The following is an excerpt from the final report of a National Eye Institute research grant, which investigated the use of the VideoTact as a tactile interface to Microsoft Windows.

Health and Human Services grant: SBIR 5-R44-EY08166-04
Development period: 4/19/94-6/30/96
Grant Title: "Haptic Display of Computer Graphics for the Blind"

All of the following primary goals of the project have been met:

• Development of a durable high density array, and lightweight, portable, low power drive electronics.
• Effectively interfacing to the Windows system, and translating the cursor and windowing events into appropriate electrotactile stimuli.
• Enabling blind test subjects to efficiently navigate the Windows environment.
• Effective methods of:
• Avoiding stimulus accommodation (the tendency of the skin to grow used to a static display).
• Avoiding masking effects by presenting qualitatively distinct stimuli ("tactile colors").
• Compensating for area/intensity summation (the perceived increase in stimulus magnitude as the number of active tactors increases).
• Gray scaling the stimulus so that the perceptual quality attributes do not change with the change in perceived intensity.
• Efficiently processing and displaying bitmap graphics (as well as dynamic video information from a video camera - for future use as a mobility aid).

• Generally, a tactor pixel position is determined by ratiometrically mapping its screen position (based on zoom level) to the array, but child windows (buttons and other controls) dominate parent windows in overlap conditions, or in cases of coincident mapping.
• Due to the possibility of multiple windows and/or window types being mapped to the same tactor, especially in the outermost zoom level, the cursor dimensions and tactile color dynamically change depending on the type of Windows object the cursor overlies; this helps to indicate what the underlying object is, as well as providing a form of "kinesthetic" feedback for mouse or digitizer motion. A beep is generated when the cursor type changes; this draws the user's attention to the corresponding tactile event.

• Appropriately displaying Windows events so that they are most discriminable; while we have achieved this to a large extent, it is clear that this area can be improved.
• Determining a greater number of "tactile color" regions in the stimulus space. Four such primary regions, each mutually distinct and gray scaleable, have been discovered so far, but we believe that this number could be greatly expanded. The tactile colors are used to help avoid masking effects when presenting one tactile object in the context of another.
• Reduction in the cost and complexity of the system. With the knowledge of the required stimulus range that we have gained from the Phase II research, we believe that with further development the system could be dramatically simplified and made affordable.

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