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FAQ. Can you choose
what to forget?
WHY CAN’T WE REMEMBER
BEING BABIES?
E ALL have memories we would
rather forget – and it is possible,
W if you try hard enough.
It is easy to think of memories as
something you can actively strengthen,
whereas forgetting is a passive process.
Infants are constantly learning, but only But we have started to discover it can TARA MOORE/GETTY
a handful of people have memories from be intentional too.
before the age of 2. That’s because Perhaps the easiest way to forget
parts of the brain critical for longer-term something is simply to try to suppress a
memory are still immature. So babies can memory. Jeremy Manning at Dartmouth Given the vital role of sleep in memory
form memories – a 6-month-old can recall College, New Hampshire, has found that formation (see “What happens to your
how to do certain tasks for up to three just telling people to “push thoughts out of memories when you sleep?”, page 34),
weeks – but holding onto them is tricky. their head” is enough to make them forget this is also a prime time to intercept them.
As the brain begins to mature, that lists of words they have learned to associate Earlier this year, Katharine Simon at the
neural machinery gets more efficient and with particular cues. “We don’t know how, University of Arizona and her colleagues
memories start to stick – until the age of 7, but people seem to know how to do it.” found that they could train people to
when there’s a sudden dip. Children recall This seems especially paradoxical associate a particular sound with the
far more about earlier events in their lives because we also know that rehearsing instruction to forget something. They
when asked before they are 7 than just memories helps to strengthen them. then taught the volunteers to associate
a year later. This sudden erasure, known Suppression has been linked to decreased other sounds with specific words.
as “childhood amnesia” may be down to activity in the hippocampus, so we may be Then, as the volunteers slept, the
pruning, the brain’s process of snipping unknowingly reducing our hippocampal team reactivated the memories of some
away lesser-used connections to activity by focusing on the present, says of these words using their associated
strengthen those that remain. Justin Hulbert at Bard College, New York. sounds, while also playing the “forget”
Although the slightly older children This won’t work for everyone. Post- sound. A week later, the volunteers were
remember fewer things, their recollections traumatic stress disorder (PTSD) involves worse at remembering these words than
are more detailed. “What’s also developing intrusive memories that keep coming words that hadn’t been targeted.
is your ability to tell a good story,” says back – often suddenly and unexpectedly. Being able to exert some control over
Patricia Bauer at Emory University in Studies have found that people with what you remember probably helps to
Atlanta, Georgia. “You place it in context, this condition are less able to suppress bolster your resilience in the face of
you tell me what you did, highlight certain memories, even those unrelated to adversity, says Hulbert.
events and activity. All of those things traumatic incidents. Beware the downsides, however.
are part of what we mean by But other approaches for forgetting Hulbert’s team found that when you try to
autobiographical memory.” might help, including what are known as suppress a memory, you are later less likely
This points to a possible strategy cognitive vaccines: interventions that to remember things that happened around
for hanging onto more of those early can “inoculate” the brain against the onset the time you attempted suppression.
memories, or at least attempting to of PTSD symptoms if administered soon It seems that quietening your hippocampus
influence which ones stick. In cultures after trauma. to block a memory causes an “amnesic
where family storytelling is a cherished Some computer games seem to do the shadow” that more generally impairs
pastime, people are more likely to retain trick. Playing Tetris after watching an memory formation.
early childhood memories. Summoning upsetting film has been found to reduce And good can come from holding on
and reviewing these memories, flashbacks of that film, possibly because to even the most awkward of memories,
a process known as reconsolidation, thinking about a visual task stopped the Hulbert says. “For sure, bringing one to
can fortify them. brain from processing the visual images mind can be cringe-inducing, but it’s
So if you want your child to remember of death and injury from the film. However, important to reflect on the good that
a special trip to the beach, indulge in a little doing a non-visual task, such as playing certain embarrassing memories can bring,
reminiscing, and get them to tell you the a general knowledge game, actually as learning experiences that teach us what
story. Tiffany O’Callaghan increases flashbacks. not to do again.” Penny Sarchet
27 October 2018 | NewScientist | 35
