From Experience to Memory

Our knowledge of the world grows rapidly in the first few years of life, but our memories of that time are few and far between. How does this fit together—and what does it reveal about the architecture of human memory?
 

Memory is complex—especially when it comes to our own childhood. A few memories appear fairly vivid; others are blurry and fragmented. And many things we believe we remember may actually come from photos or from stories told to us later about our own past. Zoe Ngo leads the Emmy Noether Group RAVEN | Realworld Applications of Variability in Episodic memory and Neurodevelopment. Her curiosity about the differing quality of her own childhood memories turned into a scientific question: How does memory develop in children?

At the heart of this question is a striking paradox: In the first years of life, children recognize patterns, learn social routines, and build up knowledge about their environment. Yet surprisingly few childhood experiences remain accessible later in life. How do young children acquire so much knowledge when memories of individual events seem fleeting?

A key to understanding this paradox lies in the different forms and functions of memory: Episodic memory enables us to recall specific events—what happened, where, and when. Semantic memory, by contrast, stores general knowledge about the world and allows us to generalize from experience. These two systems do not develop at the same pace in early childhood: Semantic memory and generalization abilities appear to develop earlier than episodic memory. "In early childhood, the priority may be on learning regularities from the environment, because this creates a useful foundation on which more detailed memories of specific events can later be stored long-term," Ngo says.

Ngo's studies focus on children between the ages of 3 and 10 years. "The age of 6 to 7 years is considered a turning point in the development of episodic memory," she explains. Before that, children are not yet reliably able to retain individual experiences over longer periods and later recount them; after it, they increasingly approach adult-like performance in some tasks. By assessing children aged 3 to 10 years, the team can trace how profiles of memory abilities develop before and after this turning point.

The RAVEN team uses several approaches to examine these changes. Part of the research consists of labbased memory tasks designed to test specific memory processes—for example, whether children remember what happened, where an event took place, and when it occurred, or whether they can distinguish between similar experiences.

The team also studies how memories of real-life events develop. In selected everyday situations, children wear small wearable cameras that take photos at fixed intervals. Families choose which events to document—a birthday, a museum visit, or a day out, for instance. From these image sequences, the research team then develops individualized memory tests: Children view pictures from their own lives and report what they remember.

In a further step, the researchers examine what happens in the brain during this process. During a magnetic resonance imaging (MRI) scan, children view both images from their own camera and images from other children’s cameras. This allows the team to distinguish between patterns of brain activity associated with successful versus unsuccessful retrieval of personal memories.

Crucially, the researchers follow the same children over several years. Children enter the study at ages 3 and 5 years, and are assessed repeatedly over a period of about 5 years. These long-term observations reveal that memory does not develop uniformly among children of the same age. The team’s goal is to understand these individual differences.

The research also considers the conditions under which children have experiences. Memory development does not take place in a vacuum, Ngo emphasizes. Family, school, and the broader social environment influence what children pay attention to, how often they recount events—and, in turn, what they remember later.

To better understand how environmental factors shape memory, Ngo’s group collaborates with international partners. RAVEN is part of the LEVANTE research network initiated by the Jacobs Foundation. Several research teams across different continents are using comparable methods to collect data on the development of learning and memory.

For Ngo, it is conceivable that learning environments could one day be tailored more closely to individual memory profiles. For this to become possible, however, research must first show, over long periods, how different memory profiles develop and how they relate to learning outcomes. Only then can strategies be developed together with educators and policymakers to translate these insights into practical educational approaches. This remains a long-term vision—but it shows where this line of research could ultimately lead.