and sweating, it appeared that those previously given propranolol were
far less traumatized by hearing their memories than those who’d just
been given an inert placebo pill. The participants given propranolol
could still remember their traumatic experience, but seemed less
disturbed by it.
An obvious shortcoming of these studies is that they required partici-
pants to take drugs. However, late in 2009, psychologists showed that
fearful memories could be wiped clean using a drug-free technique. At
New York University, Elizabeth Phelps and her co-workers first trained
participants to fear a coloured square by repeatedly pairing it with a
mild but unpleasant electric shock. A standard therapeutic approach
to removing this fear, known as “extinction”, would involve exposing
participants to the coloured square without the shock, in order to teach
them that there is no longer any reason to fear the square. Phelps’s
team adopted this approach, but also applied the animal research that
showed how memories are susceptible to modification just after they’ve
been recalled. Phelps’s team showed that the extinction therapy was
significantly more effective when it was delivered just ten minutes after
participants were given a reminder of the square, compared with six
hours later or after no reminder at all. It’s as if the reminder had tempo-
rarily rendered the “square-shock” memory particularly fragile, so that it
was completely written over by the harmless experiences of the square
without the shock.
All this sounds hopeful, but it’s worth mentioning that some commen-
tators have raised ethical concerns about the prospect of traumatic
memory eradication. It’s easy to understand their concerns. For example,
what if the techniques were exploited to modify the memory of a witness
to a crime? One defence is that the current approaches haven’t actually
been shown to eradicate memories, but rather to reduce their emotional
salience. That still leaves some moral questions. For example, if drugs
were developed that could strip a memory of its meaning, then what’s
to say people wouldn’t start popping pills to clear their conscience? And
without the guiding influence of guilt and regret, who knows how people
might start behaving?
Déjà vu
Déjà vu is the term used for the unnerving sensation of experiencing a
new situation as if it had happened before, the eerie feeling that you’re
retreading the path of an earlier existence. About two thirds of us
YOUR MEMORIES