WHAT MAKES AN AUTOMATED TELLER MACHINE USABLE BY BLIND USERS

Fifteen blind and sighted subjects, who featured as a control group fo r acceptance, were asked for their requirements for automated teller m achines (ATMs). Both groups also tested the usability of a partially o perational ATM mock-up. This machine was based on an existing cash dis penser, providing natural speech output, different function menus and different key arrangements. Performance and subjective evaluation data of blind and sighted subjects were collected. All blind subjects were able to operate the ATM successfully. The implemented speech output w as the main usability factor for them. The different interface designs did not significantly affect performance and subjective evaluation. N evertheless, design recommendations can be derived from the requiremen t assessment. The sighted subjects were rather open for design modific ations, especially the implementation of speech output. However, there was also a mismatch of the requirements of the two subject groups, ma inly concerning the key arrangement.