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Forgetting helps children understand how to use symbols

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Dr. Kelly Sheehan, Alum of Northwestern University

Kelly Sheehan and researchers set out to observe how children can best understand what a symbol is and how to use it. Prior research found a developmental difference in 2 year-olds and 3 year-olds but did not specify the role of forgetting in symbolic representation. In Sheehan’s study, casually referred to as the duck study,  children were asked to find a toy duck hidden in a large room using a scaled-version of the room and duck to determine the location of the hidden duck. The researchers observed how well children were able to use the scaled-model as a symbol of the larger room. Once children understand the physical similarity of the two rooms and how to use the symbol, all that remains is a simple spatial problem of locating the character “under” a sofa cushion or “inside” a bucket.

Forgetting has been shown to be important for helping adults gain insight into a problem, so the researchers hypothesized that giving children a break may promote insight into a symbolic problem. The researchers separated the effects of forgetting from children’s use of the symbol by introducing a delay midway through the test trials.  Sheehan noted, “We were surprised to find that children were better at using a scale model as a symbol after a 24-hour delay. It seemed conceivable that children would actually do worse after the break because they forgot what they learned about how to use the model over the delay. Instead, we found that the delay was instrumental in helping children grasp the symbolic nature between the model and the larger room it represented.”

Fig.1 (Sheehan, 2019)                                                                                Children were asked to use this scaled-model of a larger room to play a simple spatial game.

The researchers modeled children’s performance before and after a 24-hour delay using a mixed-effects logistic regression. They found the delay helped children forget misleading information such as where they had previously searched, which they could confuse with the location of the duck shown earlier to them. Children also had time to distance themselves from the attractiveness of the scale-model as an object and focus on appreciating its symbolic nature. The researchers suggest the 24-hour delay helped children learn to use the model by giving them an opportunity to forget what was unimportant.

These results have great implications about symbolic development and cognitive development. “If a break can promote insight for children who are on the verge of understanding the relation between a symbol and its referent, then a break might be critical for children gaining insight into other types of relations that promote learning” explains Sheehan.

Dr. Kelly Sheehan  received her Ph.D. from Northwestern University in Cognitive Psychology and completed a 2-year Postdoctoral Fellowship at the Center on Media and Human Development. Her research centered on how children learn from symbols which includes how they learn STEM concepts from media. She is currently a User Researcher at an educational technology company, Age of Learning, where she conducts research with children, parents, and teachers, and aims to understand how to best design digital products that promote learning. She also enjoys sharing research more broadly and has written for Parenting for a Digital Future,, and authors her own blog, Baby to Brainy.

The abstract to the paper, “Forgetting and symbolic insight: Delay improves children’s use of a novel symbol” is publicly available at:



Works Cited:

K. J. Sheehan, B. Ferguson, C. Msall et al., Forgetting and symbolic insight: Delay improves children’s use of a novel symbol, Journal of Experimental Child Psychology,