PhD Forum on Mobile Experiences

As mobile touch screen devices become increasingly ubiquitous, they are also becoming more accessible to people with visual impairments. Both Apple and Google have developed screen readers that are pre-installed on their devices, but Apple’s iPhone seems to be the most popular touch screen phone among blind people. The downfall with an iPhone with VoiceOver is that it is very slow, as the user averages about 1.5 words per minute typing this way. Washington University CS Ph.D. candidate Shiri Azenkot developed Perkinput, a nonvisual text entry method that uses the 6-bit Braille character encoding.

Perkinput is aimed to enable blind people to use mainstream mobile devices as efficiently and effectively as sighted people. It is based on Perkins Brailer, a mechanical device that uses 3×2 keys to represent each alphabet character and allows users simultaneously press the keys to enter a character. Perkinput allows the user tapping out braille characters using one tap with two hands on a larger screen such as a tablet mobile screen or two taps per character on a mobile phone.


Figure 1 Perkins Brailler and Perkinput. Braille encoding for ‘r’ is the binary string “111010”.

Shiri had participants use VoiceOver, which is what is currently used with smart phones, as well as Perkinput to compare the typing speed. Her results showed that not only did participants immediately enter more words a minute using Perkinput initially, but after multiple trials saw more improvement. The error rate was also lower using Perkinput. Here is a live demo:


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