YOUR MEMORIES
As well as being creative and constructive, many of our memories are
also dynamic, a phenomenon psychologists have dubbed “representa-
tional momentum”. Imagine you see a photograph of a man falling from
a tall building. Research has shown that your memory of this picture
will evolve in the direction of the implied motion, as if playing out the
man’s fate in your mind. Because of this, if I showed you a second picture
with the man slightly further along the trajectory of his fall and asked
you whether the photo was the same or different from the first, you’d be
likely to mistakenly say that it was the same picture. By contrast you’d be
far less likely to make this error if I showed you a comparison picture
of the man higher up, earlier in his trajectory. A neat study by psycholo-
gist Carl Senior showed that representational momentum is stopped or
reduced when a magnet is used to temporarily disrupt the part of the
visual brain that usually processes movement, thus demonstrating the
ongoing links between memory and sensory processing.
Related to representational momentum is a phenomenon known
as “boundary extension”. This is the way that our memory for a scene
expands beyond its original border. Imagine you’ve just looked at a scene
in a holiday snap. You might think that your memory for the scene will stay
faithful to the edges of the photo, but in fact your memory spills out over
the edges, effectively expanding the scene beyond its original borders. This
effect may sound odd, but it probably occurs as a result of the fact that our
vision is only high acuity in the centre of our gaze. Although we actually
Glance at this photo, then take a quick look at the photo overleaf.