Sunday, April 8, 2012

Spatial ability and socio-economic status

One of the most persistent, and pronounced, findings in gender differences with regards to cognitive performance has to do with spatial skills, in general, and Mental Rotation, in particular (see Linn & Petersen, 1985) - a gap that, except for some notable exceptions (Eastern Canadian Eskimos and Icelanders), seems to hold cross-culturally (Mann, Sasanuma, & Sakuma, 1990).

Fig 1 from Levine et al. 2005

In their 2005 paper -Socioeconomic status modifies the sex difference in spatial skill - Levine, Vasilyeva, Lourenco, Newcombe, and Huttenlocher present the results of a longitudinal study that ran over two years with the intention of investigating what, if any, effect Socioeconomic Status (SES) has on this gender gap in spatial ability. In understanding the differences between male and female spatial skills it's essential to get a handle on whether the observed differences are mainly a function of biology or mainly a function of culture, given that generally any interesting trait is going to be affected by both. This is especially important in the present case because it has been shown that spatial skills tend to correlate with performance in mathematics based subjects - areas where females have traditionally been under-represented. Understanding this gender based performance difference may help enable educators better address the disparity of representation in STEM subjects (see, for example, Cherney, 2008).

SES status was assigned at a school level on the basis of census-track data for Illinois. A total of 547 students were recruited for the experiment, with male and female participants being approximately equally represented across all three SES groups. Testing consisted of administering an aerial-map task (participants are asked to draw correspondences between aerial photographs of an area and a map of the same area), a mental rotation task (based on "the Spatial Relations subtest from the Primary Mental Abilities (PMA) Readiness Level" (Levine et al., 2005: 842)), and a syntax comprehension test. 

Given previous findings, Levine et al. expected to see gender differences in the spatial tasks but not the language task - an expectation that was mostly borne out by their results with one exception. Their findings show (fig 1) that the expected differences in spatial skill held only for middle and high income subjects - low SES male and female subjects failed to show any significant differences in their performance on the aerial-map and mental rotation tasks. That is, in Levine et al's study, the gender gap is virtually non-existent for the low income group. 

The researchers posit two possible explanations for their findings. The first starts with the observation that generally the gender difference manifests itself in the more difficult test items - if both male and female low-SES group subjects failed to succeed in answering the more difficult questions then that difference wouldn't be apparent in the data even if a difference did in fact exist. However, further analysis of their data seems not to support this hypothesis, for example, a difference in spatial ability for the low-SES group did not manifest in the subset of data where performance across all three groups was comparable for spatial tasks while the difference persisted for the higher groups. 
The second possible explanation for the results, and the one the researchers (and their data) seem to favour, is the notion that it is "differentially high level[s] of engagement in the kinds of activities that promote the development of spatial skill[s]" (Levine et al., 2005: 884) that causes the gender gap in spatial ability, and that these kinds of activities (playing with particular toys, freely exploring their neighbourhoods, etc.) might not be readily available to males from low-SES groups, or - at least - as readily available to males as they are to females. 


References:

Cherney, I. D. (2008). Mom, Let Me Play More Computer Games: They Improve My Mental Rotation Skills. Sex Roles, 59(11-12), 776-786. 

Levine, S. C., Vasilyeva, M., Lourenco, S. F., Newcombe, N. S., & Huttenlocher, J. (2005). Socioeconomic status modifies the sex difference in spatial skill. Psychological science, 16(11), 841-5. 

Linn, M. C., & Petersen, A. C. (1985). Emergence and Characterization of Sex Differences in Spatial Ability: A Meta-Analysis. Child Development, 56(6), 1479. 

Mann, V., Sasanuma, S., & Sakuma, N. (1990). Sex differences in cognitive abilities: A cross-cultural perspective. Neuropsychologia, 28(10).

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