Viral outbreaks can be experienced as disruptive and can be associated with traumarelated stress symptoms. In the current study, we adjusted the Dutch version of the Impact of Event Scale (IES) to assess traumatic stress symptoms related to the impact of the COVID-19 outbreak. The psychometric properties of this Impact of Event Scale with modifications for COVID-19 (IES-COVID19) were investigated by administering the IES-COVID19 to 380 university students who participated during the early stage of the COVID-19 outbreak, upon invitation via e-mail. Using confirmatory factor analysis, the factor structure of the IES-COVID19 was found to be similar to the original IES, indicating two latent factors: intrusion and avoidance, c 2 (85) = 147.51, CFI = .92, TLI = .90, RMSEA = .044, SRMR = .049. Cronbach's alpha showed acceptable internal consistency of the total IES-COVID19, a = .75. Pearson's correlations of the IES-COVID19 over time were also sufficient, demonstrating adequate test-retest reliability, r = .62. Significant correlations (ranging between .15 and .50) between the IES-COVID19 and symptoms of depression, anxiety, stress, stress-related rumination, as well as negative social interactions, demonstrate adequate convergent validity. Overall, the IES-COVID19 shows to be a valid and reliable measure that can be utilized to investigate traumarelated stress symptoms of intrusion and avoidance related to the short-and long-term impact of the COVID-19 outbreak.

A major objective of experimental psychopathology research is to improve clinical practice via the experimental study of treatment mechanisms. The success of this endeavor depends on the external validity of the procedures used to model the treatment component in the laboratory. We propose a general framework and a set of specific criteria that will allow evaluating whether a certain laboratory procedure is a valid model for a certain clinical treatment. We illustrate this framework by evaluating the validity of extinction as a laboratory model for clinical exposure therapy. Although we acknowledge the merits of the extinction model, we argue that its validity might not be as firmly established as the research community assumes. We also use extinction as an example to demonstrate how considerations of the proposed criteria can stimulate further improvements to existing models of treatment. We conclude that the systematic assessment of external validity of treatment models is an important step towards bridging the gap between science and practice in the field of experimental psychopathology.

Fear is an adaptive emotion that mobilizes defensive resources upon confrontation with danger. However, fear becomes maladaptive and can give rise to the development of clinical anxiety when it exceeds the degree of threat, generalizes broadly across stimuli and contexts, persists after the danger is gone or promotes excessive avoidance behaviour. Pavlovian fear conditioning has been the prime research instrument that has led to substantial progress in understanding the multi-faceted psychological and neurobiological mechanisms of fear in past decades. In this Perspective, we suggest that fruitful use of Pavlovian fear conditioning as a laboratory model of clinical anxiety requires moving beyond the study of fear acquisition to associated fear conditioning phenomena: fear extinction, generalization of conditioned fear and fearful avoidance. Understanding individual differences in each of these phenomena, not only in isolation but also in how they interact, will further strengthen the external validity of the fear conditioning model as a tool with which to study maladaptive fear as it manifests in clinical anxiety.

New technologies, such as virtual reality (VR) and augmented reality (AR), can be used as an add-on to exposure therapy for common anxiety disorders. Although the benefits of VR for exposure therapy have already been demonstrated extensively in research, AR applications are only just becoming widely available. Evidence for the added value and effectiveness of AR exposure therapy (ARET) is still scarce. The current study aimed to explore whether a first markerless AR iOS app for specific phobia could induce fear for multiple animal species in a general population sample. In two experiments, participants made use of the PHOBOS AR app in a behavioral approach task (BAT), using animals for which they were anxious, but not phobic. Self-report data and physiological measures were recorded. In Experiment 1, 108 participants chose one of the seven available animal species and were allocated to either a smartphone or tablet condition. Results showed increasing levels of self-reported anxiety with increasing levels of BAT difficulty. However, this increase was smaller in individuals reporting low levels of perceived realism. No effects on heart rate (HR) could be established. In Experiment 2, 52 participants were exposed to virtual spiders. For both self-reported anxiety and the interaction with perceived realism, results were similar to those of Experiment 1. Skin conductance did increase significantly from baseline to the highest level of difficulty of the BAT, and the severity of fear of spiders also appeared to be related to the fear response in the BAT. In conclusion, the study shows that animals presented in AR through a mobile device can evoke anxiety, which is a prerequisite for the implementation of ARET. However, further research should establish the effects of ARET in a clinical sample of people with specific phobias.

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