As a project for an Engineering Psychology class, Arlin Ladue and I redesigned the menu page of the Apple iTouch to increase comfort, accuracy and speed of operation.

There is a fast growing wealth of research surrounding the increasingly ubiquitous touch screen. They’re found in everything from ATM’s and refrigerators to cell phones and cars. The hand held touch screen is of special importance because, with the advent of Wi-Fi and smart phones, we find ourselves doing a variety of tasks from tiny, mobile devices. Unfortunately, the smaller the devices get (and the easier it is to take them with us) the more difficult it is to interact with them.

Touch screens in particular need to provide accurate and easy operation, in part because often we receive no haptic (physical) feedback when we make a selection. We can only know we’ve made the correct input by the resultant action on the device. The sleek design of the Apple touch products looks great, but is not always the easiest to hold or the easiest to navigate, thanks to small buttons all clustered more or less in the palm of your hand. Your thumb just isn’t that dexterous.

The design above, with buttons appearing on a slight slant, was inspired by studies that we found that showed the following:

  • The optimal sweep of the thumb relative to the palm is 20 degrees
  • Some areas of a rectangular screen can facilitate faster response times as a result of their location and the reach of the thumb
  • Different screen locations have different error rates. Those in the far corners, or corners very close to the base of the thumb, are harder to select
  • Moreover, the “footprint” that the thumb makes on the screen varies shape according to location on the screen. This affects accuracy.

The icons in our design lie on a 15 degree slant. Those areas with higher rates of “misses” (worse accuracy), the top left and bottom right corners, are used to display general information like battery life and Wi-Fi signal. The four main navigation buttons, those usually found along the bottom of an iTouch are moved to the bottom left corner, where they benefit from a reduced response time and good accuracy. They are also not obscured by the thumb, as can happen with the bottom right corner of the screen.

Our design was entirely conceptual, but it would be easy enough to implement. In fact, a simple control panel button could configure the iTouch for Left- or Right- hand users.

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