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January 19, 2005

Difference day 1

I am quoting a few paragraphs from pages 55-56 of The Essential Difference which suggests that newborns (one day out of the womb!) express non-trivial differences in terms of behavior when categorized by sex.

BEGIN QUOTE ...They videotaped over 100 babies who were just one day old, in the Rosie Maternity Hospital in Cambridge, England. Little did these babies know what lay in store for them. No sooner had they emerged from the womb than they were recruited into this scientific study. The babies were shown Jennifer's tanned Californian face, smiling over their crib. Her face moved in the natural way that faces do. They were also shown a mobile. But this mobile was no ordinary mobile. It was made from a ball the same size as Jennifer's head, with the same coloring (tanned), but with her features rearranged, so that the overall impression was no longer face-like. Around the lab we called it The Alien. To make it look more mechanical, we hung some material from it that moved every time the larger mobile moved. In this way, we could compare the baby's interest in a social object (a face) and a mechanical object (a mobile)>. Finally, in order for the experimenters to remain unbiased, mothers were asked not to tell the researchers the sex of her baby. This information was only checked after the videotapes had been coded for how long each baby looked at each type of object. So the question was, would babies look longer at Jennifer's face, or at the mobile. When we analyzed the videotapes, we found that girls looked for longer at the face, and that boys looked for longer at the mobile. And this sex difference in soical interest was on the first day of life. END QUOTE

The original paper (PDF).

Here are some tables with data....

Number (and percent) of neonates falling into each category

 Face preferenceMobile preferenceNo preference
Males (n=44)11 (25%)19 (43.2%)14 (31.8%)
Females (n=58)21 (36.2%)10 (17.2%)27 (46.6%)

Mean percent looking times (and standard deviation) for each stimulus

Male45.6 (23.5)51.9 (23.3)
Female49.4 (20.8)40.6 (25.0)
Posted by razib at 12:56 AM