After screening (including parts of the Mini-DIPS), participants will receive a pre-assessment with a baseline heartrate measurement, self-report measures and two BATs (with the treated spider and the non-treated spider). All participants receive a brief psychoeducation & video demonstration of exposure steps. Participants are randomly assigned to the three study arms and are then set to receive a single session of either in vivo exposure (IVET), videochat based vicarious exposure (VicET) or neither (Waiting List Control, WLC). Approximately 24 hours later, the two BATs with both spiders, a slightly reduced set of self-report measures and an interview will conduct the post-assessment. The order of all BATs, the spider individuals (treated vs. non-treated spider) and assignment to study arms will be randomized using a list that will be worked through in a sequence determined using "www.random.org". At a six-week follow-up, another long-term assessment will be conducted. Here, participants will receive a brief online questionnaire related to their experiences with spiders and self-report measures that were previously administered. Participants previously assigned to the waiting list control (WLC) will be invited to participate in an in-vivo exposure session. A set of questionnaires including demographic information, VAS scales on the current psychological state and wellbeing (administered at the start and end of the first and second assessment day), the BDI-II, the STAI-T and STAI-S, FEE, SPQ, SBQ, FSQ, GSE, SEQ-SP, TC/E for treatment credibility and the "positive attitudes towards technology subscale" of the MTUA will be used. BDI-II, STAI and MTUA are only administered at pre-assessment. The SAS is used for initial screening.

Exposure therapy is an effective treatment for phobic fears and anxiety disorders that is considered in treatment guidelines as a first-choice treatment for e.g. specific phobia. However, many anxiety patients do not receive exposure therapy due to practical barriers (time, spaces, practitioner capacities) and reportedly negative treatment expectations of many clinicians. Previous studies on fear extinction and vicarious exposure suggest vicarious learning as a mechanism for treatment of anxiety. One central mechanism of exposure is fear extinction. Interestingly, fear extinction can be induced by the mere observation of videos of non-fearful individuals reacting placidly to a feared stimulus. The extent to which vicarious fear extinction is transferrable to an exposure context remains elusive. Previous studies on vicarious exposure yielded promising results, including a study on long-term effects. After a comparison of videochat based vicarious exposure therapy (VicET) with in-vivo exposure (IVET), the investigators will examine fear and disgust reactions. Further, the investigators will examine fear and disgust generalization. To the best of our knowledge, no study has considered generalization and disgust extinction in a comparison of in-vivo exposure (IVET) with vicarious exposure therapy (VicET) in a controlled laboratory setting. Furthermore, our study proposes a new approach of implementing vicarious exposure therapy as participants observe a spider phobia treatment via videochat. VicET yields potential to surpass aversive components of IVET which may have caused IVET to be more stress-inducing to patients and less acceptable to clinicians. Further, videochat based VicET might be expandable to treatment groups and patients held back by physical barriers, posing a potentially cost-effective treatment for e.g. waitlist patients.

The investigators hypothesize that both treatment groups (IVET & VicET) will perform better than the waiting list control (WLC) group (indicated by stronger reductions in spider fear & avoidance measures, namely increased BAT steps, reduction in heart rate & SUDS fear ratings). The investigators further expect that IVET & VicET will exhibit similar treatment gains (reduction in subjective fear, increase in behavioral approach and decreased heart rate in the BAT), leading to no significant differences in spider fear & avoidance measures. It is predicted that generalization is effective in both the IVET and the VicET group (indicated by a reduction of fear & avoidance measures from Pre-Generalization-BAT to Post-Generalization-BAT). Therefore, the investigators expect the WLC group to exhibit smaller symptom improvements in all BAT measures to the nontreated spider. Given the absence of previous studies examining disgust generalization, no specific hypotheses can be drawn. The investigators expect no differences in measures of spider fear between IVET & VicET at follow-up, with the WLC group exhibiting higher levels of spider fear.

Further analyses will be conducted to investigate possible differences in IVET & VicET regarding subjective fear during treatment (on a behavioral, subjective and psychophysiological level), disgust, self efficacy & generalization. Questionnaires used in these analyses are listed as other outcome measures. An unexpected memory test will be inserted at post assessment to allow for investigation of memory for treatment experiences made during exposure therapy.

Inclusion Criteria:

• Presence of fear of spiders (Potential diagnosis of arachnophobia)

Exclusion Criteria:

• Reaching level 10 or higher in initial BATs
• Any acute or chronic mental disease more debilitating than fear of spiders
• Any debilitating acute or chronic somatic disease that prevents or counteracts exposure treatment effects (such as cardiovascular diseases)
• Heart Diseases (Pace makers, Bradycardia, Arterial Hypertonia, Heart Arrhythmia)
• Psychological, psychiatric, neurological or pharmacological treatment
• Drug or alcohol abuse
• Pregnancy
• Insect Sting Allergy