Overview of Meta-analyses Investigating Vibrotactile versus Visual Display Options

Keep your finger on the pulse: Better rate perception and gap detection with vibrotactile compared to visual stimuli

Important characteristics of the environment can be represented in the temporal pattern of sensory stimulation. In two experiments, we compared accuracy of temporal processing by different modalities. Experiment 1 examined binary categorization of rate for visual (V) or vibrotactile (T) stimulus pulses presented at either 4 or 6 Hz. Inter-pulse intervals were either constant or variable, perturbed by random Gaussian variates. Subjects categorized the rate of T pulse sequences more accurately than V sequences. In V conditions only, subjects disproportionately tended to mis-categorize 4-Hz pulse rates, for all but the most variable sequences. In Experiment 2, we compared gap detection thresholds across modalities, using the same V and T pulses from Experiment 1, as well as with bimodal (VT) pulses. Visual gap detection thresholds were larger (3[Formula: see text]) than tactile thresholds. Additionally, performance with VT stimuli seemed to be nearly completely dominated by their T components. Together, these results suggest (i) that vibrotactile temporal acuity surpasses visual temporal acuity, and (ii) that vibrotactile stimulation has considerable, untapped potential to convey temporal information like that needed for eyes-free alerting signals.

Enhancing Physical Human Evasion of Moving Threats Using Tactile Cues

New human-centric approaches to safety can combine over-head camera views with situational awareness tools to enable humans to avoid rapidly evolving threats such as moving machines or falling debris. This article explores how 360° information can be used to inform humans of potential collisions. Specifically, we quantify how different individual (tactile, audio, and visual) and combined cue modalities affect failure rates and reaction times. Human-subject experiments were conducted in a custom virtual reality environment that simulates objects rapidly moving toward the subject. In order to successfully perform their task, the human subject must physically move their body out of the path of the moving threat before a collision occurs. This exploration of full body physical response differentiates this article from previous related studies. The results of the 18-subject study provide quantified data on a range of cues and cue combinations. The study quantified failure rates and reaction times as a function of index of difficulty (Fitt's Law) and threat directionality. The results confirm the hypothesis that the addition of tactile cues statistically improve performance compared to non-tactile cues with regards to failure rate and reaction time. This demonstrates how sensory cues can improve human physical response to rapid threats.

Supporting interruption management and multimodal interface design: three meta-analyses of task performance as a function of interrupting task modality

OBJECTIVE

The aim of this study was to integrate empirical data showing the effects of interrupting task modality on the performance of an ongoing visual-manual task and the interrupting task itself. The goal is to support interruption management and the design of multimodal interfaces.

BACKGROUND

Multimodal interfaces have been proposed as a promising means to support interruption management.To ensure the effectiveness of this approach, their design needs to be based on an analysis of empirical data concerning the effectiveness of individual and redundant channels of information presentation.

METHOD

Three meta-analyses were conducted to contrast performance on an ongoing visual task and interrupting tasks as a function of interrupting task modality (auditory vs. tactile, auditory vs. visual, and single modality vs. redundant auditory-visual). In total, 68 studies were included and six moderator variables were considered.

RESULTS

The main findings from the meta-analyses are that response times are faster for tactile interrupting tasks in case of low-urgency messages.Accuracy is higher with tactile interrupting tasks for low-complexity signals but higher with auditory interrupting tasks for high-complexity signals. Redundant auditory-visual combinations are preferable for communication tasks during high workload and with a small visual angle of separation.

CONCLUSION

The three meta-analyses contribute to the knowledge base in multimodal information processing and design. They highlight the importance of moderator variables in predicting the effects of interruption task modality on ongoing and interrupting task performance.

APPLICATIONS

The findings from this research will help inform the design of multimodal interfaces in data-rich, event-driven domains.

Field-Based Validation of a Tactile Navigation Device

In this paper, we present three field-based evaluations of a tactile land navigation system. In Experiment 1, we transition from a laboratory setting to rugged terrain used to train US Army soldier land navigation. Navigation in this challenging terrain requires careful attention to one's surroundings. Participants navigated 3 waypoints along 600 meters through heavily wooded terrain, using 1) map and compass, 2) standard alpha-numeric handheld GPS device, and 3) the tactile GPS system, while also responding to radio requests for information. Experiment 2 used the same challenging terrain during night operations, where participants must also search for live and silhouette targets, using 1) handheld GPS device, 2) head-mounted map-based GPS, and 3) the tactile GPS system. In addition to navigating, participants searched for silhouette and live (human) targets. Experiment 3 had participants navigate with 1) a commercial GPS arrow display, 2) the tactile GPS system, and 3) both together. We conclude that tactile navigation displays can be used in strenuous outdoor environments and can outperform visual displays under conditions of high cognitive and visual workload.