What counts as a phobia?

Plenty of people get the heebie-jeebies when they stand near the edge of a high cliff, and many would prefer not to pet a tarantula or cradle a boa constrictor. But for some people, their fears surrounding a particular situation grow to be out of proportion with the actual danger it poses.

In that case, these individuals may be diagnosed with a specific phobia. Specific phobia refers to an extreme fear or anxiety about a certain object or situation. Colloquially, people sometimes say they have a phobia of something they're fearful or wary of — but what really counts as a specific phobia, as it's understood in psychology?

To qualify as a specific phobia, a fear must be persistent — it happens each time the object or situation is encountered — and it must interfere with a person's daily life, affecting their hobbies, relationships or work, for instance.

"You have to cross the line of what’s called 'distress' or 'impairment,'" said Ellen Hendriksen, a clinical psychologist at Boston University's Center for Anxiety and Related Disorders. "Distress, meaning it freaks you out, and impairment, meaning it keeps you from living the life you want to live," Hendriksen told Live Science.

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According to Martin Antony, a clinical psychologist at Toronto Metropolitan University who leads an anxiety research and treatment laboratory, psychologists break specific phobias into these five categories:

• Animals: All animals fall under this category. Snakes and spiders are common triggers, with studies in different countries finding that spider phobias affect between 2.7% and 9.5% of the population.
• Natural environment: A fear of heights, a fear of water, and a fear of storms are some examples of phobias triggered by features of nature.
• Blood, injury, injection: These phobias involve the fear of needles, surgery, blood or similar stimuli.
• Situational: Situational phobias involve a fear of being in a certain situation or environment. Driving, flying and being in elevators are common examples of these phobias.
• Other: This category covers anything that doesn't fall into the other four categories, such as a fear of clowns or of costumed figures. "People can be afraid of anything," Antony said.

Sometimes, specific phobias develop after a person experiences a traumatic event, or after they have a panic attack that then gets associated with the environment and leads to a self-reinforcing fear of that scenario, said Sandra Capaldi, a clinical psychologist at the University of Pennsylvania Perelman School of Medicine. For example, someone who has a panic attack while they happen to be driving might develop a phobia of getting behind the wheel again for fear that they might have another attack and wreck the car.

However, sometimes phobias develop without any particular trigger. In many cases, these are phobias that center around something that's actually dangerous — like falling from a height — but a person's fear is out of proportion with the actual risk.

"This anxiety that's associated with the fear is overestimating both the likelihood that they're going to encounter some sort of featured object of the situation, or [overestimating] the intensity and the severity of the consequence," Capaldi said.

People with one anxiety disorder are more likely to have another anxiety disorder, Antony said, so specific phobias sometimes co-occur with generalized anxiety or panic disorders. On occasion, these disorders can overlap in a way that makes them tricky to diagnose.

Antony once treated a woman with social anxiety who also feared driving. He eventually realized that her fear of driving wasn't a specific phobia, though. She didn't fear crashing, he said, but rather that other drivers would judge her on the road. In her case, the driving fear was an offshoot of her social anxiety, rather than a specific phobia.

"The diagnosis isn't always clear-cut, and you can't always go by the situation people fear," Antony said. "You also have to look at why they fear that situation."

Fortunately, phobias have a well-researched and very effective treatment. The gold standard is exposure therapy, in which the patient gradually faces their fear in a controlled manner and environment. A person who has a phobia of snakes might first look at a squiggly line on a piece of paper, then a cartoon drawing of a snake, then a photo of a snake and, finally, the real thing.

"We want to push the client out of their comfort zone, but not into a panic zone," Hendriksen said. "The zone in between that is what I call the 'learning zone.' We do something a little bit hard, and it does activate our anxiety. But then when the feared outcome doesn't happen, our fear doesn't get reinforced."

The patient is in control of this process, Hendriksen added. They're never surprised by any stimuli and can decide how they want to proceed. Patients may start the treatment in a therapist's office and gradually move to the real world. Someone with a phobia of elevators might start by looking at pictures or videos of elevators, then eventually step on a real elevator themselves, for example.

Psychologists help the person monitor their anxiety throughout the process, aiming to keep the patient in a place of discomfort but not panic. As the person experiences the anxiety without any actual danger from the phobia trigger, the brain's fear system becomes desensitized and the anxiety gradually decreases.

In some special cases, psychologists might recommend an additional therapy alongside exposure therapy. This is most often true in the case of blood, injury or injection fears, Antony said.

About 70% of people with a blood phobia and half of those with a needle phobia report a fear of fainting, which is caused by an involuntary reflex called the vasovagal response. Being prone to fainting, at baseline, probably reinforces the phobia in these people; in other words, their fear of the situation is validated when they really do faint. So, in these cases, a patient might also practice a strategy called "applied muscle tension." This involves tightening certain muscles to reduce the vasovagal response, which helps prevent fainting.