VR Calm Plus: Coupling a Squeezable Tangible Interaction with Immersive VR for Stress Regulation

TL;DR

This study addresses stress regulation through VR by introducing VR Calm Plus, a system that couples a squeezable, sensor-embedded plush with immersive VR scenes. Using a counterbalanced crossover design with 40 participants, it integrates PANAS-X, a custom subjective questionnaire, and physiological measures (HR, GSR, PRV) to compare squeeze-based interaction against a visual-only baseline. Findings show that squeeze interaction elevates positive affect, enhances perceived relaxation and control, and yields an 'active relaxation' physiological profile (greater HR reduction with preserved PRV and sustained GSR engagement). The work demonstrates the tangible benefits of embodied, multisensory VR for emotional well-being and provides design insights toward adaptive, bi-directional affective VR tools for stress management.

Abstract

While Virtual Reality (VR) is increasingly employed for stress management, most applications rely heavily on audio-visual stimuli and overlook the therapeutic potential of squeezing engagement. To address this gap, we introduce VR Calm Plus, a multimodal system that integrates a pressure-sensitive plush toy into an interactive VR environment. This interface allows users to dynamically modulate the virtual atmosphere through physical squeezing actions, fostering a deeper sense of embodied relaxation. We evaluated the system with 40 participants using PANAS-X surveys, subjective questionnaires, physiological measures (heart rate, skin conductance, pulse rate variability), and semi-structured interviews. Results demonstrate that, compared to a visual-only baseline, squeeze-based interaction significantly enhances positive affect and perceived relaxation. Physiological data further revealed a state of "active relaxation", characterized by greater reductions in heart rate and preserved autonomic flexibility (PRV), alongside sustained emotional engagement (GSR). Our findings highlight the value of coupling tangible input with immersive environments to support emotional well-being and offer design insights for future VR-based mental health tools.

Figures (6)

• Figure 1: Overview of the three stages in VR Calm Plus: (a) Adaptation and Shaping, showing vibrant particle-based orbs against a star-filled background; (b) Interaction and Guidance, presenting an expansive green field and a glowing white orb that guides attention through foreground, mid-ground, and background; (c) Meditation and Relaxation, depicting a dynamic white circle and a transition from clear sky to starry horizon that evokes calm and reflection. Together, these stages illustrate the progressive shift from energetic visualizations toward tranquil, immersive atmospheres.
• Figure 2: Overview of the Experimental Process and Research Design. The process flows from top to bottom, and the content in Step 4 is identical to that in Step 3, with the only distinction being between Squeeze Interaction and Audio-Visual experiences, i.e., Procedure A (Squeeze Interaction→Audio-Visual): participants experienced the Squeeze Interaction‐enabled VR system first, then the Audio-Visual version, and Procedure B (Audio-Visual→Squeeze Interaction): participants experienced the Audio-Visual version first, then the Squeeze Interaction version.
• Figure 3: Hierarchical overview of emotional responses across experimental conditions (PANAS-X). This visualization displays the mean emotional scores, stratified by three levels of granularity: Category (left, e.g., Basic Positive), Subcategory (middle, e.g., Serenity), and Fine-grained Emotion (right, e.g., Relaxed). The data is compared across three conditions: PreTest (lightest shade), Audio-Visual (medium shade), and Squeeze Interaction (darkest shade). The conditions are distinguished by varying contrast within the same hue family for each category (Middle/Green for Positive, Upper part/Red for Negative, Bottom part/Orange for Other Affective), providing high contrast for accessibility. The Squeeze Interaction's condition generally elicited higher positive emotional responses, particularly in dimensions of Serenity and Attentiveness, while maintaining low negative affect comparable to baseline. Error bars represent standard deviations.
• Figure 4: Emotion Score Differences between Squeeze Interaction and Audio-Visual. The bar plot illustrates the average difference in emotional scores between the Squeeze Interaction and Audio-Visual conditions across all measured emotion dimensions. A positive bar indicates a higher emotional response under the Squeeze Interaction condition, whereas a negative bar implies a stronger response under the Audio-Visual condition. Asterisks (*) indicate statistically significant differences (paired t-test, p $<$ 0.05).
• Figure 5: Overall Average Scores and Standard Deviation of Subjective Questionnaire. The Y-axis represents the score, and the X-axis denotes the abbreviated question, with the text in parentheses referring to a specific scenario.