Why We For­get Our Baby Years

Reader's Digest Asia Pacific - - Cover - BY KRISTIN OHLSON FROM AEON.CO

I’M THE YOUNGEST by far of five chil­dren. By the time I started first grade, my sib­lings were gone, and we went from be­ing a very noisy house­hold to a very quiet one.

My fam­ily has told me sto­ries about those early years be­fore my sib­lings left. How my brother am­bushed me around cor­ners with a toy croc­o­dile. How my old­est sis­ter car­ried me like a kan­ga­roo with her joey. But I can of­fer very few sto­ries of my own from that time.

Hardly any adult can. There is a term for this – in­fan­tile ­am­ne­sia, coined by Sig­mund Freud to de­scribe the lack of re­call adults have of their first three or four years and their ­paucity of solid mem­o­ries un­til around age seven. There has been a cen­tury of re­search about whether mem­o­ries of th­ese early years are tucked away in some part of our brains and need only a cue to be ­re­cov­ered. But re­search now sug­gests that the mem­o­ries we form in th­ese early years sim­ply dis­ap­pear.

Psy­chol­o­gist Ca­role Peter­son of Me­mo­rial Univer­sity of New­found­land has con­ducted a se­ries of stud­ies to pin­point the age at which th­ese mem­o­ries van­ish. First, she and her col­leagues as­sem­bled a group of chil­dren be­tween the ages of four and 13 to de­scribe their ear­li­est rec­ol­lec­tions. The chil­dren’s par­ents stood by to ver­ify the mem­o­ries, and even the youngest kids could re­call events from when they were around two years old.

The chil­dren were in­ter­viewed again two years later. Nearly 90 per cent of the mem­o­ries ini­tially of­fered by those ten and older were re­tained. But the younger chil­dren had gone blank. “Even when we prompted them about their ear­lier mem­o­ries, they said, ‘No, that never hap­pened to me,’” Peter­son said. “We were watch­ing child­hood am­ne­sia in ac­tion.”

In both chil­dren and adults, mem­ory is bizarrely se­lec­tive about what ad­heres and what falls away. In one of her pa­pers, Peter­son tells a story about her own son. When he was 20 months old, she had taken him to Greece, where he be­came very ex­cited about some don­keys. They dis­cussed the don­keys for at least a year. But by the time her son went to school, he had com­pletely for­got­ten about them. He was queried when he was a teenager about his ear­li­est child­hood mem­ory. In­stead of the don­keys, he re­called a mo­ment not long af­ter the trip when a woman had given him lots of cook­ies.

Mem­ory is bizarrely se­lec­tive about what ad­heres and what falls away

Peter­son has no idea why he would re­mem­ber that – it was an un­re­mark­able mo­ment that the fam­ily hadn’t re­in­forced with chitchat. To get a han­dle on why some mem­o­ries en­dure over others, she and her col­leagues stud­ied the chil­dren’s mem­o­ries again. They con­cluded that if a mem­ory was very emo­tional, chil­dren were three times more likely to re­tain it. Dense mem­o­ries – in which the kids ­un­der­stood the who, what, when, where and why – were five times more likely to be re­tained than dis­con­nected frag­ments. Still, odd­ball and in­con­se­quen­tial mem­o­ries, such as a bounty of cook­ies, will hang on, frus­trat­ing the per­son who wants a more pen­e­trat­ing look at his or her early past.

To form long-term mem­o­ries, an ar­ray of bi­o­log­i­cal and psy­cho­log­i­cal stars must align. The raw ma­te­ri­als of ­mem­ory – the sights, sounds, smells, tastes and tac­tile sen­sa­tions of ex­pe­ri­ence – ar­rive and reg­is­ter across the cere­bral cor­tex, the seat of cog­ni­tion. For th­ese to be­come mem­ory, they must un­dergo bundling in the hip­pocam­pus, a brain struc­ture lo­cated un­der the cere­bral cor­tex. But some parts of the hip­pocam­pus aren’t fully de­vel­oped un­til ado­les­cence, mak­ing it hard for a child’s brain to com­plete this process.

“So much has to hap­pen bi­o­log­i­cally to store a mem­ory,” psy­chol­o­gist Pa­tri­cia Bauer of Emory Univer­sity told me. There’s “a race to get it sta­bilised and con­sol­i­dated be­fore you for­get it. It’s like mak­ing Jell-O: you mix the stuff up, you put it in a mould, and you put it in the re­frig­er­a­tor to set. But your mould has a tiny hole in it. You just hope your Jell-O – your mem­ory – gets set be­fore it leaks out through that tiny hole.”

In ad­di­tion, young chil­dren have a ten­u­ous grip on chronol­ogy. They don’t have the vo­cab­u­lary to de­scribe an event, so they can’t cre­ate the kind of causal nar­ra­tive that Peter­son found at the root of a solid mem­ory. And they don’t have a great sense of self, which would en­cour­age them to think about their ex­pe­ri­ences as part of a life nar­ra­tive.

Plus, in our early years, we cre­ate a storm of new neu­rons in the ­hip­pocam­pus. A re­cent study in mice sug­gests that this process, called neu­ro­ge­n­e­sis, can ac­tu­ally cre­ate ­for­get­ting by dis­rupt­ing the cir­cuits for ex­ist­ing mem­o­ries. Our mem­o­ries can also be­come dis­torted by other ­peo­ple’s mem­o­ries of the same event or by new in­for­ma­tion.

Mem­o­ries can also be­come dis­torted by other peo­ple’s mem­o­ries of the same event

Of course, some peo­ple have more mem­o­ries from early child­hood than others do. A 2009 study con­ducted by Peter­son, Pro­fes­sor Qi Wang from Cor­nell Univer­sity and Yubo Hou, an as­so­ci­ate pro­fes­sor from Pek­ing Univer­sity, found that chil­dren in China have fewer of th­ese mem­o­ries than chil­dren in Canada do. The find­ing, they sug­gest, might be ex­plained by cul­ture: Chi­nese prize in­di­vid­u­al­ity less than North Amer­i­cans and thus may be less likely to draw at­ten­tion to the mo­ments of an in­di­vid­ual’s life. Western­ers, by con­trast, re­in­force ­rec­ol­lec­tion and keep the synapses that un­der­lie early per­sonal mem­o­ries vi­brant.

When an adult en­gages a child in a lively con­ver­sa­tion about events, invit­ing him or her to add to the story, “that kind of in­ter­ac­tion con­trib­utes to the rich­ness of mem­ory over a long pe­riod of time,” Bauer said. “The child learns how to have mem­o­ries and how to tell the story.”

Our first three to f our yea rs are the mad­den­ingly, mys­te­ri­ously blank open­ing pages to our story of self. Dur­ing that time, we tran­si­tion from what my brother- in- law calls “a loaf of bread with a ner­vous sys­tem” to sen­tient hu­mans. If we can’t re­mem­ber much from those years – whether abuse or ex­u­ber­ant cher­ish­ing – does it mat­ter what ac­tu­ally hap­pened? If a tree fell in the for­est of our early de­vel­op­ment and we didn’t have the cog­ni­tive tools to stash the event in mem­ory, did it still help shape who we are? Bauer says yes. Even if we don’t re­mem­ber early events, they leave an im­print on the way we un­der­stand and feel about our­selves, other peo­ple and the greater world. “You can ’ t re­mem­ber go­ing ice- skat­ing with Un­cle Henry, but you un­der­stand that skat­ing and vis­it­ing rel­a­tives are fun,” Bauer ex­plained. “You have a feel­ing for how nice peo­ple are, how re­li­able they are. You might never be able to pin­point how you learned that, but it’s just some­thing you know.” We aren’t just the sum of our mem­o­ries, or at least not en­tirely. We are also the story we con­struct about our­selves. And that’s a story that we will never for­get.

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