How Could VR and Brain Signals Personalise Arachnophobia Treatment?

Objective measurement data instead of subjective assessment

A fear of spiders is one of the most common specific phobias. Exposure therapy is an effective treatment. Those affected are gradually exposed to the fear-inducing stimulus to achieve habituation. As part of the therapy, virtual reality applications are also used as a safe and cost-effective alternative to encounters with real spiders. With these so-called VRET (Virtual Reality Exposure Therapy) systems, therapists usually adjust the intensity of the confrontation based on subjective impressions.

In contrast, the VRSpi system, initially developed within the framework of a master's thesis (Weber et al. 2024) under the supervision of Selina C. Wriessnegger at the Institute of Neural Engineering, regulates the intensity of fear stimuli based on objective neurophysiological parameters. "The brain waves and heart rate provide us with reliable indications of how much stress someone is currently experiencing," says Selina Wriessnegger. The frontal alpha asymmetry in the EEG proved to be particularly significant. In the case of anxiety, the right frontal lobe of the brain is more strongly activated.

Experimental Setup

21 healthy participants participated in a follow-up feasibility study of the new system. They wore EEG caps and VR goggles and were exposed to stimuli of varying intensity in a virtual cellar vault, ranging from individual small spiders to multiple large spiders. The participants regularly signalled how they rated their own anxiety level using hand signals. At the same time, an algorithm previously trained on the respective person analysed the EEG data in real time. As the intensity of the anxiety stimulus increased, there was a clear shift in brain activity towards the right frontal lobe.

"Our results show that anxiety can be reliably measured in the brain and that the data can be used for adaptive control of virtual environments," says Selina C. Wriessnegger. "This opens up new possibilities for personalised treatment concepts in which the exposure is dosed precisely and individually."

The hardware challenge

The hardware in particular still represents a hurdle to widespread use in clinical practice. The application of an EEG cap is not very user-friendly and requires trained personnel. Although more compact solutions such as wearables or in-ear EEG systems already exist, they do not yet achieve the same measurement accuracy.