Abstract
Instrumented usability analysis involves the use of sensors during a usability study which provide observations from which the evaluator can infer details of the context of use, specific activities, or disturbances. This is particularly useful for the evaluation of mobile and wearable devices which are currently difficult to test realistically without constraining users in unnatural ways. To illustrate the benefits of such an approach, a study of touch-screen selection of on-screen targets is presented whilst walking and sitting, using a PocketPC instrumented with an accelerometer. From the accelerometer data, the user’s gait behaviour is inferred, allowing linking performance to gait phase angle, showing there were phase regions with significantly lower error and variability. The chapter provides examples of how information acquired via sensors gives quantitatively measurable information about the detailed interactions taking place when mobile, allowing designers to test and revise design decisions, based on realistic user activity.
Key Terms in this Chapter
Synchronisation: An adjustment of rhythms of two or more oscillatory systems due to their weak interaction.
Hilbert Transform: For an oscillatory signal s(t), the Hilbert transform H(t) gives the instantaneous phase and amplitude of s(t).
Oscillatory Systems: A system exhibiting periodically repeating changes of state.
Accelerometer: A sensor for measuring accelerations. These accelerations can be due to both translation or rotation of the sensor. The acceleration signal can be used to measure the orientation of the sensor, but only when it is held static.
Phase Angle: The phase angle gives a measure of how far an oscillating system is currently through it’s oscillation, from 0 to 2PI.
Rhythmic Interaction: Interaction based upon repeated movements where both actions and the timing of the actions are important to the interpretation of the meaning.
Instrumented Usability Analysis: The use of sensors during a usability study which provide observations from which the evaluator can infer details of the context of use, or specific activities or disturbances.
Context Aware Computing: Computer systems that can sense some aspects of the context of interaction and potentially adapt themselves accordingly.