New ‘Unconscious’ Therapies Could Help Treat Phobias

These therapies dampen fears absent direct exposure—no need to be in the room with a live tarantula

Large spider hanging upside down in silhouette in the center of a rounded spot of a light

Mats Silvan/Getty Images

If you’re terrified of spiders, a psychiatrist might suggest facing your fears through seeing pictures or getting close to the real thing—not just one time but over and over. For someone with arachnophobia, this sounds like a worst nightmare.

Such “exposure therapy” is a frontline treatment for phobias and other fear-related conditions. There is good evidence that it works—if the patient can be convinced to begin and they manage to stick with it. When nothing bad happens in feared situations repeatedly, we eventually learn not to be afraid. There’s no denying that it’s distressing, though, and dropout rates can be as high as 45 percent. “People miss their exposure therapy appointments more often than they do their dental appointments,” says psychologist Paul Siegel of Purchase College.

Alternatively, what if we could expose people to their fears without them being consciously aware of it, allowing them to sidestep the distress while still reaping the therapeutic benefits? It sounds outlandish, but a recent review of studies of different approaches to “unconscious exposure therapy” concluded there is “ample evidence” that this approach is valid. These techniques could improve exposure therapy compliance and may have broader implications for treating conditions such as post-traumatic stress disorder (PTSD) and social anxiety.


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The review, conducted by Siegel and pediatric psychiatrist Bradley Peterson of the University of Southern California and Children's Hospital Los Angeles, collated results from 39 studies encompassing 10 different techniques; 38 of them found positive effects. The researchers found that, overall, the approach is remarkably effective. “The unconscious exposure paradigm contradicts what’s considered sacred dogma in cognitive behaviorism and clinical psychology,” Siegel says, “which is that if people are going to get over their fears, they have to confront them.”

The first study to investigate whether unconscious exposure to a fearful stimulus could reduce anxiety was published in 1978 and involved a film that was presented subliminally.

Researchers reduced the film’s illumination and superimposed a gray box on the projection area, obscuring the movie. Participants with agoraphobia (a fear of being overwhelmed in public places) reported seeing “nothing,” yet films that depicted situations such as crowded markets and public transportation reduced their symptoms. This study’s methods had limitations, though, and subsequent research has used more rigorous approaches to assess participants’ awareness of unconsciously presented stimuli.

Siegel’s own work involves “very brief exposure,” or VBE, which exploits a perceptual phenomenon called backward masking. Many images of feared stimuli such as spiders are presented for extremely brief intervals (a few hundredths of a second), each immediately followed by a second, innocuous image, shown for much longer, that has nothing to do with what induced the fearful reaction. Because the image of feared stimuli is shown very briefly and the longer-lasting image appears immediately afterward, viewers are typically not consciously aware of seeing the first image, but studies show that pictures presented this way still engage unconscious brain processes.

Over the past 15 years Siegel and his colleagues have investigated VBE therapy with seven randomized, double-blind, placebo-controlled trials, the gold standard for clinical evidence. Most of these studies recruited participants with levels of arachnophobia that would qualify for a diagnosis and included a test involving approaching a spider. “To determine if VBE is effective in my lab, we don’t kid around,” Siegel says. “We put them in a room with a live tarantula and see how much closer they can get to it.” He and his colleagues have repeatedly found that VBE significantly increases how close participants get to the tarantula and reduces the fear they report while doing so. One follow-up assessment found that these effects can persist for a year.

Another technique, called “decoded neurofeedback,” or DecNef, involves coaxing people to produce brain activity corresponding to a fear without showing them the fear-causing stimulus itself. “We use [functional magnetic resonance imaging] to first figure out patterns of brain activity representing the perception of some animals, such as spiders and snakes,” says Hakwan Lau, a psychologist now at the Institute for Basic Science in South Korea, who led the team that developed DecNef. “Then we look for occurrences of these patterns while people are still inside the scanner.”

Participants are shown visual feedback representing their brain activity and rewarded for making it more closely match a target pattern. “We train people to activate that representation in their brain over the course of five sessions,” says Vincent Taschereau-Dumouchel, a neuroscientist now at the University of Montreal, who led several DecNef studies. The process, he says, is intended to produce a type of unconscious exposure. The researchers measured skin conductance (a physiological indicator of fear) and the activity of the amygdala (the brain’s chief emotion center) and found that DecNef reduces these biological fear markers for the targeted animal.

Other approaches include bypassing conscious awareness by presenting stimuli that have been linked to fear, such as odors or sounds, during sleep. Another, called “spiderless arachnophobia therapy,” involves presenting pictures of objects that have arachnoid features, such as a tripod with spiderlike legs.

Some studies covered in the review investigated what happens in the brain when feared stimuli are presented subconsciously, mostly using VBE. These experiments have found that subconscious presentation activates emotion regulation circuits and regions, including the amygdala, where unconscious fear memories are thought to be stored. The amygdala is activated during subconscious presentation, but its subsequent responsiveness to feared stimuli is reduced.

Two brain circuits, studies suggest, underlie fear: a conscious, cognitive system that stores explicit knowledge and beliefs about fears and an unconscious system that activates automatic, physiological responses and that operates much more rapidly. Unconscious exposure may alter fear memories stored in the amygdala via the circuit that operates on an unconscious level. These systems are thought to interact, but exactly how is not clear.

In DecNef studies so far, effects on biological responses did not alter conscious fears. “Because the procedure is nonconscious, it only changes the nonconscious reactions; it doesn’t change conscious fear itself,” Lau says. “But we’re hoping that as the methods get better, eventually the effect will be large enough to impact conscious fear, too.”

In VBE studies, though, participants did report lower subjective fear when approaching the spider, suggesting that reduced automatic, unconscious responses may allow conscious changes to take place more readily. This suggests that the most effective use of these unconscious techniques may be as an adjunct to traditional exposure therapies. “This can take the edge off,” Siegel says. “I’ve seen it can reduce someone’s fears just enough so that it’s easier for them to engage in exposure, and I’d say clinically, that’s really the goal.”

These findings may have broader relevance than just fear of spiders. “The basic mechanisms of fear, as far as we know, work whether you’re afraid of heights, public speaking, blood, traumatic memories or interacting with strangers,” Siegel says. “We’re in the middle of studies where we’re applying VBE to social anxiety disorder in young adults and combat veterans who’ve been traumatized in Iraq and Afghanistan.”

Simon Makin is a freelance science journalist based in the U.K. His work has appeared in New Scientist, the Economist, Scientific American and Nature, among others. He covers the life sciences and specializes in neuroscience, psychology and mental health. Follow Makin on X (formerly Twitter) @SimonMakin

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