Amy Morrison recently made a discovery during her 6-month-old baby's bathtime. "I stood Avery up against the tub to dry her off, and she pushed a plastic bottle of soap into the water," reports Morrison, who lives in Easton, Pennsylvania. "The bottle made a big splash, and she just started cracking up." Morrison fished the bottle out of the water several times and placed it on the edge of the tub. Each time, Avery repeated the action and made herself laugh.
But the real surprise came a week later, when Avery's father returned from a business trip. Morrison wondered whether their daughter would repeat the same trick for him, so she deliberately set the bottle of soap on the tub's edge. "Avery started giggling as she pushed the bottle into the water," Morrison marvels. "That made me wonder whether she actually remembered doing it the last time, or whether she was discovering it again."
Memories become more complex as baby's brain develops
Research has taught us a lot about memory in the past few decades. One of the key findings is that humans don't use only one memory system, but several. The first to develop is procedural memory, which we rely on for basic motor skills like rolling over, using a spoon, riding a bike -- or knocking a bottle into the bathtub because it makes a funny splash.
As your baby's brain develops and he becomes more aware of the world around him, he'll begin to have a semantic memory, too, which researchers define as knowledge about the world that extends beyond our bodies. Semantic memory allows us to make simple associations. "These are the things we feel like we intuitively just know," explains Stephen Christman, PhD, a memory researcher at the University of Toledo, Ohio.
For a baby, that might mean knowing things like what applesauce looks like or that the stove could be hot. As he grows, his semantic memory will expand to include things like a green light means go, or a knock on the door signals that there are visitors.
As recently as a decade ago, researchers assumed that an infant's brain was too undeveloped to remember much more than these simple motor responses and associations for the first year of life. However, current memory studies reveal that babies are able to remember relatively complex pieces of information at a young age. What's more, your baby's memories can last for a long time, especially if you help him to strengthen them.
For instance, Carolyn Rovee-Collier of Rutgers University in New Jersey has demonstrated that 3-month-olds who see a sequence of actions modeled on a hand puppet -- like having a mitten removed -- can imitate those actions at 6 months of age when they develop the motor skills to perform them.
The key is that they need to be given reminders in between, like seeing the puppet for 60 seconds every three weeks. But with the right cues, "babies can remember something they learn at 6 months for up to two years," she says. While these findings may not seem all that relevant to a baby's day-to-day life (taking a mitten off of a puppet isn't a skill she'll use very often!), they show that visual cues can boost a baby's memory -- and also help her to navigate her surroundings.
For instance, when her daughter Meg was 8 months old, Virginia Smith of Brookline, Massachusetts, noticed that "whenever I walked her stroller in one direction, Meg would kick her legs, wave her arms, and act really excited." However, if they walked in the opposite direction, she howled in protest. What was going on? Smith had no idea, until Meg's babysitter explained that she often took the baby to a park in that "exciting" direction. The various landmarks on the way reminded Meg of where they were going -- and she knew that one direction meant fun.
My Memory, Myself
Not only does memory help us make sense of the world, it also helps us make sense of ourselves. The ability to recall what happened forms a large part of our identity because our past experiences are what we draw on to learn new things, and what ultimately make each of us unique.
No one really knows when autobiographical memories begin. But by age 1, your baby will remember certain past events in his own life even without cues -- long before he has the language ability to describe those memories. I discovered this for myself when I took my son Aidan, then 4, to the city library for a book I couldn't find locally. On our way, I told him where we were going. "Oh yeah, I remember that place," Aidan said.
"I don't think so," I answered, since Aidan wasn't yet 2 the last time we'd made the trip.
"But I do," he insisted. "The library has big stairs, plants around a fountain in the middle of the floor, and a rug the color of skin."
Well, guess what? That library does have a rug the color of skin. And big stairs. And a fountain in the middle, surrounded by ferns. Aidan had indeed remembered it, even though he hadn't been in the building for two years and couldn't say more than a few words the last time he saw it.
According to memory researcher Robyn Fivush, PhD, of Emory University in Atlanta, most toddlers are able to recall past events, especially if those events are special, like trips to theme parks or other distinctive places. It's only because their language is limited that we don't know what they're remembering. She believes that babies develop a sense of past versus present time somewhere between ages 1 and 2; for instance, when she quizzed a group of 3-year-olds about trips they'd taken to Disney World when they were 18 months old, she discovered that "their memories were surprisingly accurate, corresponding well to what their parents also remembered."
Of course, what most parents want to know is what their children will remember as adults. This year, for example, Georgia Epstein of Newbury, Massachusetts, is planning to take her daughters, ages 2 and 5, on a road trip through the Southwest. "I want to do all I can to give my children happy memories of their childhood," she says.
Can we make good memories stick in the first years, when research indicates that the earliest memories adults hold on to only date back to age 3 or 4? According to experts, the answer is a maddeningly complex "yes and no."
Memories of Babyhood?
Infantile amnesia -- the phrase scientists use to describe the fact that humans can rarely access memories of events that happened before age 3 or 4 -- is still a mystery, but it's definitely a fact of life. If you took those same children in Fivush's study who, at age 3, could remember the Disney World trip they took at 18 months, and asked them about that trip again at age 20, "they probably wouldn't remember much," says David Sobel, PhD, of Brown University in Rhode Island. Why?
Perhaps, says Sobel, our emerging ability to use language forces us to encode and reorganize our memories differently by age 4 than we did as babies. At any rate, nobody knows yet whether our earliest preverbal memories are wiped out or merely covered up.
"The bottom line is that there are lots of areas of the brain that aren't fully developed at birth," says Sobel. "It might just be that, by age 3 or 4, we experience such an overload of information that something's got to go."
At the same time, even if your baby won't retain specific memories of a family trip to visit her grandparents or the elaborate princess cake you baked for her second birthday party, she will recall an overall sense of warmth and love when she thinks back on her childhood. And if you talk about these experiences, she's more likely to remember them. In essence, parents who reminisce in more detail with their children, and who include details that put the events into context, "have children who are better able to recall their past experiences in detailed, coherent narratives," says Fivush.
In addition, talking about past experiences "creates a shared life together that helps your child know who she is. And as she develops a sense of her past, she will also develop a sense of her possibilities in the future," says Fivush.
Do Lefties Have Better Memories?
In one surprising recent study aimed at making sense of human brain and memory development, Stephen Christman, PhD of the University of Toledo, Ohio, looked at memory as a function of right- and left-handedness.
When he asked right- and left-handed college students about their earliest memories, he discovered a marked difference: "The earliest memory for left-handers was age 3 years and 11 months, almost a year earlier than right-handers, who couldn't recall much before age 4 years and 7 months."
Why should left-handers have this edge? Simply put, they use both sides of their brain more equally. Brain-activity tests demonstrate that the corpus callosum (the area of the brain where messages get transmitted back and forth between the right and left sides) of the average left-handed person is 15 percent larger than in the average right-hander. That's because left-handed folks have bigger bundles of mediating fibers passing messages back and forth.
Our memories aren't stored in any one location in the brain. Rather, they are distributed throughout the brain and maintained by complex brain-cell connections. "The basic relation between memory and the two sides of the brain is that semantic memories are encoded and retrieved by the left hemisphere alone," explains Christman. "Recalling episodic, autobiographical memories requires interaction between the left- and right-brain hemispheres."
Holly Robinson, a mother of three, is a writer outside of Boston.
Originally published in American Baby magazine, August 2004.
All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.