Why do we forget our childhood? Maybe we don’t:
Gabrielle Simcock and Harlene Hayne of the University of Otago noticed that the period of amnesia tends to end at about the time of the onset of language, so they devised an experiment to test whether language ability might be at the root of the problem (‘Breaking the Barrier? Children Fail to Translate Their Preverbal Memories Into Language,’ Psychological Science, 2002).They created a memorable event for toddlers of ages ranging from two to three: a magical shrinking machine. The experimenter taught the children how to use the large apparatus — a black box with impressive shiny cranks and handles — to “shrink” a set of toys. The toys were placed in a large hole in the top of the box, and after the appropriate sequence of crank-spinning and button-pushing, a smaller replica of the toy appeared in a separate part of the machine. At the same time, the toddlers were given a verbal ability test. And critically, their parents were asked which words from the magical shrinking machine demonstration their children could actually say.
Six months to a year later, the toddlers were revisited and asked about the experience. Most kids, regardless of their age, could say very little about the shrinking machine. However, when they were shown photos of the toys from the experiment along with decoys (for example, four teddy bears, only one of which was used in the game), they accurately identified the toys from the game most of the time. The identical language tests were given to the children at this point, and by this time the children knew nearly all of the words used in the original experiment. Yet none of the children interviewed used any of the words that they did not know at the time of the original demonstration to describe their memory of the event. Though they clearly could remember the experience, and even showed the experimenters how the machine worked, they didn’t use the proper words for the parts of the machine (”handle,” “knob”) if they hadn’t known them at the time of the original event. The memory existed, but the words were not associated with the memory.
Simcock and Hayne argue that these memories simply are not ever encoded in language, and for that reason, never become part of an adult’s autobiographical memory.