Could exposure therapy, without conscious exposure, actually work?

Phobias are among the most common psychological disorders, and are the most common anxiety disorder. An estimated 6% of the population suffer from full-blown arachnophobia, for example, while around 1 in 10 people in the UK are affected by claustrophobia at some point in their lives.

The standard treatment for phobias is 'exposure therapy'. For someone with a phobia of spiders, that could mean encouraging them to look at pictures of spiders, encounter virtual reality spiders, and ultimately even hold a spider — all in a safe setting. The aim is to help them to confront and overcome their fears, lessening their severity along the way.

There is abundant evidence that exposure therapy does work. But it is distressing, and this means that most people with phobias are reluctant to start therapy, or, if they do, they often drop out. A new paper in the Psychological Bulletin concludes, however, that unconscious exposure therapy — in which the person isn't even aware that they are being exposed to the object of their phobia, and so which does not stress them out — can be remarkably effective.

Paul Siegel at the State University of New York and Bradley S. Peterson at the University of Southern California conducted an exhaustive meta-analysis of findings from 39 studies that used an unconscious exposure intervention.

The interventions were not identical. In fact, the researchers identified 10 different approaches. In the 'very brief exposure' paradigm, for example, sufferers receive a series of 'microexposures' to images of their feared object (such as a spider), with each image immediately followed with another, benign image, to help to prevent it from being consciously recognised.

Another intervention, called 'spiderless arachnophobia therapy' takes a different approach. It involves showing people images of objects that resemble spiders, but which they don't consciously appreciate are spider-like — such as a camera tripod with its legs bent to resemble spiders' legs. Though the images themselves are consciously seen, this intervention relies on unconscious processing.

Overall, 38 or the 39 studies found that the intervention made a difference. Based on their analysis, Siegel and Peterson conclude that there is "ample evidence" that unconscious approaches work to reduce fear responses — even in highly phobic participants — and that they do this without inducing feelings of fear. Though the effect sizes on behaviour (willingness to approach a live spider, for example) were not quite as large as those found for standard exposure therapy for specific phobias, they were still "mostly large", the pair reports.

It's also worth noting that the vast majority of these unconscious exposure studies consisted of only a single 'treatment' session, whereas standard exposure therapy is often conducted over multiple sessions. Perhaps, then, a series of unconscious treatments may be even more effective, but further work is needed to explore this.

Based in part on brain scan data from some of these studies, the researchers think that the reason unconscious therapy can work is that our brains react both unconsciously and, separately, via different pathways, also consciously to scary things. They think that when someone with a spider phobia is repeatedly unconsciously exposed to a picture of a spider, their amygdala, which detects threats, is activated, but they don't go on to experience a racing heart or sweaty palms — or feel fear. With repeated 'training', this "likely revises the memory representation of phobic stimulus", the pair writes — so that their brain learns that this object should not trigger fear. "In essence, we are arguing that unconscious experience reduces fear by preventing fear itself," the researchers write.

Exactly which brain regions play a role in unconscious exposure therapy is not yet well understood. Neither is it clear yet which types of unconscious phobia intervention may be the most effective. But, given that specific phobias are so common, and that research shows that they often precede the development of other types of anxiety disorders, the pair argues that further research into unconscious approaches is now needed. They add that in theory, it's possible that the approach may also help people with some other anxiety disorders, such as PTSD.

"Psychologists have long maintained that feared objects and situations must be directly confronted to reduce fear of them," Siegel and Peterson write. "The findings of this review call this long-standing belief into question and suggest that a new generation of exposure therapies that reduce fear via unconscious processing is on the horizon."

However, since the unconscious and conscious memory systems that underlie fear-related learning are not completely independent, they think that the ultimate phobia treatment will probably target both systems. First, an unconscious treatment might make someone with a spider phobia, say, less terrified of spiders. This could then make it less stressful for them to embark on standard exposure therapy, in which the conscious, cognitive processes of phobic beliefs and subjective fear are tackled.

Read the paper in full:
Siegel, P., & Peterson, B. S. (2024). "All we have to fear is fear itself": Paradigms for reducing fear by preventing awareness of it. Psychological Bulletin, 150(9), 1118–1154. https://doi.org/10.1037/bul0000437

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