Not all spacings are created equal: The Effect of Text Spacings in On-the-go Reading Using Optical See-Through Head-Mounted Displays

Title of the Paper

Not All Spacings are Created Equal: The Effect of Text Spacings in On-the-go Reading Using Optical See-Through Head-Mounted Displays

Paper Information

• Research Area: Human-Computer Interaction, Mobile Reading, Optical See-Through Head-Mounted Displays (OHMD)
• Keywords: Optical See-Through Head-Mounted Displays (OHMD), Mobile Reading, Text Spacing, Human-Computer Interaction, Multitasking, Smart Glasses, Reading Performance, Environmental Awareness

Research Background and Problem

• Problems and Challenges:

  • How to design information display styles for mobile reading using Optical See-Through Head-Mounted Displays (OHMD) to balance user reading performance and environmental awareness?
  • Is there an optimal range for text spacing design to enhance the reading experience?

• Significance:

  • OHMDs can support users in multitasking scenarios by delivering real-time information, but the data presentation methods need to minimize interference with primary tasks such as navigation and environmental awareness.
  • Default text spacing may not be suitable for the unique context of mobile reading.

• Motivation and Related Work:

  • Previous studies have explored design elements such as color, layout, and font style for OHMD text display but have overlooked the adjustment of text spacing.
  • The issue of spacing adjustment for small text has been less explored, but for displaying longer text, it is necessary to study spacing optimization methods suitable for mobile reading scenarios.

Solution

• Method or Solution:

  • The authors propose optimizing the mobile reading experience on OHMDs by adjusting "letter spacing" and "line spacing."
  • A multi-phase experimental design was adopted to study the effects of text spacing, determine the optimal spacing range, and compare it with existing text display strategies.

• Innovations:

  • Differentiating the impact of line spacing and letter spacing in mobile reading scenarios, the study found that line spacing significantly improves reading performance and navigation effectiveness compared to letter spacing.
  • Proposed an optimized text spacing strategy (100-pixel line spacing with no additional letter spacing) and validated its advantages.

• Implementation Steps and Techniques:

  • Study Design: Three experimental phases:
    1. Preliminary exploration of the impact of different text spacing ranges on OHMD mobile reading.
    2. Systematic study of the separate effects of letter spacing and line spacing on multitasking performance.
    3. Comparison of the optimized text spacing strategy with position strategies (center-bottom and mid-right screen placement).
  • Experimental Setup:
    • Participants were required to read text while completing indoor path navigation tasks, with path complexity categorized as simple and complex.
    • Experimental data were collected using NReal Light devices, controlling variables such as font type (Arial), font color (green), and background color (black transparent).
  • Data Collection Methods: Included reading performance (correct reading speed), navigation performance (walking speed and accuracy), task-switching performance (switching time and error rate), and subjective workload (NASA-TLX).

Research Findings

• Specific Findings:

  • Line spacing significantly enhanced reading speed, walking speed, and the accuracy and speed of task switching.
  • Increased letter spacing reduced reading speed but had no significant impact on walking speed or task-switching performance.
  • Compared to existing position strategies, the optimized line spacing strategy performed better in complex navigation scenarios.

• Advantages:

  • Compared to text layout strategies such as screen-centered or screen-side placement, the spacing adjustment strategy balanced user reading performance and environmental awareness.
  • By clarifying the differential impacts of letter spacing and line spacing, the study provides a better reading design for complex environments.

• Experimental and Evaluation Results:

  • Line spacings of 50 pixels and 100 pixels significantly improved reading and navigation performance, while increased letter spacing (especially 100 pixels) reduced reading speed.
  • In complex path navigation scenarios, text displays with optimized line spacing outperformed position strategies.

• Limitations and Future Directions:

  • Limitations:
    • The study only covered English text; applicability to other languages needs further verification.
    • Experimental scenarios were limited to indoor environments, excluding complex natural lighting conditions.
    • Lack of precise eye-tracking data support.
  • Future Directions:
    • Explore the applicability of text spacing strategies in multilingual and outdoor environments.
    • Develop intelligent adaptive text spacing adjustment systems.
    • Further investigate the impact of text spacing adjustments on graphical elements and other information representations.

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