  Vibration is an efficient way of conveying information from a device to its
user, and it is increasingly used for wrist or finger-worn devices such as
smart rings. Unexpected vibrations or sounds from the environment may disrupt
the perception of such information. Although disruptive effects have been
systematically explored in vision and audition, they have been less examined in
the haptic domain. Here we briefly review the relevant literature from HCI and
psychology, distilling principles of when distraction is likely. We then
investigate these principles through four experiments, examining how the timing
and modality of relatively rare or unexpected stimuli (surprise distractors)
affects the detection and recognition of vibrotactile target patterns. At short
distractor-target delays (< 350 ms), both auditory and vibrotactile surprise
distractors impaired performance. At a longer delay (1050 ms), performance was
not affected overall, even being improved with repeated exposure to the
vibrotactile distractors. We discuss the importance of our findings in the
context of HCI and cognitive psychology, and we provide design guidelines for
mitigating the effects of distraction on haptic devices.
