During one of my favorite shows, Criminal Minds, one of the FBI agents, Spencer, tries to remember a crime taking place during his childhood. He has reoccurring dreams about this murder that he may or may not have encountered when he was a young child. To try and get him to remember these vivid dreams, he goes to a hypnotist.
Hypnosis is a set of techniques that provides people with suggestions for alterations in their perceptions, thoughts, feelings, and behaviors. So in other words, a person is put under a sleep like sort of state, and this ensures that the mind is relaxed and will respond to commands that the hypnotist says to do. When I first saw this episode of criminal minds, I wanted to know if it was actually possible to recover memories. If that was possible, then why aren't criminal investigators able to do it more often? Mythbusters did an episode to find out if this actually can happen in real life.
Below is a link from a scholarly journal from 1983 that investigates whether or not hypnotics is able to enhance the memory of witnesses.
"Despite the publication of a large number
of case studies in which hypnosis has apparently
been invaluable in the solving of a crime,
experimental attempts to demonstrate improved
memory under hypnosis have thus far
not been successful. It has been suggested that
the failure of laboratory studies to demonstrate
hypnotic memory enhancement may result
from the absence of certain essential features
present in the crime situation, such as meaningful,
dynamic stimulus materials, high emotional
arousal, and the realization that a human
life may depend on what is recalled. Furthermore,
the study of stimulus events in the
crime situation is rarely done intentionally, as
it is in the laboratory. However, several recent
laboratory studies that have attempted to include
these very characteristics nonetheless
persist in failing to demonstrate hypnotic
memory enhancement. One exception worth
pursuing is the suggestion of improved recall
under hypnosis for incidentally learned materials.
What these studies do demonstrate
quite clearly, however, is that when witnesses
are interrogated under hypnosis they are more
suggestible, showing a greater tendency to agree
with the interrogator. Because of this problem,
and an apparent trend for the courts to reject
the testimony of witnesses who have undergone
hypnosis, a search for nonhypnotic procedures
of memory enhancement appears warranted.
Three factors that may be responsible for the
improved memory under hypnosis reported
in so many anecdotes were suggested: (a) encouraging
witnesses to lower their criterion
level during memory retrieval; (b) contextual
reinstatement via a guided memory procedure;
and (c) repeated testing sessions that allow for
the occurrence of experimental hypermnesia.
If witnesses to a crime may be helped to remember
the details of the crime through the
application of these procedures without hypnosis,
the benefits of memory enhancement
could be achieved without the problematic effects
of bias inherent in hypnosis. Future research
to investigate these factors is required."
Woah. So the studies couldn't be taken in for account because they need more research. This needs replicability. I worked in Mythbusters, and in Criminal Minds, however, in an actual research setting, the experiments were not able to provide complete information. So, sorry criminal case solvers, but your job may have just gotten harder.