London, Aug 11: The reason why horror films make some people scream, while others laugh, has been unravelled by an international team of German and American researchers.
Dr. Martin Reuter of the University of Bonn says that such wildly different reactions to horror films among people may be linked to different versions of a gene called COMT, linked to feelings of anxiety.
He and his colleagues showed 96 women pictures that were emotionally pleasant (such as animals or babies), neutral (such as a power outlet or hairdryer), or aversive (such as weapons or injured victims at a crime scene).
The participants saw 12 pictures of each type for six seconds each.
A loud, 35-millisecond white noise, called a startle probe, sounded at random while they watched.
When participants blinked, showing the startle response, a bioamplifier took readings from the electrodes, and sent the information to a computer for analysis.
The researchers observed that people with two copies of one version of the gene were more easily disturbed when viewing unpleasant pictures.
According to them, that version of the gene weakens the effect of a signalling chemical in the brain that helps control certain emotions.
The scientists also observed that people carrying two copies of it were significantly more startled by frightening images than others.
However, people who had one copy of the gene, and one copy of another version were able to control their emotions.
The team also found that people with two copies of the latter gene were also able to keep a lid on their anxiety more easily.
A single gene variation, says Montag, can explain only a small portion of variation in anxious behaviour - otherwise, in theory, up to half the population could be anxious.
"This single gene variation is potentially only one of many factors influencing such a complex trait as anxiety," Telegraph quoted co-author Christian Montag, Dipl. Psych and one of the Bonn researchers as saying.
"Still, to identify the first candidates for genes associated with an anxiety-prone personality is a step in the right direction," he added.