New Study Reveals Why We Struggle To Recall Childhood Memories

A new study published in the journal Science explores why humans, despite forming memories in infancy, struggle to recall them later in life. Using functional Magnetic Resonance Imaging (fMRI) on awake infants engaged in a memory task, researchers uncovered that while infants can encode memories early on, the inability to retrieve these memories stems from underdeveloped retrieval systems.

Despite infancy being a period of rapid learning, memories from this time, do not persist into later childhood or adulthood. Most humans cannot recall what they were doing till the age of three and the study aims to shed light on the long-standing mystery.  

The findings suggest that infantile amnesia -- the phenomenon where early childhood experiences fade from recollection—may be driven more by retrieval failures than an absence of initial memory formation.

"The availability of encoding mechanisms for episodic memory during a period of human life that is later lost from our autobiographical record implies that postencoding mechanisms, whereby memories from infancy become inaccessible for retrieval, may be more responsible for infantile amnesia," the study highlighted.

A total of 26 infants participated in the study with half under a year old and half over. The major challenge for researchers was getting the babies to act still in the fMRI machine since they are notorious for being uncooperative.

Nick Turk-Browne, professor of psychology at Yale and the study's senior author, told Science Alert that his colleagues used methods refined over the years, to ensure that they got as still images as possible. They worked with the families to incorporate pacifiers, blankets, and stuffed animals; holding babies still with pillows; and using psychedelic background patterns to keep them engaged.

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Though there were blurry images during the process, the team managed to overcome the hurdle by running hundreds of sessions. Afterward, the researchers compared brain activity during successful memory formation versus forgotten images and found that the hippocampus is active in memory encoding from a young age.

Notably, the hippocampus is a part of the brain, critical for episodic memory, which is not fully developed in infancy. The study showed that babies who performed best on memory tasks showed greater hippocampal activity.

"What we can conclude accurately from our study is that infants have the capacity to encode episodic memories in the hippocampus starting around one year of age," said Mr Turk-Browne.

Scientists are now conducting another study to test whether infants, toddlers, and children can recognise video clips recorded from their own perspective as young babies.