Design and evaluation of pactors for managing attention capture

In this paper, we present the design of a low-cost haptic actuator called a pactor that is capable of delivering tactile stimuli eliciting varying levels of attention capture. The pactor design consists of a crankshaft mechanism attached to an RC servo that produces a linear displacement at the endpoint. It can apply a 0-2.0cm displacement to the human body at a variety of actuation rates. We conducted a study to measure the displacement detection threshold for the pactors, and their perceived level of attention capture and urgency. In our study with 25 participants we found that actuation speed was the most significant factor affecting detection threshold. We also observed that the level of attention capture was dependent on both actuation speed and stimulus intensity. We propose that dynamic range of actuation speed and stimulus magnitude are important design parameters that enable actuators to achieve variable attention capture (VAC). This in turn will allow actuators to provide better opportunities to present information at an appropriate level of attentional salience.