4.1 Cultural Experience and Sensation

Our senses of taste, smell, touch, hearing, and sight are developing in utero, with sight being the least developed due to the darkness experienced by the fetus in a mother’s womb. This is an important period of brain development during which the fetus’s brain undergoes experience-expectant plasticity. Experience-expectant plasticity refers to the creation of brain synapses primarily through sensory experiences, such as vision, taste, smell, and hearing, but also as a result of humans’ expectation that they will be cared for in infancy by a responsive, loving caregiver. This means our brains are prewired to build synapses related to senses and caregiving. In addition, experience-dependent plasticity is happening during this time. Experience-dependent plasticity refers to the creation of synapses that are dependent on a fetus’s individual and unique experience. How do we know that fetuses learn from their experiences in utero? Researchers have been able to document instances of fetal learning using several methods, including (1) fetal heart rate habituation studies, whereby a fetus’s heart rate increases when exposed to a new stimulus and then decreases once the stimulus becomes familiar and the fetus has learned about the stimulus (Muenssinger et al., 2013), and (2) infant preferences for sounds, tastes, and smells shortly after birth (Schaal et al., 2000; Mennella et al., 2001).

Infants show preferences for the smells and tastes they experienced as fetuses within their mothers’ amniotic sac (Schaal et al., 2000), as well as for the food ingested by their mothers while the infants are breastfeeding (Mennella et al., 2001). This means that infants show a bias toward the foods and the odors of the foods that their mothers eat. Often, what a mother eats during pregnancy is a function of cultural norms and preferences. For example, mothers who ingest anise during pregnancy and during the fetal stage of development (~12 weeks–38 weeks) give birth to infants who prefer the smell of anise compared to the infants of mothers who do not eat anise (Schaal et al., 2000). In another study, mothers were asked to drink either carrot juice or water a few hours before breastfeeding. Infants were then fed carrot-flavored cereal, and those whose mothers had consumed carrot juice ate the cereal without resistance and ate more of it compared to the infants who hadn’t been exposed to the carrot flavor through their mother’s breast milk (Mennella et al., 2001). Surprisingly, these preferences are observed in infants when they begin to eat solid food, suggesting the effects of prenatal experiences can be long lasting. Thus, a human’s exposure to varying spices and flavors both prenatally and while breastfeeding has cascading effects for later smell and taste preferences.