It's Touching: Understanding Touch-Affect Association in Shape-Change with Kinematic Features

Title of the Paper

It’s Touching: Understanding Touch-Affect Association in Shape-Change with Kinematic Features

Paper Information

• Research Area: The emotional impact of dynamic shape changes on tactile perception in human-computer and sensory interaction
• Keywords: Tactile, shape-change, affective association, dynamic cognition, Bouba/Kiki, multisensory interaction, certainty, Circumplex Model

Research Background and Questions

Background

The potential applications of dynamic shape changes in affective computing are gaining increasing attention, particularly in therapeutic and social robotics contexts. However, there is limited research on the emotional responses elicited by dynamic shape changes through tactile perception, especially in the absence of visual information. This research is significant for practical scenarios involving non-visual interaction, such as designs for visually impaired users or environments without visual displays. Current studies often focus on the final state of shape changes, neglecting the emotional impact of the dynamic process itself.

Questions

1. What dynamic factors influence the association between tactile perception and emotions?
2. Do dynamic shape changes without visual information evoke consistent emotional associations?
3. How do temporal and force characteristics of dynamic shape changes affect users' emotional certainty?

Research Motivation and Related Work

• The authors build on the widely used "Bouba/Kiki" cross-modal interaction paradigm in psychology to explore the relationship between emotional responses and tactile perception during shape changes.
• Using the Circumplex Model and mouse movement trajectory analysis, the study investigates emotional certainty in dynamic shape changes.
• The authors hypothesize that the amplitude and frequency of dynamic shape changes may influence emotional responses and sensory interaction.

Solution

Methodology

The study involves two experiments:

1. Experiment 1: Examines the impact of shape size and convexity on the association between tactile perception and emotions.
2. Experiment 2: Investigates how the frequency of shape changes affects tactile emotional responses and user certainty.

Device Development

The authors designed a dynamic shape-changing device based on the Bouba-Kiki paradigm:

• Device Features: Equipped with inflatable flexible silicone material (Bouba represents smoothness, Kiki represents sharpness).
• Shape Transition Mechanism: Pneumatic control simulates smooth transitions between "Bouba" and "Kiki."

Experimental Design

1. The experiments isolated visual and auditory interference, allowing participants to perceive shape changes solely through tactile sensation.
2. The Circumplex Model was used to capture participants' emotional responses to shape changes.
3. Kinematic features of mouse trajectories (e.g., reversal counts and peak velocity) were analyzed to assess emotional certainty.

Innovations

1. Cross-modal Extension: Extends the Bouba-Kiki paradigm to the domain of dynamic shape changes.
2. Emotional Certainty Study: First to reveal tactile perception uncertainty during shape changes using dynamic mouse trajectory analysis.
3. Process Focus: Shifts attention to the dynamic process of shape changes rather than the final outcome.

Research Findings

Experiment 1 (Shape Size and Type)

• Specific Findings:
  • Large Bouba (smooth) shapes increased positive emotions (high valence) and reduced arousal levels (low stimulation).
  • Small Kiki (sharp) shapes increased negative emotions (low valence) and heightened arousal levels (high stimulation).
  • Dynamic shape changes elicited higher arousal levels compared to static shapes.
• Advantages:
  • Dynamic changes enhance users' emotional perception certainty.
  • The emotional impact of different shape sizes is consistent, particularly in terms of valence and arousal levels.
• Limitations and Future Directions:
  • Small-scale height variations in shapes may have potential impacts that require further exploration.
  • The role of visual connectivity differences needs deeper investigation.

Experiment 2 (Change Frequency)

• Specific Findings:
  • High-frequency changes: Increased users' arousal (alertness) levels.
  • Low-frequency changes: Reduced arousal levels and increased valence (but also induced greater uncertainty).
  • Frequency's role in emotional modulation: Lower frequencies elicited stronger positive emotional responses in Bouba-dominant shapes.
• Advantages:
  • Clarifies how frequency characteristics influence the depth of emotional perception.
  • Provides experimental evidence for designing shape changes, such as applications for "calmness" and "alertness."
• Limitations and Future Directions:
  • The generalizability of perceived frequency ranges and changes across different sizes needs validation.
  • Future studies could expand the experimental scope to other frequency ranges or more complex dynamic shapes.

Summary and Design Implications

Summary

• Influencing Factors:
  • Bouba/Kiki characteristics affect valence.
  • Dynamic changes and frequency features modulate arousal levels.
• Core Findings:
  • Dynamic shape changes elicit higher arousal levels compared to static shapes.
  • Low-frequency Bouba characteristics are suitable for evoking "calm" emotions, while high-frequency changes are more appropriate for alertness scenarios.
• Emotional Certainty:
  • Higher frequencies and more consistent shape changes increase user certainty.
  • Lower frequencies result in lower emotional certainty, potentially leading to perceptual confusion.

Design Implications

• Apply Kiki (sharp) characteristics in interaction scenarios requiring alertness or attention emphasis.
• Bouba (smooth) characteristics hold significant potential for meditation or stress-relief environments.
• The frequency of shape changes can be designed as a fine-tuning tool to enhance the range of users' emotional perceptions.
• Isolating the effects of visual and tactile sensory modalities in shape-change design can optimize non-visual user experiences.

Unresolved Issues and Future Directions

• How can multimodal combinations be expanded? Further exploration is needed into how shape, material, and texture of interactive devices affect tactile emotions.
• Can higher temporal resolution emotional recognition tools, such as dynamic emotional EEG integration, be incorporated into the design?