In my last post we discussed violations of expectation. Now that we understand that eye gaze tells us that a child has ‘learned’ something, we are going to look at an amazing piece of research about understanding human speech.
It’s fairly well known that children can learn languages easier than adults. It’s not simply because a second language is harder to learn than the first, it is because the adult’s brain is different. Why is it so easy though?
The answer may lie in phonemes. A phoneme is the most fundamental part of human speech. Any word we have in English will be made up of a combination of phonemes. Some phonemes are used across most languages, while some are not as common. Take the English “R” and “L” sound. Native English speakers are often surprised that Asian individuals struggle to make this sound correctly (who use English as a second language). This is because the phoneme is not present in most Asian languages and thus they discarded the phoneme long ago. Just as English speakers struggle to correctly differentiate “DAH” versus “DAA”. Both sound identical to me, but what about infants?
Infants can actually clearly hear the difference between all phonemes as shown in the video below. How can you really prove they can tell the difference though? Their research method to prove this was simple, and elegant.
Let’s review what the researchers did.
First, the infant would hear the phonemes ‘DAH’ and ‘BAH’. Every time the ‘DAH’ was played, a light would turn on over the dancing bunny, and the infant would normally look towards it. Eventually, the infant expected the see the bunny whenever it heard the ‘DAH’ sound, as was evident when they delayed the bunny from activating. That is, the ‘DAH’ sound would play, the baby would look up, then a moment later the bunny would activate.
In the second part of the test, the ‘DAH’ phoneme is played with the ‘DAA’ phoneme. These phonemes sound identical to most of us (unless you speak Hindi). The baby would only look towards the bunny when the ‘DAH’ sound was played, not the DAA sound. Clearly, the infant was able to differentiate between these two phonemes.
By using an infants gaze as a measure, we are able to conclude that infants can be universal listeners to the phonemes we create.
Oddly enough, this applies to face recognition in animals. An infant can distinguish the difference between the faces of monkeys, for example, but after a few months old, they lose this ability. This is because the monkeys are not part of their environment. Just as with phoneme recognition, when the information is not used our brains discard it as we do not believe it is needed for our survival. That’s the way it works, for better or worse!