Baltimore, MD, USA. There is enduring interest in how infants and young children perceive themselves and their surrounding world, then perform complex reasoning tasks to make sense of it all (or at least the high-priority portions). Those born with Harry Benjamin Syndrome (HBS) well know of this, but often face doubts about their veracity.

 

Let's try a test of your memory. Which is easier to remember: 4432879960 or 443-297-9960? The latter, of course. Adults seem to know automatically, in fact, that long strings of numbers are more easily recalled when divided into smaller "bite-sized chunks," which is why we break up our telephone and Social Security numbers in this way.

 

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Conceptual knowledge increases infants' memory capacity. Lisa Feigenson and Justin Halberda. PNAS EE 14 July 2008. doi: 10.1073 / pnas.0709884105  [ Download PDF ]

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Now researchers at The Johns Hopkins University have discovered that children as young as 14 months old can — and do — use the same technique to increase their working memories, indicating that "chunking" information in this way is not a learned strategy, but is, instead, a fundamental aspect of the human mind.

 

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Lisa Feigenson and Justin Halberda, assistant professors of psychological and brain sciences at The Johns Hopkins University. Photos courtesy of Will Kirk at Johns Hopkins.

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"Our work offers evidence of memory expansion based on conceptual knowledge in untrained, preverbal subjects," said Feigenson.

 

"What we have basically done is show that very young children, who can usually only keep track of about three objects at once, can keep track of more if they use the kind of conceptual, linguistic, perceptual and spatial cues adults also use."

 

The research findings appear in the Proceedings of the National Academy of Sciences (PNAS).

 

Lisa Feigenson works out of the Hopkins Laboratory For Child Develoment on issues of broad relevance to cognitive psychology. A central focus is to determine the mental representations that store information and find out what computations can be performed over those representations.

 

The study of infants and young children is important, Feigenson says, because infant performance can provide information on the cognitive primitives available throughout the human lifespan and their evolutionary significance. Moreover, studying children enables observation of changes in the representational vocabulary.

 

Investigators examine key points in development to understand the the role played by a set of representations as new knowledge is acquired and knowledge structures are created.

 

In the team's current experiment, the 14-month-olds were shown four toys which were then hidden in a box. The children then were allowed to search for the missing toys. Sometimes, two of the four toys were secretly withheld in another place. The researchers observed how long the youngsters continued to search the box, the idea being that they would search longer if they remembered there were more toys yet to be found.

 

The researchers found the children would search longer when the four toys consisted of two groups of two familiar objects, cats and cars, and one of each type had been withheld. That indicated that the youngsters were using mental chunking as a way to recall more items at a time. 

 

The team also found that 14-month-olds can use spatial grouping cues (the researchers grouped six identical orange balls in three groups of two before hiding them) to expand memory, in the same way that adults group digits when remembering phone numbers. When provided with such cues, the little ones could remember up to six objects.

 

These results suggest that memory is not merely a passive storage system that makes a "carbon copy" of our experiences. Instead, Feigenson says, the results show that from at least early toddlerhood onward, memory is constantly being restructured and reorganized to maximize its efficiency.

 

The researchers' results may have implications for educational strategies or for helping those who suffer short-term memory problems. But more directly, they show that the memory systems of young infants are surprisingly similar to those of adults.

 

This research was supported by the US National Institute of Child Health and Human Development (NICHD) and a Scholar Award from the James S. McDonnell Foundation.

 

Conceptual knowledge increases infants' memory capacity. Lisa Feigenson and Justin Halberda. PNAS EE 14 July 2008. doi: 10.1073 / pnas.0709884105  [ Download PDF ]

Abstract

Adults can expand their limited working memory capacity by using stored conceptual knowledge to chunk items into interrelated units. For example, adults are better at remembering the letter string PBSBBCCNN after parsing it into three smaller units: the television acronyms PBS, BBC, and CNN. Is this chunking a learned strategy acquired through instruction? We explored the origins of this ability by asking whether untrained infants can use conceptual knowledge to increase memory. In the absence of any grouping cues, 14-month-old infants can track only three hidden objects at once, demonstrating the standard limit of working memory. In four experiments we show that infants can surpass this limit when given perceptual, conceptual, linguistic, or spatial cues to parse larger arrays into smaller units that are more efficiently stored in memory. This work offers evidence of memory expansion based on conceptual knowledge in untrained, preverbal subjects. Our findings demonstrate that without instruction, and in the absence of robust language, a fundamental memory computation is available throughout the lifespan, years before the development of explicit metamemorial strategies.

 

chunking, development, object, hierarchical

 

Lisa Feigenson and Justin Halberda, assistant professors of psychological and brain sciences at The Johns Hopkins University. Photo courtesy of Will Kirk at Johns Hopkins.

 

Caption: Lisa Feigenson, assistant professor of psychological and brain sciences at The Johns Hopkins University.

, in the Child Development Laboratory

 

Credit: Photo courtesy of Will Kirk at at The Johns Hopkins University.

 

 

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