Babies learn in bursts (just like Mum said)
US research puts evidence beneath the anecdotes about punctuated learning in infants. Andrew P Street reports.
Developmental psychologists and parents alike have long thought that the cognitive abilities of babies develop in bursts rather than in a predictably linear rate, but the idea been based largely conjecture and anecdote. Now, a new study presents hard data supporting the idea.
A team of researchers lead by psychologist Koraly Perez-Edgar from Pennsylvania State University has published a paper in the journal Child Development demonstrating that babies learn at a non-linear rate.
Their area of examination was the “A-not-B error” – or what is commonly known as object permanence: the point where infants realise that something still exists even if they can’t immediately perceive it. This was first described in 1954 by the pioneering Swiss child developmental psychologist Jean Piaget, who also invented the basic test used in this experiment.
Despite its seeming simplicity, avoiding A-not-B errors is correlated with increased brain activity over multiple sites, measured because improved memory-based tasks correlate with measurable increases in electroencephalograph (EEG) results.
So, the experiment was simple: take a bunch of six-month-olds (28, in this case) and bring them into the lab monthly to perform the Piaget test while having their brain activity mapped using an EEG.
The task the babies performed involved a researcher hiding a toy in one of two wells in a cardboard box set in front of the infant. If the toy was then successfully retrieved by the infant, showing that they remembered that the toy existed and where it was despite not being able to directly see it, the test was considered successful.
“How babies perform in this task tells us a lot about their development because it's a coordination of multiple skills,” explains co-author Leigha MacNeill.
“They have to remember where the ball was moved, which is working memory. They have to know an object exists even though it's out of sight, and they need to track objects moving in space from one place to another. All of this also required them to pay attention. So there's a lot going on.”
The EEG took baseline readings while the babies watched spinning balls in a bingo wheel before measuring brain activity as the babies performed the A-not-B test.
The results mapped neatly as a sigmoid curve: flat at six months, with barely any of the children passing the test, and a gentle curve flattening again at 12 months with most of the children reaching the milestone. The experimenters noted that there was also a lot of variation in development both between the different babies and in individual children over different testing sessions.
In other words, science backs up your intuition. These results indicate that babies learn in punctuated bursts, not at a steady linear rate over time, and the timing of those bursts are as idiosyncratic as the children themselves.