78
PHYSICS OF THE IMPOSSIBLE
should pull on the magic donkey's tail. If the donkey began to talk, it
meant the suspect was a liar. If the donkey remained silent, then the
suspect was telling the truth. (But secretly, the elder would put soot on
the donkey's tail.)
After the suspect was taken out of the room, the suspect would
usually proclaim his innocence because the donkey did not speak
when he pulled its tail. But the priest would then examine the suspect's
hands. If the hands were clean, it meant he was lying. (Sometimes the
threat of using a lie detector is more effective than the lie detector itself.)
The first "magic donkey" in modern times was created in 1913,
when psychologist William Marston wrote about analyzing a person's
blood pressure, which would be elevated when telling a lie. (This observation about blood pressure actually goes back to ancient times,
when a suspect would be questioned while an investigator held on to
his hands.) The idea soon caught on, and soon even the Department of
Defense was setting up its own Polygraph Institute.
But over the years it has become clear that lie detectors can be
fooled by sociopaths who show no remorse for their actions. The most
famous case was that of the CIA double agent Aldrich Ames, who
pocketed huge sums of money from the former Soviet Union by sending scores of U.S. agents to their death and divulging secrets of the U.S.
nuclear navy. For decades Ames sailed through a battery of the CIA's
lie detector tests. So, too, did serial killer Gary Ridgway, known as the
notorious Green River Killer; he killed as many as fifty women.
In 2003 the U.S. National Academy of Sciences issued a scathing
report on the reliability of lie detectors, listing all the ways in which lie
detectors could be fooled and innocent people branded as liars.
But if lie detectors measure only anxiety levels, what about measuring the brain itself? The idea of looking into brain activity to ferret
out lies dates back twenty years, to the work of Peter Rosenfeld of
Northwestern University, who observed that EE G scans of people in
the process of lying showed a different pattern in the P300 waves than
when those people were telling the truth. (P300 waves are often stim-
PHYSICS OF THE IMPOSSIBLE
should pull on the magic donkey's tail. If the donkey began to talk, it
meant the suspect was a liar. If the donkey remained silent, then the
suspect was telling the truth. (But secretly, the elder would put soot on
the donkey's tail.)
After the suspect was taken out of the room, the suspect would
usually proclaim his innocence because the donkey did not speak
when he pulled its tail. But the priest would then examine the suspect's
hands. If the hands were clean, it meant he was lying. (Sometimes the
threat of using a lie detector is more effective than the lie detector itself.)
The first "magic donkey" in modern times was created in 1913,
when psychologist William Marston wrote about analyzing a person's
blood pressure, which would be elevated when telling a lie. (This observation about blood pressure actually goes back to ancient times,
when a suspect would be questioned while an investigator held on to
his hands.) The idea soon caught on, and soon even the Department of
Defense was setting up its own Polygraph Institute.
But over the years it has become clear that lie detectors can be
fooled by sociopaths who show no remorse for their actions. The most
famous case was that of the CIA double agent Aldrich Ames, who
pocketed huge sums of money from the former Soviet Union by sending scores of U.S. agents to their death and divulging secrets of the U.S.
nuclear navy. For decades Ames sailed through a battery of the CIA's
lie detector tests. So, too, did serial killer Gary Ridgway, known as the
notorious Green River Killer; he killed as many as fifty women.
In 2003 the U.S. National Academy of Sciences issued a scathing
report on the reliability of lie detectors, listing all the ways in which lie
detectors could be fooled and innocent people branded as liars.
But if lie detectors measure only anxiety levels, what about measuring the brain itself? The idea of looking into brain activity to ferret
out lies dates back twenty years, to the work of Peter Rosenfeld of
Northwestern University, who observed that EE G scans of people in
the process of lying showed a different pattern in the P300 waves than
when those people were telling the truth. (P300 waves are often stim-