94 | SCIENTIFIC AMERICAN | SPECIAL EDITION | WINTER 2022
Answering Queries
in Real Time
while Dreaming
Researchers demonstrate that during REM sleep,
people can hear—and respond to—simple questions such as
“What is eight minus six?”
By Diana Kwon
D
reams are full of possibilities;
by drifting into the world beyond
our waking realities, we can visit
magical lands, travel through time and in-
teract with long-lost family and friends.
The notion of communicating in real time
with someone outside of our dream-
scapes, however, sounds like science fic-
tion. A recent study demonstrates that, to
some extent, this seeming fantasy can be
made real.
Scientists already knew that one-way
contact is attainable. Previous studies
have demonstrated that people can pro-
cess external cues, such as sounds and
smells, while asleep. There is also evi-
dence that people are able to send mes-
sages in the other direction: lucid dream-
ers—those who can become aware they
are in a dream—can be trained to signal,
using eye movements, that they are in the
midst of a dream.
Two-way communication, however, is
more complex. It requires a person who is
asleep to actually understand what they
hear from the outside and think about it
logically enough to generate an answer,
explains Ken Paller, a cognitive neuro-
scientist at Northwestern University. “We
believed that it was going to be possible—
but until we actually demonstrated it, we
weren’t sure.”
For this study, Paller and his colleagues
recruited volunteers who said they remem-
bered at least one dream per week and pro-
vided them with guidance on how to lucid
dream. They were also trained to respond
to simple math problems by moving their
eyes back and forth—for example, the cor-
rect response to “eight minus six” would be
to move your eyes to the left and right
twice. While the participants slept, elec-
trodes attached to their faces picked up
their eye movements, and electroencepha-
lography (EEG)—a method of monitoring
brain activity—kept track of what stage of
sleep they were in.
As Paller’s team was conducting these
experiments, the researchers discovered
three groups in Germany, France and the
Netherlands who were trying to accom-
plish the same thing. Instead of competing,
the groups decided to collaborate. They
carried out similar experiments, though
with slightly different methods of answer-
ing questions and receiving responses. The
German group, for example, transmitted
its math problems using Morse code, andthe French group asked its participant—
a person with narcolepsy who had expert
lucid-dreaming abilities—to answer yes-or-
no questions with facial muscle contrac-
tions rather than eye movements.
Across the four studies, there were a to-
tal of 36 participants and 158 trials during
which the researchers could verify lucid
dreaming and attempted to establish con-
tact. Answers were considered correct if
three of four raters were in agreement on
whether the responses, sometimes very
subtle movements, were accurate. Correct
responses were given in 18 percent of trials;
another 18 percent were classified as am-
biguous because raters could not come to a
consensus about whether participants gave
a correct response or whether they had re-
sponded at all. Incorrect responses were
given in 3 percent of the trials. Overall
there was no response in 60 percent.
One of the co-authors, Karen Konkoly,
a graduate student in Paller’s lab, specu-
lates that participants failed to respond in
60 percent of the trials because they sim-
ply did not perceive the incoming com-
munication. In those cases, they rarely re-
ported any incorporation of the questions
into their dreams after waking up. But