Monday, 11 April 2016

Hanging out with virtual reality spiders helps arachnophobes see real spiders as smaller and less scary

By guest blogger Melissa Hogenboom

A little fear can be a good thing but when it develops into a phobia, it can become debilitating. One way therapists treat fear disorders is using a technique called exposure therapy. As its name suggests, it involves gradually exposing a person to the very thing they are afraid of.

The problem is that in the comfort of a therapist's office, recreating the fearful event is not always straightforward. This means patients may not be able to realistically confront what they most fear. Consider recreating a bomb going off in a war zone, confronting a fear of heights, or coming face to face with a large, hairy spider.

It is therefore becoming more popular for cognitive psychologists to use virtual reality (VR) both to study and to treat fear disorders.

Previous studies have shown that our brain can easily be tricked in a virtual world, even though we know the world is not real. A short stint assuming the perspective of a black person in VR has been shown to reduce people's racial biases and performing in front of a VR audience can alleviate anxiety for public speaking. It is even an effective tool for treating serious cases of post-traumatic stress disorder (PTSD).

Armed with this knowledge, a new study, published in the journal Biological Psychology, exposed participants with arachnophobia (a fear of spiders) first to real spiders and then to virtual ones. An example of the virtual spiders can be seen in this video, which is from a related, older study.

There were two important findings – first that these "spider phobic" participants overestimated a spider's size, secondly that this bias could then be reduced using VR.

The team, led by Dr Youssef Shiban of the University of Regensburg, Germany, recruited 41 participants with spider phobias and 20 without. The participants with the phobia first had to complete a clinical interview to asses their level of fear.

Next the researchers presented the participants with a 7.5 cm Chilean rose tarantula spider (Grammostola rosea) in a transparent box placed 3 metres away and asked them to estimate its size by pointing to differently sized lines on a piece of paper. The participants also had to bring the spider as close to themselves as they could using a lever and report their level of fear from 0 to 10.

All participants were then fitted with a VR headset and exposed to four similar spiders – this time about 30 cm long – in a virtual world for five minutes at a time. This was repeated four times, giving a total exposure time of 20 minutes. Two weeks later participants were again confronted with a real spider and asked to estimate its size, to move it closer and again report their fear levels.

Although both groups had initially over-estimated the size of the spider, the size bias was much larger in those who were scared of spiders than it was among the non-phobics (on average 81 per cent overestimation compared to 40 per cent). Two weeks after the VR treatment, the size bias of those scared of spiders dramatically decreased to 66 per cent, but the non-phobic participants did not reduce their estimations. Crucially, the phobic participants' self reported fear levels also reduced by 70 per cent, replicating similar results from a 2015 study.

It must be noted that the drop-out rate was quite high due to technical issues and failure to return to the follow up task. Of the original 41 spider phobic participants, the results of only 22 participants were included in the second exposure task, while 19 controls remained.

Though it was already known that a fear of a particular object or event can increase your attention to it, this is the first time it has been shown that individuals with arachnophobia overestimate a spider's size.

The researchers say that there were two related changes after the VR exposure. Both the fear of spiders, as well as the "overstimulation" that caused the initial size bias, were reduced.

This reveals that it is the very process of being visually confronted with a fear that can decrease it. This makes sense. Being afraid is not a pleasant experience so it is natural to avoid anything that triggers a particular fear. But when a person confronts their fears in a safe place, this sets up a spiral of beneficial effects: they learn that the object of their fear is not such a threat, and in turn this literally modifies their perception of the object to be more accurate, making it less likely that they will find it so scary in future.

Now that it is clear that VR can reduce a fear of spiders thereby changing how large they are seen, there is a strong case for using the technology in a therapeutic setting. But whether this reduction of fear is long lasting remains unclear and would require follow-up studies. Perhaps even more importantly, the study shows the powerful effect emotions have on our perception. When we are afraid, we literally see the world differently and understanding this is key to overcoming our fears.


Shiban, Y., Fruth, M., Pauli, P., Kinateder, M., Reichenberger, J., & Mühlberger, A. (2016). Treatment effect on biases in size estimation in spider phobia Biological Psychology DOI: 10.1016/j.biopsycho.2016.03.005

Post written by Melissa Hogenboom (@melissasuzanneh) for the BPS Research Digest. Melissa is BBC Earth's feature writer.

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