# Attentional Bias Modification Training in Virtual Reality: Evaluation of User Experience
## 2 Materials and Methods
### Procedure  
This study was part of a project that received approval from the Research Ethics Committee of the University of Barcelona. All participants provided written informed consent before participating in the study. They were informed about data confidentiality and their right to leave the study at any time without any repercussions. Participants were informed that this study intended to examine body image disorders using virtual reality methods.  
To create the avatar, height and weight measurements were taken for each participant to calculate their body mass index. Additionally, two photos of the participant were captured--one from the front and another from the side--to accurately represent the participant's silhouette in the avatar.  
Before entering the VR environment, participants completed an attitude assessment toward technology using the MTUAS. They were then outfitted with VIVE Pro Eye(tm) HTC and body trackers and entered the VR setting. Following this, a five-minute visuo-motor and visuo-tactile stimulation aimed to create a strong sense of ownership of their virtual avatar. This process enhances the perception that the avatar reflects their real body [23], which heightens their presence in VR. After this phase, the participants' anxiety, fatigue, and comfort were measured for the first time (pre-session: PrS). Subsequently, the first series of ABMT commenced. We adapted the method from [PERSON] et al.'s study [11], wherein participants focused on geometric figures appearing over different parts of their body. In our study, these figures were evenly distributed across all body areas, aiming to diminish the attentional bias towards unpleasant body parts, observed in patients with anorexia nervosa and in individuals with high levels of body dissatisfaction. The ABMT involved four series of 75 trials each. Each trial displayed a geometric figure (triangle, square, or circle) in different colors (red, green, or yellow) on a body part. We ensured a balanced distribution of figures across body areas within each series and equally distributed them between the right and left sides of the body for lateralized body parts. Participants identified the shape of the figure in the odd series (first and third), while in the even series (second and fourth), they identified the color. This variation aimed to prevent boredom [11]. The software selected both the color and the shape for each figure randomly. During each trial, as participants paid attention to the figures, nearby body areas were gradually illuminated. Following four-second gaze fixation, a new figure would appear on a different body part. If a participant momentarily looked away, pausing their attention, the software waited for them to refocus on the figure before continuing to illuminate the corresponding nearby body area (refer to Figure 1). Each series took approximately 6 min to complete.  
Right after each series, their anxiety, fatigue, and comfort levels were evaluated using the visual analog scales, resulting in a total of five measurements during the intervention: baseline (PrS), and after series 1, 2, 3, and 4 (S1, S2, S3, and S4). Participants were given a 2-min break and seated in a chair after the VAS measurements, before starting the subsequent ABMT series. After completing all series and VAS assessments, the body trackers  
Figure 1: Example of ABMT trials, with the three possible figures and colors: (**a**) Yellow triangle on the right leg; (**b**) Green triangle on the left shoulder; (**c**) Red square on the chest; (**d**) Close-up of the body after the red circle on the stomach disappears and the surrounding body areas are illuminated.  
and HMD were removed, and participants were administered the SUS questionnaire to evaluate their user experience. Additionally, participants were given necessary rest time while the researcher explained the study's true purpose and addressed any queries.