Why did they believe so strongly in something that is so implausible? In answers to a questionnaire, the abductees scored high on personality traits that make them a bit different. For example, just because an idea seems magical doesn't necessarily mean it isn't true.
People with those traits tend to have "a rich fantasy life, and to endorse unconventional beliefs," the researchers say in their report.
And the stories they told were anything but conventional, yet they had much in common, McNally says.
"I would ask them, how did this all begin," McNally says. "And they would typically say 'I was lying in bed one night, and a few hours before dawn I suddenly woke up. I tried to move over and I realized I was completely paralyzed. It was absolutely terrifying. I felt electrical sensations coursing through my body, I heard humming noises, I saw lights flashing, and I felt myself levitating off my bed when suddenly I saw these strange beings, these strange figures coming up towards the bed. And then I blanked out. Later, I woke up and had no idea what had happened.' "
Some time later, McNally says, while in therapy, the memories came back.
"'I was taken up into a spaceship, medically probed, met alien beings, met my hybrid children,' " the participants told him. They frequently said they had sex with the aliens.
To the abductees, that meant they were something special.
All described the abduction as terrifying, but when McNally asked them if they wished it had never happened, they all said it was worth it. The abduction proved there were other beings out there who cared for us, and for our planet, and even wanted to mate with humans to ensure continued survival of life on Earth.
"Their experience with these alien beings ultimately becomes sort of a spiritually deepening one for them," McNally says.
Most of the participants came from traditional religious backgrounds, but had drifted away.
"These individuals have strong spiritual needs that are not being met by conventional religions," McNally suggests.
Whatever the cause, the research shows clearly that to these people, the memories are real, even though it's safe to say the events never happened. But there's no point in trying to convince them.
Even if he could explain to them exactly why they thought all this happened, and show convincing reasons why the memories are false, "I strongly suspect they would not buy it," he says.
"A naturalistic explanation robs the universe of its magic," he says.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.