You may vividly remember your grade-school playmates or even the first day at kindergarten. But experiences before your third birthday most likely lie under a mist of oblivion. Researchers now provide evidence that language is the key: Children can only describe memories using words they knew at the time those memories were stored.
Developmental psychologists have puzzled for centuries over why we forget about our earliest childhood experiences, a phenomenon called childhood amnesia. As children's language develops at about the same time, some researchers suspected a possible link between the two developmental milestones.
To test this connection, developmental psychologists Gabrielle Simcock and Harlene Hayne at the University of Otago, New Zealand, exposed children to a unique event at a time when they were barely able to speak. They visited children between 2 and 3 years old at their homes and brought a memorable toy along: the magic shrinking machine. This humongous box featuring handles, knobs, and quirky sounds miraculously shrinks big toys into small ones. After the pull of a lever and turn of a handle, toys such as a teddy bear disappear. Accompanied by flashing lights and bells and whistles, another door opens and a shrunken teddy pops out. On the same visit, Hayne and Simcock carefully tested the toddlers' vocabulary.
One year later, the psychologists visited the kids again to test their memories for the magic shrinking machine, before showing them the machine again. To their surprise, the children described the box exclusively with words that were already part of their vocabulary a year earlier, the researchers report in the May issue of Psychological Science. The kids were unable to use newly acquired words that were by now part of their everyday vocabulary. Their verbal descriptions of the event were frozen in time, Hayne says. Nonetheless, once placed in front of a magic shrinking box, the kids still knew which sequence of actions to take to shrink a toy. They also accurately recognized photographs of toys they had played with. The researchers conclude that the children cannot translate memories into language if the words weren't available when the memories were created.
Developmental psychologist Andrew Meltzoff of the University of Washington, Seattle, is intrigued by the idea that the human mind starts off first with a nonverbal code to store memories that later transforms into a language-based code. "The study demonstrates that once you are thinking in language, you can't reach back to the nonverbally coded memories and describe it with words," Meltzoff says.