Memory by hypnosis

Hypnosis can seem like magic. When in this dreamlike state, people are easily convinced to do things they wouldn’t normally do.

Now, scientists have used hypnosis to study the mind’s amazing and mysterious ability to focus on certain memories (such as the answer to a test question) while suppressing others (like what you did during vacation 3 years ago). The study may help explain how memory works and why it sometimes fails.

While hypnotized, study participants were asked to forget—and then remember again—these scenes from a documentary film.

The Dudai Laboratory, Weizmann Institute

To peer into how the brain digs up memories, researchers from the Weizmann Institute of Science in Rehovot, Israel, showed people a documentary film. A week later, the scientists attempted to hypnotize the viewers. Some of the study participants were easily hypnotized. Others were not.

While under hypnosis, participants were told to forget the movie. They were then brought out of the hypnotic state and asked to respond to a set of yes-or-no questions about the movie. While they answered the questions, scanners monitored activity in their brains.

Participants then went through the process a second time. But this time, they were told to remember the movie.

Brain scans showed clear differences between people who succumbed to hypnosis and those who didn’t. In general, those who weren’t hypnotized showed more activity in more parts of their brains than those who were. But the people who entered the trancelike state showed extra activity in a part of the brain called the prefrontal cortex.

The researchers think that this area of the brain may be responsible for preventing a person from recalling certain memories. So, the prefrontal cortex might be the executive decision maker on whether you remember something or not.

Going Deeper:

Maxmen, Amy. 2008. Mind control: Hypnosis offers amnesia clues. Science News 173(Jan. 12):20. Available at http://www.sciencenews.org/articles/20080112/fob3.asp .