Your Memory Is Like
the Telephone Game, Altered With Each Retelling
 |
| Remember the telephone game where people take turns whispering a message into the ear of the next person in line? By the time the last person speaks it out loud, the message has radically changed. It's been altered with each retelling. Turns out your memory is a lot like the telephone game, according to a new Northwestern Medicine study. (Credit: © Minerva Studio / Fotolia) |
Remember
the telephone game where people take turns whispering a message into the ear of
the next person in line? By the time the last person speaks it out loud, the
message has radically changed. It's been altered with each retelling.
Turns
out your memory is a lot like the telephone game, according to a new
Northwestern Medicine study.
Every
time you remember an event from the past, your brain networks change in ways
that can alter the later recall of the event. Thus, the next time you remember
it, you might recall not the original event but what you remembered the
previous time. The Northwestern study is the first to show this.
"A
memory is not simply an image produced by time traveling back to the original
event -- it can be an image that is somewhat distorted because of the prior
times you remembered it," said Donna Bridge, a postdoctoral fellow at
Northwestern University Feinberg School of Medicine and lead author of the
paper on the study recently published in the Journal of Neuroscience.
"Your memory of an event can grow less precise even to the point of being
totally false with each retrieval."
Bridge
did the research while she was a doctoral student in lab of Ken Paller, a
professor of psychology at Northwestern in the Weinberg College of Arts and
Sciences.
The
findings have implications for witnesses giving testimony in criminal trials,
Bridge noted.
"Maybe
a witness remembers something fairly accurately the first time because his
memories aren't that distorted," she said. "After that it keeps going
downhill."
The
published study reports on Bridge's work with 12 participants, but she has run
several variations of the study with a total of 70 people. "Every single
person has shown this effect," she said. "It's really huge."
"When
someone tells me they are sure they remember exactly the way something
happened, I just laugh," Bridge said.
The
reason for the distortion, Bridge said, is the fact that human memories are
always adapting.
"Memories
aren't static," she noted. "If you remember something in the context
of a new environment and time, or if you are even in a different mood, your
memories might integrate the new information."
For
the study, people were asked to recall the location of objects on a grid in
three sessions over three consecutive days. On the first day during a two-hour
session, participants learned a series of 180 unique object-location
associations on a computer screen.
The next day in session two, participants
were given a recall test in which they viewed a subset of those objects
individually in a central location on the grid and were asked to move them to
their original location. Then the following day in session three, participants
returned for a final recall test.
The
results showed improved recall accuracy on the final test for objects that were
tested on day two compared to those not tested on day two. However, people
never recalled exactly the right location. Most importantly, in session three
they tended to place the object closer to the incorrect location they recalled
during day two rather than the correct location from day one.
"Our
findings show that incorrect recollection of the object's location on day two
influenced how people remembered the object's location on day three,"
Bridge explained. "Retrieving the memory didn't simply reinforce the
original association. Rather, it altered memory storage to reinforce the
location that was recalled at session two."
Bridge's
findings also were supported when she measured participants' neural signals
--the electrical activity of the brain -- during session two. She wanted to see
if the neural signals during session two predicted anything about how people
remembered the object's location during session three.
The
results revealed a particular electrical signal when people were recalling an
object location during session two. This signal was greater when -- the next
day -- the object was placed close to that location recalled during session
two. When the electrical signal was weaker, recall of the object location was
likely to be less distorted.
"The
strong signal seems to indicate that a new memory was being laid down,"
Bridge said, "and the new memory caused a bias to make the same mistake
again."
"This
study shows how memories normally change over time, sometimes becoming
distorted," Paller noted. "When you think back to an event that
happened to you long ago -- say your first day at school -- you actually may be
recalling information you retrieved about that event at some later time, not
the original event."
The
research was supported by National Science Foundation grant BCS1025697 and
National Institute of Neurological Disorders and Stroke of the National
Institutes of Health grant T32 NS047987.
Story Source:
The
above story is reprinted from materials provided by Northwestern
University. The original article
was written by Marla Paul.
Note: Materials may be edited for content and length. For further
information, please contact the source cited above.
Journal Reference:
1. D. J. Bridge, K. A. Paller. Neural
Correlates of Reactivation and Retrieval-Induced Distortion. Journal
of Neuroscience, 2012; 32 (35): 12144 DOI:10.1523/JNEUROSCI.1378-12.2012
Northwestern University (2012, September 19). Your memory is like
the telephone game, altered with each retelling. ScienceDaily.
Retrieved September 19, 2012, from http://www.sciencedaily.com/releases/2012/09/120919125736.htm
