Fascinating study – but be careful – the brain connects lessons learned differently as we get older

Does the memory of children work in a different way than the memory of adults? This new study suggests it does. I do think that the hopes for more personalized learning mentioned in the press release, are way off. The actual study is interesting enough, as Margaret L. Schlichting and colleagues describe:

The ability to make decisions that span multiple memories is a critical component of behavioural flexibility. In children, this ability is related to academic achievement, underscoring that the importance of understanding developmental change in this mechanism goes well beyond the lab. Here, we provide neural support for previous suggestions that children do not store memories with respect to their shared content, and we extend this framework into an understudied period of memory development to uncover an adolescent-specific neural phenomenon. Our results directly linking memory operations to the later ability to reason about those memories represent an important step towards bridging these literatures. More directly, these data suggest that child, adolescent and adult learners may rely on different mechanisms to achieve maximal behavioural flexibility—an idea that might be tested in future research and educational settings.

What does this mean? The press release summarizes:

To understand the distinction between how adults and children make inferences, imagine visiting a day care center. In the morning, you see a child arriving with one adult, but in the afternoon that child leaves with a different adult. You might infer that the two grown-ups are the child’s parents and are a couple, and your second memory would include both the second person you saw and information from your earlier experience in order to make an inference about how the two adults — whom you didn’t actually see together — might relate to each other.

This new study finds that a child who has the same experiences isn’t likely to make the same kind of inference that an adult would during the second experience. The two memories are less connected. If you ask your child to infer who that child’s parents are, your child can still do it; he or she just has to retrieve the two distinct memories and then reason about how each adult might be related.

The neural machinery of children and adults differs, and the strategy that children use may be optimal for the way their brains are wired before key memory systems in the hippocampus and prefrontal cortex fully mature, the researchers believe. That difference could keep children from recalling past memories during new learning and limit their ability to connect events.

“In the absence of a mature memory system, the best thing a child can do is lay down accurate, non-overlapping memory traces,” Preston said. “From those accurate memory traces, children can later bring them to mind to promote inferences about their connections.”

The researchers asked 87 subjects, ages 7 to 30, to look at pairs of images while lying in an fMRI (functional magnetic resonance imaging) scanner, which measures brain activity by detecting small changes in blood flow with images that, as in the day care example above, provide opportunities to infer relationships between objects that had not appeared together.

The researchers found that the strategy adolescents used for making inferences was different from both that of young children and adults. Going back to the example of the parents at the day care, when an adolescent stores a memory of the second grown-up with the child, the adolescent suppresses the earlier memory involving the first one. Each memory becomes even more distinct than with younger children, and there are even fewer automatic inferences about how the two adults relate.

“Teenagers may have learning strategies that are tuned to explore the world more so than exploiting what they already know,” Preston said.

This conclusion sums it up:

We show that developmental differences in memory mechanisms influence how individuals of different ages make inferences about related episodes. Notably, we found that early adolescence was a unique period marked by initial reinstatement of memories during learning followed by later suppression—a signature consistent with differentiation of overlapping memories at this point in development. In contrast, adults showed enhanced reactivation consistent with integration at encoding, while children showed no significant evidence of reactivating at all and may store memories separately. These different memory mechanisms conferred age-specific behavioural advantages for inference: while suppressing reactivation benefitted those at the younger ages, enhancement was associated with correct inferences among adults. Interestingly, these differences emerged despite all participants being fully aware of the task structure and upcoming inference, thereby reducing the possibility that age-related differences in detecting overlap would be driving our effects.

And of course, there are remaining questions:

However, one limitation is that we did not assess the influence of overt strategy in this task; as such, whether younger learners can engage an integration mechanism when explicitly instructed to do so—or whether, as we would predict, their neural system acts as a fundamental limitation on this ability—remains an open question.

Abstract of the study:

Despite the fact that children can draw on their memories to make novel inferences, it is unknown whether they do so through the same neural mechanisms as adults. We measured memory reinstatement as participants aged 7–30 years learned new, related information. While adults brought memories to mind throughout learning, adolescents did so only transiently, and children not at all. Analysis of trial-wise variability in reactivation showed that discrepant neural mechanisms—and in particular, what we interpret as suppression of interfering memories during learning in early adolescence—are nevertheless beneficial for later inference at each developmental stage. These results suggest that while adults build integrated memories well-suited to informing inference directly, children and adolescents instead must rely on separate memories to be individually referenced at the time of inference decisions.

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