Tactons are tactile cues, which work in conjunction with a vibrotactile device that is placed on the body, and mechanically produces sensations on the skin surface; this allows the sense of touch to be used in Human-Computer Interaction (HCI). Effective tacton parameters of stimuli have been identified for a young population. However, studies have shown that the detection of vibrations degrades as a natural part of the aging process. Furthermore, there are a variety of different vibrotactile devices, and studies have shown that vibrotactile device type can affect detection thresholds. This presents a challenge since detection thresholds and recognition rates of different tacton cues, using one device, may not correlate to those of another. There is limited research on the effectiveness of tacton parameters and detection thresholds of simple waveforms in an older population of computer users, when using the C2 Tactor from EAI systems. This work used the C2 Tactor and stimulus parameters similar to those which have been shown to be effective in a young population, and conducted a comparison study between a young population of computer users between 18 and 25 years old and an older population of computer users between 55 and 75 years old. The study compared both groups' detection thresholds of three different simple waveforms (sinusoidal, square, and sawtooth) and found a significant increase in detection threshold by the older group. In addition a comparison of both groups' recognition rates of modulated sinusoidal waveforms was conducted and it was found that the older group had a significant decrease in recognition rates of modulated sinusoidal waveforms. In addition, it was shown that increasing the amplitude significantly improved the recognition rate of the older test group. A significant amount of variance in detection threshold and tacton recognition rates was found in the older test group, particularly those over the age of 60. The results of this study clearly showed a correlation between age, detection threshold, and recognition rates of tactons. The study shows that detection threshold and recognition rate deficiencies of older adults are functions of frequency and amplitude and not waveform or device.

Improvements in autonomous systems technology and a growing demand within military operations are spurring a revolution in Human-Robot Interaction (HRI). These mixed-initiative human-robot teams are enabled by Multi-Modal Communication (MMC), which supports redundancy and levels of communication that are more robust than single mode interaction. (Bischoff & Graefe, 2002; Partan & Marler, 1999). Tactile communication via vibrotactile displays is an emerging technology, potentially beneficial to advancing HRI. Incorporation of tactile displays within MMC requires developing messages equivalent in communication power to speech and visual signals used in the military. Toward that end, two experiments were performed to investigate the feasibility of a tactile language using a lexicon of standardized tactons (tactile icons) within a sentence structure for communication of messages for robot to human communication. Experiment one evaluated tactons from the literature with standardized parameters grouped into categories (directional, dynamic, and static) based on the nature and meaning of the patterns to inform design of a tactile syntax. Findings of this experiment revealed directional tactons showed better performance than non-directional tactons, therefore syntax for experiment two composed of a non-directional and a directional tacton was more likely to show performance better than chance. Experiment two tested the syntax structure of equally performing tactons identified from experiment one, revealing participants’ ability to interpret tactile sentences better than chance with or without the presence of an independent work imperative task. This finding advanced the state of the art in tactile displays from one to two word phrases facilitating inclusion of the tactile modality within MMC for HRI