Base on the insights of the unique VoiceOver usage pattern, we listed some principles of designing the mobile app interface for visually impaired users.
This is the common reading flow for sighted user we see in many apps.
Sighted user can skip irrelevant information at a glance, while VoiceOver user can not. The VoiceOver cursor moves along a certain path that causes visually impaired user has no choice but to go through everything on the screen.
So the best way to display information for visually impaired user is to conform with the VoiceOver reading flow, which should be straight and simple.
1. The area of each object on the screen should be big enough so it would easier for fingers to touch.
2. Do not stuff too many elements into a single block. And leave enought space between each block. This can prevent user from inadvertently trigger something unintended.
3. Every object should be attached to the edge of the screen in case the VoiceOver user who browse by dragging gesture miss any information.
4. Break a long-paragraph text content into smaller chunks can sharply enhance the browse efficiency for the visually impaired users. Instead of forceing them to wait for the intented messages showing up, let them decide wether to skip this piece of information or not while browsing.
Our interviewees also suggested that it’s better to place important buttons around the edge of the screen. Unlike feature phone, smartphone it doesn’t have any tactile feedbacks. So when you put the buttons around the edge, they can have a tangible reference to locate those virtual buttons.
Route A to B is the most complicated feature in BlindNavi. We’ve encountered with a lot of information display problems when designing the task flow. The search result of "transportation methods" contains a lot of informations at different levels of detail. So the question is, how to present all those information on the screen? After many rounds of interviews and comparison with other navigation apps, our final conclusion is to design around “time”. Provide the right information at the right timing and separate them to different screen.
On the 1st layer, user’s intention is to choose 1 among all those options. So the design should be able to help them quickly browse between options.
At this point, the only thing they need to know is what kind of transportation vehicles are involved & the total time cost of each option.
Once the decision has been made, users will be lead to the next layer. To this point, they would like to know more about their decision. So it’s a good timing to provide the itinerary outline & the step by step route details they’ll be going through on this screen.
And when they’re walking on the streets, they can turn on the the navigation mode. This is when, users don’t want spend so much time on the screen. They just want to follow the instruction n being guided.
So, BlindNavi will only show the instruction of user’s current location, which basically is the description of surroundings that helps to locate the user and identifies which direction to go.