Single Session Virtual Reality Therapy in Acrophobia - and the Role of Respiration

In recent years, in the treatment of phobias, exposure therapy in virtual reality is becoming more and more popular as an alternative for in-vivo exposure. Effectiveness of virtual reality exposure therapy (VRET) is comparable to in-vivo exposure therapy, though several characteristics of the VRET have an impact on the outcome of the therapy (e.g., immersion into the virtual environment (VE), familiarity with the VE). Additionally, the use of VRET varies from multiple exposure sessions to single-session VRET. Single-session therapy has an economic advantage and in in-vivo, post therapy outcomes show good results. In virtual reality, the assessment of outcome post therapy and in follow-up of single-session therapies is still needed for an evaluation of this approach. As an outcome measure, behavioral assessments are especially relevant for effectiveness studies as in fear of heights it is closer to the individual's life to know how high they voluntarily go up a building than to have hypothetical self-report questionnaire results. Much research has been conducted on physiological correlates of the subjective experience of fear in exposure therapy as they are assumed to be a prerequisite for effective exposure treatment. Skin conductance level (SCL) and heart rate can be used for objective manipulation checks of exposure therapy. SCL is found to increase during fearful situations independent of setting while heart rate only increases during in-vivo exposure. Contrary to heart rate, heart rate variability (HRV) is not thoroughly studied in VRET yet. HRV is associated with the adaptability of an organism to new environments and cognitive functioning. High Frequency HRV is found to be reduced in individuals with mental disorders, and positive and negative mood inductions lead to differential HRV responses overall. Respiration is a well-studied correlate of emotional experience and especially of the experience of fear and anxiety. In a series of experiments, it was found