Jesse L. Eisert

Multimodal urgency coding: auditory, visual, and tactile parameters and their impact on perceived urgency

Through a series of investigations involving different levels of contextual fidelity we developed scales of perceived urgency for several dimensions of the auditory, visual, and tactile modalities. Psychophysical ratings of perceived urgency, annoyance, and acceptability as well as behavioral responses to signals in each modality were obtained and analyzed using Stevens Power Law to allow comparison across modalities. Obtained results and their implications for use as in-vehicle alerts and warnings are discussed.

Effect of Tactile Location, Pulse Duration, and Interpulse Interval on Perceived Urgency

Tactile displays hold promise as an effective and efficient means of presenting a wide range of information to the driver. This study examined the subjective perceptions of urgency and annoyance for tactile signals of different pulse duration, interpulse interval (IPI), and pulse pattern from devices called tactors located on the wrist, on the waist belt, or in the seat pan. Results revealed significant utility (steep increases in urgency without similarly steep increases in annoyance) for signals presented in pulse durations from 10 to 150 ms with decreasing utility beyond this range (200 ms or greater). Perceived urgency showed a decreasing trend as the IPI increased. Strikingly similar magnitude estimation functions were obtained across the three tactor locations. Results are discussed in terms of their implications for tactile display design in vehicles.

Designing Unambiguous Auditory Crash Warning Systems

A series of three studies examined the acoustic characteristics that contribute to a sound being unambiguously perceived as an urgent alarm within a vehicle context. In experiment 1, participants sorted a variety of sounds modeled after sounds currently in use in driver-vehicle interfaces (DVIs) into categories indicating highly critical warnings and alerts (or “alarms”), vehicle status sounds, or in vehicle social notifications. Results indicated that four criteria (peak-to-total time ratio, interburst interval, number of harmonics, and base frequency) explained 61% of the variance in categorization. From these criteria, cutoffs were determined and manipulated to create stimuli for an initial validation study. Experiment 2 results indicated that these criteria remained robust even when examined in a larger stimulus set and with different participants. Finally, Experiment 3 investigated rapid categorization under divided attention. Participants categorized alerts while driving in a desktop driving simulator and completing a secondary distracting task. Results indicate that previously defined parameter criteria and cutoffs are applicable in higher context and under load. Furthermore, sounds that met all criteria were responded to more quickly than those which met only some or no criteria, indicating that these criteria can be used to create sounds which are unambiguous and intuitive in an in-vehicle driving context.

Comprehension of vibrotactile route guidance cues

Two experiments with 24 participants each evaluated comprehension of vibrotactile route guidance instructions via a tactile seat in a driving simulator. Vibrotactile patterns were presented from an array of 8 tactors arranged in two rows of 4 tactors located in the seat pan. A faster pulse rate and a slower pulse rate as well as four distinct locations on the tactile seat (Front-Left, Front-Right, Back-Left, Back-Right) created 8 different combinations of stimuli. Across all participants, the most consistent interpretation was that the faster pulse rate played from the back two tactors was perceived as an instruction to make the next most immediate turn while a slow pulse rate from the front two tactors was interpreted as a cue directing the user to the direction of the next eventual turn. Results have direct implications for design of effective vibrotactile and multimodal route guidance systems.

Tactile Route Guidance Performance and Preference

We examined performance and preference for tactile route guidance formats. Participants drove a simulated vehicle through counterbalanced pairings of four distinct cities using one of four navigation systems (three tactile and one auditory control). One tactile system used only the pulse rate, the second system used only tactor location, and the third used both pulse rate and location to convey guidance instructions. All navigation systems provided both a preliminary and an immediate cue indicating to take the next most immediate turn. The pulse-rate route guidance system was the most commonly preferred system. Results also indicate that participants’ ability to accurately retrace their route and identify landmarks did not differ across navigation systems. All four systems resulted in equivalent wayfinding performance and support previous literature indicating that tactile guidance systems can effectively support navigation in unfamiliar environments.

Validation of Essential Acoustic Parameters for Highly Urgent In-Vehicle Collision Warnings

Objective The aim of this study was to validate the importance of key acoustic criteria for use as in-vehicle forward collision warning (FCW) systems. Background Despite recent advances in vehicle safety, automobile crashes remain one of the leading causes of death. As automation allows for more control of noncritical functions by the vehicle, the potential for disengagement and distraction from the driving task also increases. It is, therefore, as important as ever that in-vehicle safety-critical interfaces are intuitive and unambiguous, promoting effective collision avoidance responses upon first exposure even under divided-attention conditions. Method The current study used a driving simulator to assess the effectiveness of two warnings, one that met all essential acoustic parameters, one that met only some essential parameters, and a no-warning control in the context of a lead vehicle–following task in conjunction with a cognitive distractor task and collision event. Results Participants receiving an FCW comprising five essential acoustic components had improved collision avoidance responses relative to a no-warning condition and an FCW missing essential elements on their first exposure. Responses to a consistently good warning (GMU Prime) improved with subsequent exposures, whereas continued exposure to the less optimal FCW (GMU Sub-Prime) resulted in poorer performance even relative to receiving no warning at all. Conclusions This study provides support for previous warning design studies and for the validity of five key acoustic parameters essential for the design of effective in-vehicle FCWs. Application Results from this study have implications for the design of auditory FCWs and in-vehicle display design.

Vigilance and Fatigue A Double Sided Coin

Many everyday tasks, such as driving and reading technical reports, require sustained attention. These tasks may deplete attentional resources and/or lead to mind wandering, boredom and fatigue – cognitive states that result in impaired performance. Numerous competing theories exist to explain these performance decrements. In this panel, we will examine perspectives from both the fatigue and vigilance literatures, identifying points of common ground and differences in an attempt to further understand the underpinnings of performance decrements in tasks that require sustained attention. Experts in the interrelated yet frequently viewed as disparate areas of fatigue and vigilance are brought together to forge new theoretical ground.

Driving by the Seat of Your Pants A Vibrotactile Navigation Study

Vibrotactile navigation systems can provide drivers with directional information while reducing annoyance from a voice that interrupts on-going music and conversations. However, little is currently known regarding the working memory processes involved in utilizing vibrotactile navigation. Prior research has demonstrated that individuals differ in their sense of direction and ability to navigate and the working memory resources used to carry out the navigation task. Recent research has shown that vibrotactile cues can be used effectively to facilitate navigation while potentially reducing workload. The aim of this study is to examine impact of vibrotactile navigation systems on working memory. Specifically, the aim is to examine how they may differentially impact individuals based upon their sense of direction. It is predicted that the location based information provided by the vibrotactile navigation system may facilitate performance among individuals with a poor sense of direction – because it is not expected to rely on their verbal working memory. Conversely, vibrotactile systems are expected to hinder the performance of individuals with a good sense of direction since they may overload the visuospatial working memory processes. The results of this research will help in better understanding the differences between these individuals and help improve navigation system design to better navigational performance.

Optimal interface location and limits of gesture proficiency in an automobile

This paper explores the optimal location of gesture based in-vehicle technology for minimizing driver distraction, as well as the specific manipulative gestures that would accompany such gesture based in-vehicle technologies. Three different vehicle locations and ten different driver gestures were evaluated during testing. Participants in the study performed each of the gestures at all three locations, and results indicated that most individuals preferred using the steering wheel location. Participants’ responses indicated that they felt most comfortable with a repertoire of about seven gestures. Our initial findings suggest that a gesture-based interface system might be most effective when placed at the three o’clock position on the steering wheel, and when thee systems operate using a maximum of seven gestures.