I recently came through this interesting design question, which has been stuck in my head since then.

Now, putting myself in such a persons shoes (though its weird and tough to think like that), without vision and hearing sense, i cant think of any substantial measure to do simple stuff, like how to decide where to push a coin to get a coke, or where to swipe my hand to book a ticket, or maybe something simple like that.

What i can think of is maybe, machine is designed in some touch-oriented fashion. Like we can get some knowledge of where to proceed, by touching at some random position.

I may sound too stupid, but that's it, nothing innovative is striking me right now.

I need a interview oriented answer. Any suggestions?

  • 1
    I don't see a question.
    – DA01
    Jun 20, 2013 at 21:11
  • The first idea is to make the machine easily detectable. Its vibration signature has to be unique, it seems. Jun 21, 2013 at 4:00
  • What is it exactly you need an answer to here? It looks like you're just starting a discussion about vending machine usage for deaf / blind people. You're asking for an 'interview oriented answer' but haven't stated what the question is.
    – JonW
    Jun 21, 2013 at 8:38

2 Answers 2


Your question seems to focus on placement of the keypad and how a designer would determine where to position these elements while relying solely on touch. If we can assume that a person who can neither see nor hear is walking unaccompanied, let's start with their accessing the machine. They're going to rely on touch to find the controls.

  • Place the controls at approach level for an average height person.
  • Make sure there are no sharp edges anywhere on the machine as it'll likely get patted down before the user finds the controls.
  • Consider using physical constraints that lead the hand in the direction you want it to go. A series of bumps that get smaller and closer together as the hand nears its destination could be one approach.
  • Consider providing a redundant set of controls at wheelchair level.

If we can assume the user is accompanied, we can also provide auditory or visual cues that might help the helper while still maintaining independence for the non-sighted, non-hearing user. It's an interesting design challenge, and one that could make vending machines easier to use for people with other physical challenges besides sensory deficit.


Many vending machines have braille printed near and/or on keypads that provides information about what they dispense and their transaction process. So single-step dispensing machines like soda/cigarettes machines would not pose a much usability problem for someone who is both blind and deaf, assuming the person is able to locate the machine.

Screen-based kiosks on the other hand would be more complicated, since many often involve substantial amount of information being displayed. The only way to universally convey the information would be through use of refreshable braille display.

Refresahable braille display is very effective way for a blind person to interpret and interact with information on computer screen without audio-basesd screen reader. Likely reason why we don't see one on kiosks is probably due to the fact that only 0.03% of US population is both deaf and blind, and most would receive assistance through other means.

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