Back in the 1960’s, a trendy idea in psychology was that babies were born ‘tabula rasa’ – with a completely blank slate of a brain, onto which its experiences would be etched, to shape the person they became.
Even more recently, the newborn baby’s world was often described as a ‘blooming, buzzing confusion,’ as babies gradually make sense of their completely unfamiliar, overwhelming surroundings.
However, since the late 1980’s, some developmental psychology enthusiasts, aided by the development of more sophisticated ultrasound technology, have started to observe more sophisticated neurodevelopment in utero. It started to seem as though babies were better prepared to face the world than was previously thought. This led to the suggestion that babies can learn in the womb – taking a broad definition of learning as a change in behaviour as a result of experience. This idea has attracted a lot of interest, probably because learning is viewed as a desirable achievement, especially by parents, and because it raises interesting questions about the beginnings of life.
From around 27 weeks, foetuses have shown the ability to habituate to certain sounds. When a particular sound was repeatedly presented, foetuses moved around less and less, whilst remaining reactive to new sounds – they grew used to the sound that presented continuously. However, the observations that the speed of habituation decreases as the foetus grows, is related to later developmental outcomes, and is slower in foetuses with Downs Syndrome, would suggest that habituation is closely linked to the foetus’ neural development. Ergo, the significance of habituation in the womb may be as an indicator of development, rather than learning in its own right. This behaviour on its own is probably not sufficient to argue that learning has begun.
Perhaps then, demonstrating a learned association in foetuses would indicate true learning before birth. Research then turned to conditioning, in which a previously neutral event, such as a particular sound, causes a behavioural response after being paired with something which naturally induces a response, such as a vibration on the mother’s abdomen. Around half of the foetuses tested displayed signs of conditioning, but so did foetuses who had significant brain abnormalities, and fellow researchers argued that the method for studying foetal conditioning was not rigorous enough to be useful. What’s more, conditioned responses have been observed in unborn rat pups, and the observation that even invertebrates have shown signs of classical conditioning makes human foetal conditioning seem fairly unremarkable.
However, another approach was producing exciting findings – transnatal learning. Several studies began to show signs that information about things encountered whilst in the womb might be retained after birth. If this were true, then the foetus might be showing signs of learning and memory. Many of the early attempts to demonstrate such learning had a few flaws. For instance, one research teamsimilar experimentResearchersconcerndisappearedpreference for the sound of their own language showed that infants would alter their sucking behaviour in order to hear their mother’s voice, rather than that of a stranger. Whilst that is a perfectly legitimate observation of a preference for their mother’s voice, it does not show that the babies had learned to recognise their mother’s voice whilst in the womb: no attempt was made to account for postnatal exposure to their mother’s voice, which sounds very different from inside the womb, due to occlusion by tissues and fluids.
When a similar experiment was carried out using a filtered recording, to make voices sound as they would have in the womb, neonates also showed a preference for their mother. However, this preference was not found when using whispered voices, so it is possible that the babies were using other cues in the voice, such as emotion, to identify their mother, rather than remembering the sound from before birth.
Nonetheless, some studies do seem to have demonstrated transnatal learning. Researchers instructed a group of mothers to read one of several stories to their baby twice daily for the last 6 weeks of their pregnancy. After birth, the stories were not read at all. The infants who had been read to before birth showed a preference for the familiar story over other stories, unlike infants who had not been repeatedly exposed to the same story. The story was preferred regardless of who was reading – so it would seem that the content of the story (or more likely, its rhythm) had been remembered.
However, there is very little evidence that foetal learning can be used to boost intellectual development. Accounts of superior verbal abilities following exposure to music or rhymes often lack scientific rigour – using individuals without a control group – or are completely anecdotal. There is also a concern that talking or playing recordings directly to a foetus may disrupt its natural sleep/wake cycles, causing stress, which may negatively affect development.
The observation that any evidence of transnatal learning had disappeared by the time infants reached 21 days old also suggests that this learning is not the same as mature long-term memory. If this is the case, then training the foetus is unlikely to have any benefits. It may be that transnatal learning represents a basic and weak form of memory, or is just a by-product of neurodevelopment.
Alternatively, it may be that transnatal learning has a specific purpose, but is discarded when this purpose has been fulfilled. Researchers have suggested that it might aid language development, as neonates appear to show a preference for the sound of their own language, irrespective of time since birth. However, similar preferences have been observed for familiar tastes and smells, so this process is probably not specific to language. More compelling is the idea that transnatal learning forms a sensory bridge between the womb and the world, allowing the infant to adapt to its new surroundings and bond with caregivers.
Either way, it would seem that more complex, higher-order processes that spring most readily to mind at the word ‘learning’ do not begin before birth – but that does not mean that foetal learning is not important.