Based on EEG data and heart rate, the system adjusts the intensity of the exposure to the anxiety level of the participants.

Researchers at Graz University of Technology (TU Graz) have developed a novel virtual reality (VR) system that could make the treatment of arachnophobia, also known as spider phobia, more targeted and personalised in the future. The “VRSpi” system is a prototype which analyses the EEG data and heart rate of the participants during a confrontation with spiders in a VR environment. Based on this objective measurement data, it adjusts the intensity of the stimuli in real time to the person’s current level of anxiety. This avoids over- or under-stimulation and optimises the effectiveness of the exposure in order to get the users used to the creatures.

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 confronted with the fear-inducing stimulus in order 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 this 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, which was 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 the 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 took part in a follow-up feasibility study for the new system. They wore EEG caps and VR goggles and were exposed to stimuli of varying intensity in a virtual cellar vault – from individual small spiders to a number of 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.