By Jonny Lupsha, News Writer

A Londoner climbed The Shard, a 310-meter skyscraper, mostly without ropes, The Guardian reported Monday. Although he isn’t the first person to scale the building, his disregard for his own safety raises questions about our individual personalities. Why do we engage in high-risk activities?

The identity of The Shard climber is still unknown, but according to the article in The Guardian, police responded to a 5:15 a.m. call reporting the man scaling the building. Local law enforcement was joined by emergency services, and although the man was spoken to by the police, no arrest was made. Although Greenpeace activists performed this feat in protest several years ago, the motives of this week’s climber haven’t been reported, leaving open the possibility that he’s a thrill-seeker or amateur daredevil, pushing himself to his own limits for fun. Interestingly, human personalities differ greatly, sometimes producing high-risk behaviors.

Approach and Avoidance

Why are we attracted to some activities and not others? “Many theorists have suggested that the most basic distinction that underlies virtually all behavior is the distinction between approach and avoidance,” said Dr. Mark Leary, the Garonzik Family Professor of Psychology and Neuroscience at Duke University. “That is, at the most basic level, virtually every behavioral reaction involves either approaching situations and activities and doing things, or else avoiding situations and activities and not doing things. Your life is a never-ending journey through the land of approach and avoidance.”

Dr. Leary said that approach and avoidance are governed by two distinct systems in the brain—the behavioral activation system (BAS), for approach; and the behavioral inhibition system (BIS), for avoidance. “Think for a moment about why you approach and engage in certain activities,” he said. “Generally, it’s because you expect that the behavior will bring about a reward, or at least that it will be more rewarding than something else that you might do instead. Whenever rewards are salient, the BAS kicks on, orients you toward the rewarding activity, and motivates you toward doing the rewarding behavior.”

The BIS is the opposite, even governing the cessation of an ongoing behavior. “The BIS is sensitive to possible punishments,” Dr. Leary said. “So if you’re reluctant to introduce yourself to someone because you’re afraid of rejection, your BIS is active. Or when you stop suddenly because you see a snake on the path ahead of you, or when you procrastinate because you don’t want to do something unpleasant, the BIS is operating.”

Neurotransmitters and Thrill-Seeking

People like Monday’s Shard climber who seek sensations are commonly known as thrill-seekers. Some might say “their brains are wired differently than other peoples’,” but that’s only half the story. The other half of the story is the enzyme Monoamine Oxidase, or MAO for short. “MAO maintains a proper level of neurotransmitters in the synapses between neurons,” Dr. Leary said. “Monoamine Oxidase helps to break down neurotransmitters after they’re released into the synapse; so if your level of monoamine oxidase is low, certain neurons will continue to fire and you’ll have excessive activity in certain areas of the brain.”

According to Dr. Leary, many researchers believe this excess brain activity causes people to seek out more stimulation and sensations. He even cited bullfighters as having an abnormally low level of MAO, which supports this theory. On the contrary, people with higher levels of MAO tend to enjoy quiet, still activities more, including their choices of career.

Science hasn’t clearly linked every part of the brain with every activity or behavior humans exhibit. However, both monoamine oxidase research and the study of approach and avoidance give reasonable theories about thrill-seeking behaviors—even free-climbing skyscrapers.

Professor Mark Leary contributed to this article. Dr. Leary is Garonzik Family Professor of Psychology and Neuroscience at Duke University. He earned his bachelor’s degree in Psychology from West Virginia Wesleyan College and his master’s and doctoral degrees in Social Psychology from the University of Florida.