Can the fetus hear, smell and taste?

For thousand years there has been speculated regarding the abilities of the human fetus. The problem has become actual in the last years which have seen a lot of debates regarding the status of the fetus moving into the social and political arena. Discussion about abortion, embryo research, in vitro-fertilization have draw on studies of fetal behaviour to support a particular viewpoint.

The scientific studies have been focused on fetal memory because it is difficult to imagine an intellectual or behavioural activity without memory. For many years it was thought the newborn infant did not possess a functioning memory, but studies of newborns and premature infants have changed this view. Newborns have been show a variety of learning paradigms, habituation, classical conditioning, exposure learning. These are the experimental steps to prove that the fetus has a functioning memory.

  • HABITUATION - can be defined as the decrement in response following repeat presentation of the same stimulus.
  • CLASSICAL CONDITIONING - involving the pairing of two stimuli, the conditioned stimulus and the unconditioned stimulus. The unconditioned stimulus elicits a response when presented alone. The conditioned stimulus elicits no reaction when presented alone. However following a number of pairings, the conditioned stimulus elicits a responce.
  • EXPOSURE LEARNING - consists to expose the fetus to a stimulus and then observe its response after a number of exposure.

In many experimental studies the fetus had shown the capability to change his behaviour in response to the stimuli. Auditory, vibroacustic, olfactory stimuli were utilized and the fetuses shown a variable capability to learn and memorize a particular sound or the maternal voice and language, a fairy tale, the smell of garlic.

The important question now about the fetal memory is what functions does it serve?

It is likely that memory begins prenatally and the period of birth merely marks a transition from memory functioning in utero to memory functioning ex utero. This is not to suggest that memory when it begins to function is capable of all the feats of an adult's memory. Rather memory, at its developmental origin in the prenatal period, probably functions in some rudimentary from and develops, both quantitatively and qualitatively, as the individual matures.

The functions of fetal memory are of central importance.

Fetal memory may serve a "practice and psychological funcions". There is much evidence of other behaviours occuring before the time they are needed. Fetal breathing, eye movements, swallowing, are some example of this.

Fetal breathing- These movements, beginning at 10-11 weeks of gestation, are similar to those exibited after birth to enable breathing. Yet there is no air in the womb.

Eye movements- Coordinate eye mvements occur in the womb in the absence of all but limited visual stimuli.

Psychological functions- It has been considered that behaviours that are crucial for certain stage of development are practised prior to this time to ensure they function efficientely when needed. The same however may hold for crucial psychological functions.

  • Attachment and maternal recognition - Fetal memory may serve a number of specific functions, dependent upon the learning of particular stimuli prenatally. Prenatal memory may be important for the development of attachment and maternal recognition. There is much evidence that the fetus learns the speech caracteristics of its mother prenatally and prefers its mother's voice after birth. It may be that by learning to recognise its mother prenatally the newborn infant has a familiar stimulus in its environment after birth to respond to. As well as enabling recognition of the mother this may also mark the beginning to attachment.

  • Breast feeding - A memory in utero may be important for the estabilishment of breast feeding. The mother's diet flavours both the amniotic fluid and her breast milk. The fetus may learn about the flavour af the amniotic fluid via its swallowing of this fluid begins at 12 weeks of gestation. When presented to the breast for the first time, the newborn infant recognises the colostrum as familiar due to the presence of the same tastes that have been present in the amniotic fluid. This may enhance the individual's willingness to suck and promote breast feeding.

  • Acquisition of language - One final area where fetal memory may be important is in the acquisition of language. It is noted above the ability of the fetus to learn the mother voice. Recordings of the fetal uterine auditory environment, reveal the prosodic nature of speech can be clearly heard inside the womb. Further, the fetus has been shown to be able to discriminate between different speech sounds in the womb. Newborns also seem to have a preference for their mothers' native language. It may be that experience of speech prenatally begins the process of acquiring language.

End of the 1th article. In the next article : "The caracteristics of the fetal hearing"


PG Hepper : Fetal Memory:Does it exist? - Memory in utero? - Fetal Habituation
PG Hepper and BS Shahidullah : Development of fetal hearing
R Restak - Il Cervello del Bambino


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