Multi-point STM: Exploring the effect of drawing speed and the number of focal points on perceived intensity, valence and arousal in ultrasonic mid-air haptics

Title of the Paper

Multi-point STM: Effects of Drawing Speed and Number of Focal Points on Users’ Responses using Ultrasonic Mid-Air Haptics

Paper Information

• Subject Area: User perception and emotional responses to ultrasonic mid-air haptics
• Keywords: Ultrasonic mid-air haptics, perception, emotion, multi-point STM, haptic feedback, drawing speed, number of focal points, haptic patterns, user study

Research Background and Problem Statement

1. Identified Problems or Challenges:

   • Current research on ultrasonic mid-air haptics (UMH) predominantly focuses on single-point tactile mode (STM) technology, with an emphasis on parameters like drawing speed and their effects on user tactile perception (e.g., intensity). However, there is a lack of studies investigating the effects of multi-point STM.
   • Existing research has not examined how different modulation parameters in multi-point STM (e.g., drawing speed and number of focal points) impact overall user cognition and emotional responses, including perceived intensity, pleasantness, and arousal levels.

2. Significance:

   • UMH technology has broad application prospects, such as in virtual reality, advertising design, and therapeutic assistance. However, research has yet to fully reveal how multi-point STM affects users' tactile experiences and emotional perceptions.
   • Exploring the effects of new parameters (e.g., number of focal points) can help optimize haptic patterns and expand related application scenarios.

3. Research Motivation and Related Work:

   • Previous studies have extensively explored the effects of single-point STM on user perception, but how these findings can be extended to multi-point STM remains unknown.
   • To fill this research gap, this study aims to comprehensively analyze how the parameters of drawing speed and number of focal points affect users' tactile experiences (intensity) and emotional responses (pleasantness and arousal levels).

Solution

1. Method Overview:

   • The study proposes to investigate how the modulation parameters of drawing speed and number of focal points in multi-point STM individually or jointly influence user perception and emotional responses.
   • An experimental approach is employed, testing 9 combinations of conditions (3 drawing speeds and 3 numbers of focal points).

2. Innovations:

   • This is the first study to analyze the effects of the number of focal points (i.e., degrees of modulation freedom) on human perception and emotional responses.
   • It compares the similarities between multi-point STM and single-point STM to explore the transferability of parameter effects between the two.

3. Implementation Steps and Key Techniques:

   • Design experiments using the GS-PAT algorithm to generate multi-point STM.
   • Control variables (e.g., haptic shape, focal point size) to minimize confounding factors and ensure reproducibility.
   • Recruit 30 participants to evaluate their perceptions of intensity, pleasantness, and arousal levels.
   • Analyze normalized user ratings using statistical methods such as the Friedman test to assess the significant effects of independent variables on dependent variables.

Research Results

1. Specific Findings:

   • Effects of Drawing Speed on Perception and Emotion:
     • High drawing speed (5 m/s) enhances perceived intensity and arousal levels, but does not significantly affect pleasantness.
     • Low drawing speed (1 m/s) induces calmer and more pleasant emotional experiences.
   • Effects of Number of Focal Points:
     • Single-point STM produces the highest perceived intensity and arousal levels, while multi-point STM (especially 3 points) reduces perceived intensity and arousal levels but enhances pleasantness.
   • Combined Effects:
     • Single-point STM is suitable for enhancing perceived intensity and emotional arousal, while multi-point STM is better for reducing perceived intensity and fostering a sense of calmness, aiding relaxation.

2. Comparative Advantages:

   • Similar to traditional single-point STM, the effect of drawing speed on user responses in multi-point STM follows consistent trends, suggesting the potential for extending findings from single-point STM to multi-point STM.
   • The newly introduced parameter of the number of focal points has been shown to enable precise design of emotional experiences through point modulation.

3. Limitations and Future Directions:

   • The current study did not test the potential effects of other parameters (e.g., shape, sampling frequency) on user responses.
   • It is recommended to incorporate objective measurements (e.g., EEG signals or skin conductance responses) to deepen the understanding of emotional responses.
   • Future research should explore the potential of multi-point STM in complex haptic shapes and dynamic interactive simulations.

Conclusion and Design Implications

• The parameter modulation of multi-point STM provides designers with greater freedom to control users' tactile and emotional experiences:
  • Use single-point STM to design intense and stimulating haptic experiences.
  • Use multi-point STM to design calm and relaxing haptic experiences.
• The research findings can be applied to fields such as virtual reality gaming, advertising design, emotional expression tools, and therapeutic applications, enriching the diversity of user experience scenarios.