Newborns already store words using speaker identity
A four-day-old infant can already recognise a familiar word. And how well they do it depends on who is speaking. That tells us something important about how memory and language are intertwined from the very first days of life.
Researchers tested newborns aged zero to four days using near-infrared spectroscopy (fNIRS), a method that measures brain activity via infrared light. Infants heard a word repeatedly, then an interfering sound, then the word again. The question was whether they would still recognise it.
They did, but only when the word was spoken by a different voice the second time. When the same speaker was used, the interfering sound caused more confusion. A change of speaker helped the infants separate the word from its context, storing them as distinct memories.
Where in the brain this happens
The study, published in eLife, found that recognition was linked to increased activity in areas also involved in language processing in adults: the left inferior frontal gyrus and superior temporal gyrus. The right hemisphere was also active, in regions associated with recognising speaker identity.
An early foundation for episodic memory
This is relevant to understanding how memory develops across the lifespan. The ability to bind ‘what’ and ‘who’ in a memory is considered a precursor to episodic memory: the capacity to store and retrieve specific experiences. That capacity declines with ageing and is among the earliest functions lost in dementia. Understanding how it forms, from the very first day of life, may illuminate why it becomes vulnerable later on.