People seem to be attracted by morbid stuff, like horror films or haunted houses. In many cultures, there are even feasts of terror, and we can just think about the Halloween from the Western Culture, not mentioning thousands of tribal traditions of the fear.

The human brain's capacity to check fear could be used to treat phobias and anxiety disorders. Fear triggers automatic "fight or flight" body response like increased heart rates, accelerated breathing, increased muscle tone and attention, in order to react quickly and effectively to danger. "It's nature's way of protecting us," said clinical psychologist David Rudd at Texas Tech University. "If the brain knows there is no risk of really being harmed, it experiences this adrenaline rush as enjoyable," Rudd explained.

In fact, the proper level of risk is what makes us enjoy potentially harmful situations. "Young children may overestimate the risk of harm and experience true 'fear.' When that happens you see the child cling to a parent and cry, convinced there's a very real chance of harm," Rudd told, while "adults may well scream but quickly follow it with a laugh since they readily recognize there's no chance for real harm."

This terror thrills explain why people enjoy extreme sports like skydiving, bungee jumping, risky trips and so on. "In these cases, those engaging in high-risk activities will tell you that the risk is lowered by their training and precautions," turning the activity in something enjoyable. "The key structure in the brain responsible for this effect is likely the amygdala" (the emotional center of the brain) said Rudd.

In our evolution "we were motivated to seek out this kind of stimulation to explore new possibilities, to find new sources of food, better places to live and good allies," said Frank McAndrew, environmental psychologist at Knox College in Galesburg, Illinois.

New situations often supposed exposure to new unknown dangers. "People enjoy deviations from the norm-a change of pace, within limits." In fact, daring behavior within some assumed level of risk might have been the key to the success of our species. Exposing the brain repeatedly to fearsome situations will accustom it to fear, thus the brain will no longer perceive it as a frightening experience. "This is a key behind cognitive therapies for anxiety dysfunctions such as phobias and post-traumatic stress disorder, where a person's system overreacts to perceive something as threatening when it is not," Rudd said.

Cognitive therapies combined with medicines can improve up to 80 % of the disorder's symptoms. McAndrew explained what makes houses be like haunted: "We're focusing on what architectural features make houses appear haunted or not," he said.

"We're finding they tend to be laid out in a confusing way, so that you're not sure where you are in the house. They're high in 'mystery'-you can't see very far in the house. And there are all kinds of sounds and smells not usually found in a house that can make it seem creepy."