Babies anticipated the stimulus that they knew would be presented in a familiar color pairing, suggesting that they developed an expectation of what they would see on one side of the screen.
The figure shows another interesting result: Unlike in the first study, there was no difference in the ability to anticipate a stimulus between vaginally-delivered babies and infants delivered by caesarian.
Does this mean the first result might have been a one-time event; some sort of statistical fluke? No, because the same effect was also present in the second study when eye movements were analyzed with respect to stimulus onset (I am not showing those data here to keep things simple).
The effect of birth experience was thus observed in both studies, but only in response to stimulus-driven cueing of attention. By contrast, there was no effect of birth experience on attentional behavior that was driven by learned, cognitive expectations. This rather subtle pattern isolates the specific attentional ability that may be affected by birth experience; namely, the efficient responding to a visual cue.
Adler and Wong-Kee-You underscore the importance of their findings by highlighting the fact that the number of caesarean sections being performed has been steadily increasing. Several professional bodies, such as the American College of Obstetricians and Gynecologists, and the Society for Maternal-Fetal Medicine
, have expressed concern about this trend for a number of health-related reasons. The work of Adler and Wong-Kee-You adds a cognitive dimension to this concern.
Should these results necessarily alarm expecting mothers who are considering delivery by caesarian? Probably not. The size of the effects observed by Adler and Wong-Kee-You is not unlike that observed as a consequence of the mother receiving an epidural during a vaginal birth
. Moreover, many other factors also affect cognitive development, such as breast feeding
, or brain structure, such as raising a child bilingually
, that are not always under the parents’ control.
It is valuable to know about those factors, but it does not follow that one has to forsake an epidural, avoid a caesarian, and seek a husband whose native language is not English in the interest of one’s baby. The most important factor for a person’s long-term well-being is emotional health in childhood
, and there is no evidence to suggest that this is affected by birth experience.