Memory fuels our fears
Humans have a six-hour window of opportunity when fearful memories can potentially be erased, a study says.
Reliving a harrowing memory opens what experts call a "reconsolidation window" - a time-limited period when it can be changed from bad to good.
A New York University team was able effectively to neutralise fearful memories by acting within six hours.
They hope their work, reported in Nature, will ultimately help those with disorders like post-traumatic stress.
In the study, the volunteers were wired up to electrodes and given a shock each time they were shown a picture of differently coloured squares to make them fearful of the image - which they did.
A day later, the investigators worked on banishing the fear.
They re-exposed the volunteers to the same image, but this time without the shocks.
They found that this worked, but only if the volunteer was first made to recall the fearful experience and, critically, made to recall it no longer than six hours before the "treatment" commenced.
Also, the treatment only blocked fear for the specific coloured square for which the fear memory was recalled, suggesting that the erasure is highly specific.
Lead researcher Dr Elizabeth Phelps of New York University said: "Timing may have a more important role in the control of fear than previously appreciated.
"Our memory reflects our last retrieval of it rather than an exact account of the original event.
"Our results suggest a non-pharmacological, naturalistic approach to more effectively manage emotional memories."
Professor Anke Ehlers, an expert in post traumatic stress disorder at London's Institute of Psychiatry, said: "Talking about the traumatic memory can help. That's a common element of therapies.
"People need to realise it is the memory that is fearful and not the current reality."