimura, D. (2002) Sex Differences in the Brain – Scientific American, Special Editions, 2002
- Kimura, D. (1999) Sex and Cognition
, MIT press.
- Kosslyn SM. (1980) Image and mind. Cambridge (MA): Harvard University Press.
- Kosslyn SM. (1994) Image and brain: the resolution of the imagery debate. Cambridge (MA): MIT Press, 1994
- Leonard, C.M.& al. (2008) Size Matters: Cerebral Volume Influences Sex Differences in Neuroanatomy. Cerebral Cortex (in press, http://dx.doi.org/10.1093/cercor/bhn052)
- Linn, M.C and Petersen, A.C. (1985) Emergence and Characterization of Sex Differences in Spatial Ability: A Meta-Analysis. Child Development, Vol. 56, No. 6 (Dec., 1985), pp. 1479-1498
- Moe’, A. & Pazzaglia, F. (2006) Following the instructions! Effects of gender beliefs in mental rotation. Learning and Individual Differences. Volume 16, Issue 4, 2006, Pages 369-377 [http://dx.doi.org/10.1016/j.lindif.2007.01.002 ]
- Parson, T.D. & al (2004) Sex differences in mental rotation and spatial rotation in a virtual environment. Neuropsychologia. Volume 42, Issue 4, 2004, Pages 555-562
[http://dx.doi.org/10.1016/j.neuropsychologia.2003.08.014 ] - Shepard, R. N., and Cooper, L. A. 1982. Mental Images and Their Transformations. MIT Press, Cambridge, MA.
- Shepard and Metzler (1971) Mental rotation of three-dimensional objects. Science 171 (1971), pp. 701–703.
- Silverman, I., Choi, J., & Peters, M. (2007). The hunter-gatherer theory of spatial sex differences: Data from 40 countries. Archives of Sexual Behavior, 36. [http://www.springerlink.com/content/g2044m43125lj832/]
- Soares Masters, M. & Sanders B. (1993)
Is the gender difference in mental rotation disappearing? Behaviour Genetics, Volume 23, Number 4 / July, 1993. [http://www.springerlink.com/content/p128326282275112/ ] - Sack,A.T. & al.(2008) Dynamic Premotor-to-Parietal Interactions during Spatial Imagery. J. Neurosci., August 20, 2008; 28(34): 8417 – 8429.
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