The purposes of the current research project are as follows:

1. investigate if the PMRT associated with a personalized-relaxing scenario in VR can facilitate the recalling of the relaxing image in the real world than the standard procedure (consisting of PMRT associated with the in-imagination exposure to a comfortable subjective context). The investigators assume that VR would be more efficient than in-imagination since it would make easy the visualization process favor people cope with more realistic sensory experiences than in-imagination exposure. Accordingly, the VR exposure would elicit the strongest association between the relaxation procedure (neutral stimulus, NS) and the relaxing context in VR (conditioning stimulus, CS);
2. whether exposure to a personalized VREs has a more significant impact on anxiety, depression, stress, sense of presence, and quality of psychological well-being; these constructs are investigated by comparing the participants' performance on self-report questionnaires (described in the next section), before the start of the training (T0; baseline), at the end of all the four relaxing sessions, one week after the end of relaxation sessions (T1; day 7), and during follow up (T2; day 14);
3. if the relaxing sessions administered via Zoom are more proper for managing anxiety and stress than a procedure learned via an audio registration.

Considering the ability to generate vivid visual images is positively associated with the capacity to feel present in a virtual world, all the participants are asked to fulfill two questionnaires before the VR or the Guided Imagery exposure to investigate the vividness and the capacity to control mental images respectively, and to control the impact of these two dependent variables on the sense of presence self-reported after the in imagination or VR exposure.

Each participant is randomly assigned to one of the three following different conditions:

1. Progressive Muscle Relaxation training via Zoom and Guided Imagery exposure A standardized protocol regarding the information on the training background is shared with participants.

   Then, they are invited to participate in four individually PMRT sessions (two sessions per week) deployed via Zoom.

   The fifth session (T1; day 7) is administered in-presence at the Virtual Reality Laboratory (A10-A11) - University of Padova; here, an in-imagination relaxing scenario is built up with the support of the Psychotherapist; then, participants are exposed to an in-vivo-PMRT-relaxing session conducted by the Psychotherapist, with the request to think about the in-imagination relaxing scenario, created before, during the progressive relaxation procedure.

   In the follow-up phase (T2, day 14), the therapist asks to recover the in-imagination relaxing scenario and relax, giving participants the same time allowed for the last guided relaxing session.

2. Progressive Muscle Relaxation training via Zoom and personalized VR exposure PMRT sessions and expected time length are the same as for the first group. Differences regard the fifth session, where the relaxing scenario is built with the psychotherapist support based on the VR's tools. Indeed, during the in-presence session, participants are exposed to a merged personalized and natural VR scenario and PMRT session administered by the Oculus Quest 2 tool.

   During the follow-up (T2; day 14), it is asked to recover the image and relax, making it available at the same time allowed for the last guided session.

3. Progressive Muscle Relaxation training based on audio-recording and personalized VR exposure In this condition, a standardized protocol of information and the four PMRT sessions are administered individually based on an audio track through the Moodle e-learning platform of the University of Padova.

During the fifth session (T1; day 7), users are asked to participate in an in-presence session in which they are exposed to a merged personalized, relaxing VR scenario and a PMRT session administered based on the Oculus Quest 2 tool. The last follow-up session has the same features as the other groups.

Assessment phases and Experimental procedure

T0 (baseline; before the PMRT sessions): 37 minutes.

The T0 assessment is the same for all participants and is administered at the Virtual Reality Laboratory (A10-A11)- Department of General Psychology, University of Padua. It implies the administration of the following measures:

• a demographic schedule (addressing age, gender, nationality, mother-tongue, marital status, years of school attendance, employment status, psychological problems/disorders, drugs use, medical conditions, neuromuscular issues, previous injures, previous experiences in relaxation practice or anxiety management training, or with Oculus);
• a series of self-report questionnaires investigating depression, anxiety, stress, quality of life, and distress coping strategies [State Trait Anxiety Inventory-Y (STAI-Y), Depression Anxiety Stress Scales-21 (DASS-21), Psychological General Well-Being Index (PGWBI), Coping Orientation to the Problems Experienced-Nuova Versione Italiana (COPE-NVI));
• resting heart rate detection with MiBand 2.

Before and after the four relaxing sessions administered remotely: 20 minutes globally.

Before and after each relaxation session, the personal level of tension is assessed using a 0 (no tension) to 10 (extreme tension level) scale; moreover, the state-anxiety level is evaluated based on the STAI-Y1.

The four-relaxation sessions are administered 2-3 days apart from each other for all three groups. The assessment phase is administered online based on the Moodle e-learning platform (University of Padova).

T1 phase (day 7): approximately 60 minutes. Before and after each relaxation session, subjects of tension and anxiety are assessed using a 0 (no tension) to 10 (extreme tension level) scale, and the state-anxiety level is evaluated based on the STAI-Y1.

Then, participants have been exposed to a PMRT session merged with a VR or a Guided Imagery procedure.

Before the in-imagination or the VR experience, all the participants fill out the Vividness of Visual Imagery Questionnaire (VVIQ) and the Test of Visual Imagery Control (TVIC). After the PMRT session, users compile a series of self-report questionnaires investigating depression, anxiety, stress, and quality of life (STAI-Y, DASS-21, PGWBI), and the VR group only fills out the VRSQ to monitor VR-related side effects (e.g., sickness, and headache), and the ITC-Sense of Presence Inventory to assess the sense of presence at the end of T1 phase.

The MiBand 2 was used during the entire T1 phase administration to detect the resting heart rate activity.

This assessment phase is administered based on the Moodle e-learning platform.

T2 (follow up; day 14): approximately 45 minutes. Before and after each relaxation session, subjects of tension and anxiety are assessed using a 0 (no tension) to 10 (extreme tension level) scale, and the state-anxiety level is evaluated based on the STAI-Y1.

All the users were exposed to a self-guided imagery experience in which those who were part of the VR group were asked to recall the personalized VR scenario experienced during the T1 phase (day 7). Instead, the Guided Imagery group retrieved the image participants had used in association with the PMRT during the T1 phase (day 7).

After the session, participants compile a series of self-report questionnaires investigating depression, anxiety, stress, quality of life (STAI-Y, DASS-21, PGWBI), and an ad hoc version based on the ITC-Sense of Presence Inventory to assess the sense of presence experienced during the imagery experience.

This assessment phase is administered based on the Moodle e-learning platform.

The follow-up assessment procedure requires approximately 25 minutes and is based on:

-a series of self-report questionnaires investigating depression, anxiety, stress, and quality of life (STAI-Y, DASS-21, PGWBI).

The MiBand 2 was used during the entire T1 phase administration (day 7), to detect the resting heart rate activity.

In general, the risks identified are principally related to difficulties in the technical implementation; in this context, mitigations strategies are represented by the feasibility study conducted in 2021, which helped obtain information for improving the VR environments according to users' needs and preferences. Effective recruitment strategies are deployed in the Trentino and Veneto regions to cope with the possible risk of drop-out of participants.](streamdown:incomplete-link)

Inclusion Criteria:

• General population
• Italian speaker
• Adult (age=> 18)
• Must be able to use a PC
• Must be able to use a Smartphone

Exclusion Criteria:

• Mental disorder diagnosis
• Clinical diagnosis of a neurological disorder
• Clinical diagnosis of epilepsy
• Have cardiac pacemakers
• Have metallic devices in the head-neck area
• Clinical diagnosis of infectious disorders
• Clinical diagnosis of gastrointestinal disorders
• Open wounds at the face level
• Clinical diagnosis of motor or visual dysfunctions
• Neuromuscular pain prevent the use of Oculus Quest 2