[Paper Review] Finger Based Technique (FBT): An Innovative System for Improved Usability for the Blind Users' Dynamic Interaction with Mobile Touch Screen Devices

Mohammed Fakrudeen, Sufian Yousef+1 more|arXiv (Cornell University)|Jan 1, 2014

Tactile and Sensory Interactions9 references3 citations

TL;DR

This paper introduces the Finger Based Technique (FBT), a novel touch-based interaction system for blind users to improve dynamic interaction with flat touch screen devices. By mapping virtual keys to specific finger positions—using single or double digit finger placement—FBT enables faster and more accurate text entry than iPhone VoiceOver, with single digit FBT achieving 3.26 WPM, significantly outperforming existing methods.

ABSTRACT

This paper presents Finger Based Technique (FBT) prototypes, a novel interaction system for blind users, which is especially designed and developed for non-visual touch screen devices and their applications. The FBT prototypes were developed with virtual keys to be identified based on finger holding positions. Two different models namely the single digit FBT and double digit FBT were propounded. FBT technique were applied using two different phone dialer applications: a single digit virtual key for the single digit FBT model and a double digit virtual key with audio feedback enabling touch as input gesture for the later one. An evaluation with 7 blind participants showed that single digit FBT was significantly faster and more accurate than double digit FBT. In addition to that, single digit FBT was found to be much faster than iPhone VoiceOver entry speeds in performing similar tasks. Furthermore, our research also suggests 11 accessible regions for quick access or navigation in flat touch screen based smart phones for blind users. These accessible regions will serve as a usability design framework and facilitate the developers to place the widget for the blind user for dynamic interaction with the touch screen devices. As far as is known to the authors, this is a novel suggestion.

Motivation & Objective

• To design and evaluate a novel interaction technique for blind users to enhance dynamic interaction with flat touch screen mobile devices.
• To identify accessible regions on touch screens where blind users can quickly and reliably access virtual keys using finger positioning.
• To compare the performance of single-digit and double-digit FBT prototypes in terms of entry speed, accuracy, and user preference.
• To provide a usability framework for developers to strategically place widgets in accessible regions for improved accessibility.

Proposed method

• The Finger Based Technique (FBT) maps virtual keys to specific finger positions on the touch screen, using the index and middle fingers to identify input locations.
• Two prototypes were developed: single digit FBT (10 virtual keys per finger) and double digit FBT (5 virtual keys per finger with audio feedback).
• The system uses the physical finger holding position as a spatial reference, eliminating the need for visual layout understanding.
• Text entry is performed by pressing virtual keys corresponding to finger positions, with audio feedback in the double digit model.
• The system was implemented using standard phone dialer applications to ensure real-world applicability and cross-platform compatibility.
• An evaluation was conducted with 7 blind participants performing text entry tasks using both FBT models and comparing results to VoiceOver speeds.

Experimental results

Research questions

• RQ1 How does the performance of single digit FBT compare to double digit FBT in terms of text entry speed and accuracy?
• RQ2 Can FBT achieve faster text entry speeds than existing eyes-free methods like iPhone VoiceOver?
• RQ3 Which finger positions on a touch screen are most accessible and usable for blind users during dynamic interaction?
• RQ4 What are the preferred interaction models among blind users, and what factors influence their preference?
• RQ5 Which regions on a flat touch screen are most suitable for placing widgets to enable quick, reliable access for blind users?

Key findings

• Single digit FBT achieved a mean entry speed of 3.26 WPM, significantly faster than the 2.1 WPM reported for iPhone VoiceOver in prior studies.
• Double digit FBT had a mean entry speed of 1.93 WPM, which was slower than VoiceOver but still comparable to other non-visual entry methods.
• There was no statistically significant difference in error count between single and double digit FBT (p = 0.14), indicating comparable accuracy despite speed differences.
• Despite slower performance, 70% of participants preferred the double digit FBT due to perceived ease of locating keys and familiarity with sequential input.
• The study identified 11 accessible regions on flat touch screens—such as above and below the index finger, thumb, and between fingers—where widgets can be optimally placed for blind users.
• The FBT system demonstrated cross-platform compatibility, as all virtual keys were located at finger-holding positions, suggesting potential for broader device support.